Are prebiotics good for dogs and cats? An animal gut health expert explains

By Kelly S. Swanson, PhD, The Kraft Heinz Company Endowed Professor in Human Nutrition, University of Illinois at Urbana-Champaign, USA

Pet dogs and cats are cherished companions. In developed countries, many households with pets treat them like family members. Similarly to humans, a high level of nutrition and veterinary care promotes health and longevity. As people become more aware of what they feed themselves and their human family, they make the same considerations for their canine and feline companions. Pet food trends have closely followed those of the human food industry over the last couple decades, with high-quality natural and organic foods gaining popularity.

One way pet food companies have enhanced their products is by incorporating functional ingredients into their formulas. Functional ingredients provide benefits beyond that of their nutrient content. One of the most popular target areas for functional ingredients is pet gastrointestinal health, with structure/function claims of “supporting digestive health”, or something similar, being quite common. Loose stools, constipation, and various gastrointestinal disorders and diseases such as inflammatory bowel diseases and irritable bowel syndrome are common in pets. The task of “poop scooping” after the dog in the park or cleaning out the cat’s litterbox provides owners with an opportunity for daily assessment of stool quality and serves as a reminder of how important diet is to gut health.

Benefits of prebiotics for pets

Many ingredients, including dietary fibers, prebiotics, probiotics, synbiotics, postbiotics, and other immunomodulators may provide gastrointestinal benefits to pets, but today we will focus on prebiotics. The most recent ISAPP expert consensus panel on prebiotics clarified that the prebiotic concept not only applies to humans, but also to companion and production animals (Gibson). Dogs and cats evolved as Carnivora, mainly consuming high-protein, high-fat diets that were low in fiber, and their short, simple gastrointestinal tracts have a limited capacity to ferment non-digestible substances. Nonetheless, they possess an active microbiota population, primarily in the colon, that may be manipulated by diet to impact health.

Most prebiotic research in pets has focused on the gastrointestinal tract. Prebiotic administration has been shown to reduce the incidence or severity of infections (Apanavicius; Gouveia), improve stool consistency (Kanakupt), and beneficially shift fecal microbiota and metabolite profiles (Propst). A few have reported the benefits that prebiotics may have on metabolic health, demonstrating improved glucose metabolism and insulin sensitivity in pets consuming prebiotics (Respondek; Verbrugghe). Since we’re looking at foods rather than at medicines that address disease, the majority of research has been conducted in healthy animals so evidence of health improvements in diseased pets is sparse.

Types of pet-friendly prebiotics

Although a few studies have tested galactooligosaccharides (GOS), mannanoligosaccharides, and other potential prebiotics, by far the most common prebiotics studied and present in pet foods are the non-digestible fructans. Natural sources, such as chicory, or isolates and extracts that have a high purity, including short-chain fructooligosaccharides (FOS), oligofructose, and inulin, are all present in pet foods.

Which pets benefit most?

Similar to dietary fiber, the need for prebiotic inclusion is dependent upon diet type and formulation. Animals consuming plant-based diets that are rich in natural fibers and non-digestible oligosaccharides likely do not require additional fermentable substrate in the formula. Dogs and cats fed high-protein, meat-based diets, however, typically have greater fecal odor, a higher colonic pH, and higher density of potential pathogens due to a high rate of protein fermentation. In those diets, prebiotic inclusion may help animals normalize their gut microbiota abundance and metabolism.

Prebiotics may be fed to all pets, but will likely provide the greatest benefits to geriatrics, animals who are or have received antibiotics, those under high stress conditions, or those with certain gastrointestinal disorders. The low caloric density of prebiotics and the metabolic benefits that come from their fermentation will be most beneficial to pets with obesity and diabetes. As for all functional ingredients, dosage is important. When comparing dogs and cats, dogs usually can tolerate a higher dosage than cats. In regard to dog size, small dogs can typically tolerate a higher dosage (per unit body weight) than large dogs, which are more susceptible to loose stools. In most commercial pet foods, prebiotic inclusion levels are <0.5% of the formula to limit side effects.

Further research on prebiotic substances

Using the powerful tools that are now available to study gut microbiota and host physiology, future research can hopefully determine what microbes are most important to the health of dogs and cats and identify mechanisms by which prebiotics provide health benefits to pets. Further testing, which may include plant-based ingredients, yeast-based products, and milk oligosaccharide mimics, will hopefully identify other prebiotic substances and continue to expand our knowledge in the field.

 

Kelly Swanson joined the ISAPP board of directors in June, 2020, providing valuable expertise in animal gut health and overall health. Swanson also chaired the 2019 ISAPP-led international consensus panel on the definition of synbiotics.

 

 

 

What makes a synbiotic? ISAPP provides a sneak peek at the forthcoming international scientific consensus definition

By Kristina Campbell, science and medical writer

The word ‘synbiotic’ is found on the labels of many different products, from supplements to chocolate bars, and it has generally been understood to be a combination of a probiotic and a prebiotic. But what happens when scientists want to test whether these combination products really deliver any health benefits? Can these products be tailored to have specific effects on the body or on the human gut microbiota? Agreeing on a clear definition of synbiotics is needed to provide focus for scientific research in this area, to facilitate the design of studies, and to allow for progress wherein their health effects are uncovered.

The scientific definition of synbiotic was the central topic of the international scientific panel brought together by ISAPP in May 2019 in Antwerp, Belgium. Members of the panel, eleven of the top academic experts in the field of probiotics and prebiotics, gathered to clarify a scientifically valid approach for use of the word ‘synbiotic’, and to communicate this by position paper. The outcome of this consensus panel is currently in press at Nature Reviews Gastroenterology & Hepatology.

Kelly Swanson, Professor in the Department of Animal Sciences and Division of Nutritional Sciences at University of Illinois at Urbana-Champaign, chaired the panel and led the paper’s publication. Swanson has been studying gastrointestinal health in both humans, companion animals (dogs and cats) and rodent models for the past 20 years—and having followed the rapid advances in the field of probiotics and prebiotics during those two decades, he knew the task of creating a synbiotic definition would not be easy.

He says, “The field is highly complicated, so an interdisciplinary panel was essential. The main areas of expertise included microbiology and microbial ecology; gastrointestinal physiology; immunology; food science; nutritional biochemistry and host metabolism.”

A timely discussion

According to Swanson, an increase in research interest, built on a foundation of recent scientific and technical gains, made this the right time to come to consensus on a synbiotic definition. He says, “Over the past decade, technological advances have allowed scientists to study the gut microbiome at a molecular level. In addition to characterizing the composition of the gut microbes, researchers are learning more about their biological activity and how they may impact host health.”

Furthermore, clarity about the definition was urgently needed because of the rapidly growing synbiotics market. Consumers seem to be more aware of synbiotics than ever, but they face a bewildering array of product offerings labeled as ‘synbiotic’ without a clear understanding of what that term entails and with no framework for establishing scientific efficacy. Swanson says, “As the field has moved forward and the sales of probiotics and prebiotics have increased, there has been more interest in combining substances to enhance efficacy. Some of these combinations may function as synbiotics, but it is not guaranteed. Rather than randomly combining substances together, there should be scientific rationale supporting their use.”

Clarifying the concept

One of the first questions the panel members had to tackle was whether to stick to the idea of a synbiotic as ‘probiotic plus prebiotic’, thus leaning heavily on the ISAPP-led international consensus definitions of probiotics and prebiotics published in 2014 and 2017, respectively. But the panel members decided this narrow scope would ultimately limit innovation in the synbiotic category.

Swanson explains, “While many synbiotics may be composed of an established prebiotic and established probiotic, the panel did not want to restrict scientific advances in the synbiotic category by requiring use of components already established on their own.”

As a result, he says, previously untested live microbes and potential prebiotic substances could be considered a synbiotic if the combination showed efficacy, and if the health benefit came from administering both the live microbe and the substrate it utilized—that is, the microbe together with its ‘food’.

Another conclusion from the panel is that probiotics (with known health benefits) and prebiotics (with known health benefits) cannot be called synbiotics unless they have been tested together. “There should be a rationale supporting the combination used, and then testing of the combination to confirm its efficacy,” says Swanson.

The panel suggests a synbiotic may be composed of either of the following, as long as efficacy is demonstrated for the combination:

  • Established probiotic + established prebiotic (each component meeting the efficacy and mechanistic criteria for each)
  • Previously untested live microbe + a substrate that is selectively utilized by the co-administered live microbe

Further details, including two different ‘categories’ of synbiotics, will be provided in the published paper.

In addition to the definition, the publication will cover the history of synbiotic-type products, how these products can be characterized, levels of evidence that currently exist versus levels of evidence desired, points about safety documentation and reporting, and relevant characteristics of the target hosts.

A remaining challenge—not just for the expert group, but also across the field—is the difficulty of establishing causal links between substances’ effects on the gut microbiota (e.g. ‘selective utilization’ of a substrate) and health outcomes.

While the publication of the synbiotic definition will be an important milestone, Swanson anticipates further discussion in the years ahead. “As more is learned, I expect the criteria for assessing synbiotic efficacy will continue to change,” he says.

An update on the scientific consensus definition of synbiotic was presented to ISAPP members at the 2020 virtual meeting in June.

 

ISAPP partners with British Nutrition Foundation for fermented foods webinar

Did you miss the live webinar? Access the archived version here.

From sourdough starter tips to kombucha flavor combinations – if you’ve checked a social media feed lately, you’ll know how many people are sharing an interest in fermented foods as they self-isolate during the pandemic. And with this rise in popularity comes a host of questions about the practice and the science of fermented foods.

To meet the need for science-based information about fermented foods, ISAPP has partnered with the British Nutrition Foundation (BNF) on a free webinar titled ‘Fermented Food – Separating Hype from Facts.’ The BNF is a UK-based registered charity that brings evidence-based information on food and nutrition to all sectors, from academia to medicine.

The webinar, designed for practicing dietitians and nutrition-savvy members of the public, featured three leading scientific experts who explained the microbiology of fermented foods, the evidence for their health effects, and who might benefit from making these foods a regular part of the diet. Viewers will come away with a clear understanding of what fermented foods are and what evidence exists for their health benefits.

The webinar was held live on Wednesday, July 1, 2020 from 1pm-2pm (BST).

Webinar speakers & topics

 Understanding fermented foods: Dr. Robert Hutkins, University of Nebraska, USA

Exploring the evidence for effects of fermented foods on gastrointestinal health – how strong is it? Dr. Eirini Dimidi, Kings College London

What role can fermented foods have in our diet? A public health perspective, Anne de la Hunty, British Nutrition Foundation

For a quick primer on fermented foods in advance of the webinar, see the short ISAPP video here or the ISAPP infographic here.

[IN SPANISH] Creciente interés en Argentina en microorganismos benéficos y alimentos fermentados

Dr. Prof. Gabriel Vinderola, Investigador Principal CONICET, Instituto de Lactología Industrial (INLAIN, CONICET-UNL), Profesor Asociado, Cátedra de Microbiología, Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santa Fe, Argentina.

El interés sobre las bacterias intestinales, los alimentos fermentados y los probióticos está en aumento en Argentina y la región. Nutricionistas e influencers, que en los últimos años han comenzado a promover un estilo de vida más saludable, están aprovechando sus redes sociales para publicar recetas sobre cómo hacer alimentos fermentados, consejos para promover una microbiota más saludable e información sobre el posible papel de los probióticos y prebióticos en la salud humana. Pero, ¿están estas recomendaciones basadas en la ciencia? No siempre! En particular, he tenido la oportunidad de contribuir a que la comunicación sobre la microbiota, los alimentos fermentados, los probióticos y los prebióticos se haga desde la ciencia, para una audiencia amplia y con un leguaje simple.

En Argentina, y desde hace 50 años, hay un programa de televisión con un formato particular: la anfitriona, la Sra. Mirtha Legrand, cada domingo invita a almorzar a 4-6 personas para hablar, durante 3 horas, de política, economía, cultura popular, arte e incluso ciencia. Según ella, se trata del programa de televisión que se ha transmitido, ininterrumpidamente, por más tiempo en el mundo. Cada domingo, miles de personas de Argentina, Uruguay y Paraguay lo sintonizan. En octubre de 2019, me invitaron a unirme a la mesa y hablar sobre el mundo invisible que existe dentro y alrededor de nosotros. Discutimos cómo podemos beneficiarnos de las bacterias a través de alimentos fermentados y los probióticos, y cómo alimentar nuestros microbios intestinales con prebióticos. De hecho, en 2019, di más de 40 charlas sobre este tema a audiencias muy variadas a través de conferencias para profesionales, cursos para estudiantes de doctorado, seminarios y talleres para gente sin formación científica. Estas acciones están dirigidas no sólo a científicos y estudiantes, sino también a niños en escuelas, adolescentes en clubes deportivos y gimnasios o personal que trabaja en hospitales. El interés por los “bichos amistosos” es amplio y variado, y se alimenta de la información que circula por programas de radio y televisión.

“Almorzando con Mirtha Legrand”, un talk show que ha estado al aire en televisión por más de 50 años en Argentina, donde la discusión sobre microorganismos benéficos fue llevada a la mesa por Gabriel Vinderola (último a la derecha). Mirtha Legrand, de 93 años, está en el centro de los invitados (03/10/2019).

El entusiasmo de la audiencia fue inmediato. Se recibieron numerosos mensajes por correo electrónico, WhatsApp, Facebook o Instagram. La gente demostró estar interesada en saber más, preguntando por fuentes confiables para leer material con base científica, pero “fácil de entender”, planteando preguntas específicas sobre cuestiones intestinales, de dónde obtener probióticos y prebióticos o cómo hacer alimentos fermentados de manera segura. Afortunadamente, las infografías de la ISAPP sobre probióticos y prebióticos ya estaban disponibles en español, traducidas por Miguel Gueimonde (España) y por mí, y fueron un recurso muy utilizado. Sin embargo, la gente solicitaba más información, y hacía más y más preguntas específicas.

Estimulado por el creciente interés, me puse en contacto con una chef local, Ana Milena Giacomini, quien dejó atrás su carrera profesional de abogada para abrir un pequeño restaurante con un menú basado principalmente en alimentos fermentados. Ella ofrece sabrosos platos que incluyen yogur casero, chucrut, kimchi, kéfir de agua, humus fermentado, pan de masa madre, panqueques hechos de harina de arroz fermentada, kombucha, kvass y bebidas gasificadas a base de jengibre fermentado. Con ella organizamos talleres de 4 horas de duración, que actualmente están suspendidos debido a la pandemia por COVID-19. En estos talleres Ana prepara en vivo algunos de estos alimentos fermentados, para a continuación degustarlos, mientras yo explico la ciencia y la microbiología que hay detrás de ellos. Se discuten aspectos relacionados con la identidad, seguridad, estabilidad y los posibles efectos sobre la salud de estos productos. Siempre enfatizo las diferencias entre los alimentos fermentados y los probióticos, a la vez que discuto el potencial valor de incorporar alimentos fermentados, probióticos y prebióticos a la alimentación diaria como una forma de promover la salud intestinal. En estos talleres proporciono además información más específica sobre los efectos en la salud de probióticos para los que se dispone de sólidos meta-análisis que apoyan el uso de ciertos microorganismos en la prevención de la diarrea asociada a antibióticos en niños, el tratamiento de cólicos infantiles, la prevención de alergias y la reducción de la inflamación intestinal. Otros talleres con diferentes chefs de diferentes lugares de Argentina están en lista de espera para cuando esta pandemia de coronavirus termine.

Cena de cuatro pasos que incluye alimentos fermentados en cada plato, preparada por el chef argentino Martin Russo. La entrada consistía en zanahorias fermentadas y hummus, servidas en pan de masa madre.

En estos talleres se espera la asistencia de 30-35 personas cada vez. Entre ellas, nutricionistas interesados en dar respuestas adecuadas a sus pacientes, que se enteran de estos temas en los medios de comunicación o en las redes sociales. Pero también asisten personas que quieren aprender cómo hacer alimentos fermentados, dónde encontrar probióticos y prebióticos, u obtener una orientación clara sobre cómo incorporar bacterias vivas a su dieta. También asisten otros profesionales de la salud (gastroenterólogos, pediatras), docentes e incluso gente de la industria.

El postre eran bochas de helado cubiertas por la madre del vinagre (círculo transparente en la parte superior), enjuagadas y endulzadas.

La mayoría de los interesados en asistir a estos talleres tienen poca experiencia en alimentos fermentados, sólo están familiarizados con productos como el yogur, el queso, el vino o la cerveza. Es más, muchos de ellos desconocen que estos alimentos son fermentados, o no poseen una idea clara de lo que es la fermentación. La mayoría de ellos también tienen un conocimiento muy limitado, o incluso información errónea, sobre los probióticos y prebióticos. Estos talleres ofrecen la posibilidad de que personas interesadas en estos temas aprendan y prueben nuevos alimentos, de que conozcan la ciencia que hay detrás de los alimentos fermentados, los probióticos y los prebióticos, y de que aprendan las diferencias entre ellos de forma científica y en un “lenguaje fácil de seguir”. Estos encuentros son una forma de expandir el interés del público en general sobre el mundo invisible que habita dentro y alrededor nuestro.

Growing interest in beneficial microbes and fermented foods in Argentina

By Prof. Gabriel Vinderola PhD, Associate Professor of Microbiology at the Faculty of Chemical Engineering from the National University of Litoral and Principal Researcher from CONICET at Dairy Products Institute (CONICET-UNL), Santa Fe, Argentina

Awareness of gut microbes, fermented foods and probiotics has been on the rise in Argentina. Nutritionists and influencers, who in recent years have begun promoting a healthier lifestyle, are leveraging their social networks to post how-to instructions for making fermented foods, advice to promote a ‘healthier’ microbiota, and information on the potential role of probiotics and prebiotics in human health. But are these news items and recommendations based on science? Not always! I’ve been fortunate to have had the opportunity to make sure the science is correctly communicated to a broad audience on the microbiome, fermented foods, probiotics and prebiotics.

In Argentina, for the last 50 years, there has been on the air a TV show with a particular format: the hostess, Miss Mirtha Legrand, invites 4-6 people to have lunch every Sunday, talking about politics, economy, popular culture, arts and even science for 3 hours. According to her, this is the longest continuously running TV program in the world. Every Sunday several thousands of people from Argentina, Uruguay and Paraguay tune in. In October 2019, I was invited to join the table and to comment about the invisible world inside and around us. We discussed how we can profit from bacteria through fermented foods and probiotics, and how to feed our gut microbes with prebiotics. In fact, in 2019, I gave more than 40 talks on this topic to scientific audiences at conferences, as courses for Ph.D. students, as seminars and as workshops. These efforts are targeted not only to local scientists and students, but also to children in schools, local sport clubs in small towns, gyms and hospitals. The interest in friendly bugs is wide-ranging and varied, and fueled by information from radio and TV programs.

“Having lunch with Mirtha Legrand”, a talk show on television for more than 50 years in Argentina, where the discussion on beneficial microbes was brought to the table by Prof. Gabriel Vinderola (far right). Mirtha Legrand, now 93 years old, is in the center (October 3rd, 2019).

The enthusiasm of the audience was immediately evident. Lots of messages came by email, WhatsApp, Facebook or Instagram. People were anxious to know more, inquiring about trustworthy sources to read scientific-based but “easy-to-understand” material, posing specific questions about their gut feelings, where to get these probiotics and prebiotics or how to make fermented foods in a safe manner. Fortunately, the ISAPP infographics on probiotics and prebiotics were already available in Spanish, translated by Miguel Gueimonde (Spain) and me, and these were a welcome resource. Yet people still wanted more information, and asked more and more specific questions.

Spurred by such widespread interest, I contacted a local lawyer-turned-chef, Ana Milena Giacomini, who left behind her professional law career to open a small restaurant with a menu heavily based on fermented foods. She features such delights as home-made yoghurt, chucrut, kimchi, sugary kefir, fermented hummus, sourdough bread, pancakes made out of fermented rice flour, kombucha, kvass and a gasified drink from fermented ginger. With her, we organized 4-hour workshops, which are currently on hold due to COVID-19. These workshops feature Ana preparing some of these fermented foods live, followed by tasting, while I explain the science and microbiology behind them. I share factors related to the identity, safety, stability, and potential health effects of these products. I emphasize the differences between fermented foods and probiotics, while discussing the potential value of incorporating fermented foods, probiotics and prebiotics to the daily diet as a way to promote gut health. I provide more specific information on health effects for which robust meta-analyses are available to support the microbes’ use, such as prevention of antibiotic-associated diarrhea in children, treatment of infant colic, prevention of allergies, and downregulation of intestinal inflammation. Other workshops with different chefs from different locations in Argentina are in line for when the coronavirus pandemic ends.

Part of the four-course dinner containing fermented foods prepared by chef Martin Russo. The starter consisted of fermented carrots and hummus, served on sourdough bread (pictured).

These workshops are expected to be attended by 30-35 people each time. Nutritionists are interested in giving sound responses to their clients, who hear about these topics in the media or in social networks. But also, people come who want to learn how to make fermented foods, where to find probiotics and prebiotics, or to gain clear guidance on how to incorporate live bacteria to their diets. Other health professionals (gastroenterologists, pediatricians), educators and even people from the industry also attend.

 

The dessert was ice cream balls covered by the mother of vinegar (transparent circle on the top), rinsed and sweetened.

Most people interested in attending these workshops have narrow experience with fermented foods, only being familiar with such things as yoghurt, cheese, wine or beer. Some of them do not know that these foods are indeed fermented, or do not have a clear idea what fermentation is about. Most of them also have a very limited awareness, or even misinformation, about probiotics and prebiotics. These workshops offer the possibility for the curious to learn and to taste new foods, to get insights on the science behind fermented foods, probiotics and prebiotics, and to learn the differences between them in a science-based manner in an “easy-to-follow language”. These encounters are a great way to expand the interest by the general public on the invisible world inside and around us.

The Horses: Daily Routines in the COVID-19 Era

By Gregor Reid BSc (Hons), PhD, MBA, ARM CCM, Dr HS, FCAHS, FRSC

It’s dawn and as per every day, I put on my mask. It’s not the type of mask you might think in these anxious times. It’s to prepare hay bags for our two horses. Hay, filled with the dust and mold particles that frankly my lungs despise.

After preparing the hay, I then begin my walk. Our faithful dog by my side in between racing after a ball that ejects from a plastic thrower in my right hand. All around, the sounds of birds starting their day in song, zooming in to find a spot on a feeder filled with sunflower seeds and nuts. The air is cool, but it opens my lungs.

 

In half an hour, I will go back to our house and open up a computer screen that counts the dead and the ill from around the world. That sends me a litany of messages outlining new rules and procedures. The temptation to check savings has long passed. Not that they don’t matter. It’s just that we have to cope whatever they do.

As I walk past bare trees standing tall, itching to come alive, I think of frontline workers at hospitals being asked to check incoming sickness. Surely, managers, teachers or others could take over this public-facing role? We need to protect front-line health workers, or we won’t have them by our bedside. I know of one case where a super-highly qualified nurse was thrust into the cold air without protective gear and told to check incoming. The managers hadn’t fully understood what a virus is, how it infects and what is needed to stop it, and despite advance warning from other countries they had left the hospital and staff unprepared. The nurse had to demand personal protective equipment. Thankfully, awareness is growing. The messaging is now full-on.

Isn’t it easy to fathom what we’re all scared of? The cough, the sore throat, the fever then lungs that can’t seem to get enough air into our body? The fear of our calls not being answered, of not getting tested, and where we sit on the priority list when the ventilators are all taken? The fear of not seeing your mother again because planes won’t take you there and she’s too old to be saved.

It’s the first day of spring, so the leaves have not yet shuttered the sounds of motor vehicles on nearby roads, except today that constant hum is muted. It’s quiet outside. Humanity behind curtains. As it should be, even though we could never have imagined it.

I sit down for breakfast. Oatmeal, a probiotic milk drink that has data on fighting the flu, on top of frozen fruit melted in the microwave. A tablespoon of sunflower seeds and almonds the birds didn’t get. I pop my favourite probiotic along with a multi-vitamin perhaps only to sanctify my mind. Plus, a cup of tea, of course.

I re-read what my colleague in Britain, Glenn Gibson, has compiled. A brilliant piece on why probiotics may help us fight this coronavirus. I also wrote a commentary, well-intentioned but already met with cynicism via Twitter, that communication tool that never allows enough space to say what needs to be said, and is never enough for the addicted users.

Whatever we do to fight this miniscule blob looking only to live and multiply like the rest of us, we must do it with hope. For hope is our salvation. It is what we aspire to find. And if our time here has come to an end when we least expected it, we can still leave hope for others and tell them we tried our best to shine a light in the darkness. A light that will be their future. And if more time is given to us, then surely with every ounce of energy we will welcome the horses and the blessings of Mother Nature and pass our multitude of gifts to make the world a better place.

 

When I was at high school, our English teacher from the highlands had us read a poem written around the year I was born (1955) by a famous Scot, Edwin Muir. It’s called The Horses and I will leave it for you to read (substitute ‘fathers’ for ‘parents’). For Muir, these beautiful animals were creatures closest to his God. Animals to bring hope through the hours of sadness and fear.

Barely a twelvemonth after
The seven days war that put the world to sleep,
Late in the evening the strange horses came.

By then we had made our covenant with silence,
But in the first few days it was so still
We listened to our breathing and were afraid.

On the second day
The radios failed; we turned the knobs; no answer.
On the third day a warship passed us, heading north,
Dead bodies piled on the deck. On the sixth day
A plane plunged over us into the sea. Thereafter
Nothing. The radios dumb;

And still they stand in corners of our kitchens,
And stand, perhaps, turned on, in a million rooms
All over the world. But now if they should speak,
If on a sudden they should speak again,
If on the stroke of noon, a voice should speak,
We would not listen, we would not let it bring
That old bad world that swallowed its children quick

At one great gulp. We would not have it again.

Sometimes we think of the nations lying asleep,
Curled blindly in impenetrable sorrow,
And then the thought confounds us with its strangeness.

The tractors lie about our fields; at evening
They look like dank sea-monsters couched and waiting.
We leave them where they are and let them rust:
‘They’ll molder away and be like other loam.’

We make our oxen drag our rusty plows,
Long laid aside. We have gone back
Far past our fathers’ land.

And then, that evening
Late in the summer the strange horses came.

We heard a distant tapping on the road,
A deepening drumming; it stopped, went on again
And at the corner changed to hollow thunder.

We saw the heads
Like a wild wave charging and were afraid.
We had sold our horses in our fathers’ time
To buy new tractors. Now they were strange to us
As fabulous steeds set on an ancient shield.
Or illustrations in a book of knights.

We did not dare go near them. Yet they waited,
Stubborn and shy, as if they had been sent
By an old command to find our whereabouts
And that long-lost archaic companionship.

In the first moment we had never a thought
That they were creatures to be owned and used.
Among them were some half a dozen colts
Dropped in some wilderness of the broken world,
Yet new as if they had come from their own Eden.

Since then they have pulled our plows and borne our loads
But that free servitude still can pierce our hearts.

Our life is changed; their coming our beginning.

-Edwin Muir

The science on gut microbiota and intestinal gas: Everything you wanted to know but didn’t want to ask

By Kristina Campbell, science and medical writer

Even on the days when you don’t eat a large meal of Boston baked beans, the inside of your intestines is a gas-generating factory. This serves a valuable purpose for the body when everything is working as it should, with gases being produced and eliminated through a complex set of physiological processes. But sometimes gas becomes a problem—and this is when it’s valuable to know not only what contributes to intestinal gas symptoms, but also how dietary adjustments can alleviate some of the problems.

Dr. Fernando Azpiroz, Chief of Gastrointestinal Research at the Vall d’Hebron Research Institute and Professor of Medicine, Autonomous University of Barcelona (Spain), is an expert in both the pathophysiology of the gas produced in the digestive tract and the clinical problems related to intestinal gas. Dr. Azpiroz is the author of a chapter on intestinal gas in the well-known textbook, Sleisenger and Fordtran’s Gastrointestinal and Liver Disease, which is now in its 10th edition. And for more than 20 years he has been conducting research on digestive tract function, intestinal gas, and the contributions of the gut microbiota.

ISAPP caught up with Dr. Azpiroz to ask him about everything you wanted to know—where intestinal gas comes from, when it becomes a problem, and the latest research on the dietary changes that can reduce symptoms of intestinal gas while keeping the gut microbiota intact.

In different parts of the digestive tract, where does intestinal gas come from?

For the most part, the gas in the digestive system comes from metabolic activities of the colonic microbiota.

In addition, some air enters the stomach during swallowing. Most of this air is eliminated by eructation (i.e. burping), so there is a homeostasis. There is a small air chamber in the stomach of about 20 mLs, and this is pure atmospheric air, or CO2 after recent consumption of carbonated drinks.

In the small intestine, the neutralization of acids and alkali can theoretically produce large amounts of CO2. However, it’s more in theory than measured in experimental conditions.

Other gases originate from the metabolism of the gut microbiota. The residues of the diet that are not absorbed in the small bowel pass into the colon. These are the parts of the diets that we, as humans, cannot use. These pass into the colon, and in the colon serve as substrates for colonic microbiota. Gas is produced during this process of colonic fermentation.

What types of gases are produced in the digestive tract?

The composition of intestinal gas depends on where in the gut it is produced.

In the stomach, the gas is virtually all atmospheric air or CO2.

In the small bowel, theoretically it should be CO2, although the hard data are very scarce.

And in the colon, the largest component is likely hydrogen and CO2. But the data on that are very limited, and it is not known for sure that these theories are really true. The measurements of gas composition, in the colon or even in the gas eliminated per anus are still uncertain but so far the main concept is that most of the gas is hydrogen and CO2, and methane in subjects that have a methanogenic microbiota.

How does this gas normally get eliminated?

Throughout the GI tract, particularly the colon, about 80% of the gases produced are absorbed through the mucosa, pass into the blood, and are eliminated by breath. So only about 20-25% of the volume of gases produced, particularly in the colon, are eliminated per anus.

What influences the amount of gas produced?

The amount of gas produced in different subjects depends on two factors: one is the diet—the amount of residues (i.e. fiber) in the diet—and the second is the type of microbiota, which is very individual. It varies a lot from one subject to another.

How much intestinal gas is ‘too much’?

From the point of view of patients, of symptoms, what might be relevant is the volume of gases produced, and possibly the type of gases. One evolving idea is that some gases, which are produced in very small quantities, might serve as neurotransmitters, might play a role, but so far the information we have about the role of these gases is very limited so we cannot extrapolate that to clinical use.

Very recent data indicate that symptoms occur when the GI tract has a poor tolerance to its contents, and particularly to gas.

So what is the factor that makes gas produce symptoms? Well there are two factors. One is the amount of gas, and the other one is the tolerance of the subject.

In healthy subjects, it will typically take a large amount of gas to develop symptoms, if at all.

But even small amounts of gas in patients that have a hypersensitivity of the gut and poor tolerance to contents might contribute to their symptoms. This can be seen because, if we reduce the amount of flatulogenic substances in their diet, the symptoms reduce.

This is if we just take into consideration the volume of gas produced, but there is also another factor.

If we give a high flatulogenic diet or a high-residue diet, we know, because we have measured, that we increase the volume of gas produced into the colon. However, we also increase the amount of the fecal content in the colon. So it could be that these diets produce symptoms because they increase the amount of gas, but also because other non-gaseous components, the fecal content of the colon, also are poorly tolerated.

How can someone manipulate their diet to change the amount of intestinal gas that’s produced?

A ‘challenge’ diet, or a high flatulogenic diet in healthy subjects, makes them sick. They go from being symptom-free to having some symptoms, particularly flatulence and bloating.

In patients, the effect of the diet is more accentuated. If patients consume a diet with high residues they get very symptomatic, and if these patients will reduce residues in the diet, they see quite an improvement.

What are the options for dietary change when someone has IBS or wants to reduce gas symptoms?

One thing that has been shown recently is that the effect of a low-residue diet is similar regardless of the type of diet. In the past ten years or so there’s been a major trend with the use of low-FODMAP fermentable oligo-, di-, mono-saccharides and polyols diets.

However, the effect of these complex diets is not better than the effect of any sensible and simple low-residue diet. So if you reduce legumes, veggies from the diet, and fruits, you get a similar improvement.

The problem with low-residue diets, in particular the low-FODMAP diet, is that they introduce a restriction of the substrates for the feeding of the microbiota, and this is deleterious to the microbiota. The microbiota is impoverished.

The other limitation of low-residue diet is that the moment that the patient returns to a normal diet, the symptoms come back.

There is an alternative that has been shown in the past few years, which is to use some type of prebiotics that initially—because they are fermented—produce symptoms, but after a few days they induce an adaptation of the microbiota towards a microbiota that produces less gas with normal fermentation. And down the road, these prebiotics have a positive effect on symptoms in patients. As a matter of fact, the effect on symptoms is similar to a restrictive diet. The advantage of the prebiotics is that, after interruption, …the effect is sustained at least over a few weeks. And this is because it has been shown that prebiotics serve as substrates for microbiota and induce a proliferation of beneficial organisms.

There is also some preliminary evidence that some probiotics reduce the volume of gas production and reduce digestive symptoms in patients.

Is it a good idea to test your gut microbiota when you have IBS or gas symptoms?

There are different companies that claim that by analyzing microbiota they can diagnose some functional conditions, for instance IBS. The practical application of this technology has not been demonstrated. Usually they are expensive techniques and of no value.

It’s important to understand the real value of these methodologies and take the myth out of ‘wonder’ techniques that make a diagnosis from the microbiota and claim it explains everything.

Hopefully, this might be true in the future, but not right now. And actually many of the technologies that are used for this type of analysis are suboptimal.

 A previous blog post by Dr. Bob Hutkins on diet, gut microbiota, and intestinal gas is ISAPP’s most-read blog post of all time. Read it here.

The past decade of probiotics and prebiotics research: ISAPP board members share their perspectives.

By ISAPP board members, compiled by Kristina Campbell

Scientific progress in the field of probiotics and prebiotics, as in any other field, often seems to occur one tiny step at a time. Yet over the course of several years, these tiny steps can add up to significant progress.

Current members of the ISAPP board of directors hold academic positions across North America, and Europe, representing some of the experts at the forefront of scientific innovation in probiotics and prebiotics. Their collective experience encompasses functional foods, fermentations, microbial ecology, microbial genetics, immunology, and clinical medicine, including pediatrics, family medicine and gastroenterology. As we enter into 2020 and a new decade, these board members have taken a moment to reflect on how far they and their colleagues have come over the past ten years, by answering the question: What changes have occurred in the domains of research, applications, and awareness about probiotics and prebiotics?

ISAPP board members, 2019 annual meeting

Available scientific methods and tools

The change that stood out the most to the ISAPP board members over the past decade was the rapid expansion of available scientific methods and tools – from gene sequencing technology to CRISPR-Cas to bioinformatic approaches. These exciting developments have enabled scientists to obtain more information, and to do it both quickly and economically. In the words of the board members:

“Advances in sequencing technology [have] revolutionized our ability to understand the gene repertoire of each individual probiotic strain (whole genome sequencing) and the interplay with the microbiome (metagenomics). This has been really energizing to the field, but has also meant that competence in bioinformatics has become an essential tool for probiotic and prebiotic scientists.”

“A decade ago, human studies on prebiotics would look at changes in the gut microbiota using fairly laborious procedures. Nowadays, the analysis is much more extensive and straightforward to do, and probably more accurate… The biggest change has been the capability to assess not only composition of the microbiota but also its functionality. So, today, the trials include metabonomics as well as assessments of health effects (through changes in particular symptoms and /or biomarkers such as blood lipids, microbial products, immune and inflammatory status). That way, we get a far better picture of what prebiotics can do.”

“In 2010 we only had DGGE to characterize the genome and were trying to figure out how to implement 16S amplicon sequencing. Now we are implementing shotgun & shallow shotgun sequencing for similar prices. In 2010, we did only work on 3-4 probiotic lactobacilli for molecular research, now we work on 400-500 lactobacilli. We do comparative genomics and functional analyses at much larger scale. And in 2010, we paid almost 10000 euro just to sequence one genome of lactobacilli, with limited analysis, now a few hundred euro for sequencing.”

Probiotics and prebiotics for microbiome modulation

Because of the rapid advancements in scientific tools and techniques during the past decade, as mentioned above, many more research groups are endeavoring to study the microbial communities that relate to probiotics and prebiotics. Gut microbiota are of great interest—not least because, among the strategies for microbiome modulation, probiotics and prebiotics are two of the leading candidates. Moreover, microbiome data can help researchers understand the context of probiotics and prebiotics in the gut and in different environments. In particular, many clinical trials of probiotics and prebiotics now include a microbiota-related measure. Novel species and strains for food use may be identified from gut microbiota studies, although safety and efficacy assessment will form challenges for regulatory bodies. Board members said:

“My collaborators and I initiated our first human clinical trials with prebiotics in 2008 and published several papers in 2010 and 2011. These early papers were among the first in which high throughput 16S DNA sequencing was used to assess how the human gut microbiota was affected by the prebiotic, GOS. Although this is now a routine method in the field, in 2008, having a Roche 454 pyrosequencer in the lab was very special, and we were astounded to be able to identify and measure abundances of the main members of the gut microbiota. Having these large data sets also led us to realize the importance of what was at the time the “new” field of bioinformatics that was critical in analyzing and reporting the data. This research showed that GOS was bifidogenic (with high specificity) in healthy adults, but was also subject-dependent. Thus, the results clearly showed there were prebiotic responders and non-responders. This remains an important area of research for my group.”

“The decade started with general excitement that ‘dysbiosis’ of the gut microbiota is involved in just about every human health problem, and has turned into re-remembering that correlation is not causation and microbiota patterns are often driven more by random factors or factors unrelated to disease than by microbiology.”

“It’s worth noting that in 2020, the well-controlled probiotic studies showing health benefits in humans are still more convincing and valuable than the studies showing any ‘beneficial’ effects on the human microbiota.”

“Over the past decade we have witnessed a tremendous explosion in our understanding of the microbiome and its interactions with us, its host. Progress in translating this knowledge into new treatments has been slower but glimmers of encouragement have appeared and we look forward to the next decade when interventions that modulate the microbiome to benefit our health will be based on a true understanding of how they act and will be selected to the maximal benefit of each individual.”

Probiotic mechanisms of action

Probiotic mechanisms of action are a perennial hot topic within the scientific community—and many had hoped that the new suite of scientific tools at scientists’ disposal would significantly advance this area of research during the past decade. But according to one ISAPP board member:

“In 2010 I would have confidently predicted that by 2020 we would have much more of a mechanistic understanding of probiotic mechanisms [and] the importance of strain effects… But this simply has not happened.  The field has become more biologically and computationally complex and many millions have been spent on research, but I still don’t think we can answer the fundamental question we faced in 2010, and in 2000, and in 1990 – what makes one a strain a probiotic, while another is not?”

But in the views of other board members:

“Through genomic and metabolomic studies we are identifying differences between strains that function at different sites and what properties are important for their probiotic function.”

“Identify[ing] the key effector molecules turned out to be more complex [than] we thought 10 years ago. It has become clear to me that probiotic mechanisms of action are per definition complex and multifactorial, because they are living microbes having thousands of molecules that all play a role. Yet, there is clearly an hierarchy of effector molecules.”

Probiotic and prebiotic applications

In general, microbiome studies of the past decade have led to a better appreciation of the ubiquity and complexity of microbial communities—not just those associated with different human body sites, but also those occupying every possible niche on Earth. ISAPP board members reflect:

“In 2010, I was mainly studying probiotics for the gut and vagina, now we have explored probiotics for the skin, respiratory tract, animals, plants, isolates from fermented vegetables that can boost vegan probiotic formulations etc., and other areas.”

“Two areas of research I am doing I’d never have imagined in 2010 are in honey bees and Chinook salmon and against environmental chemicals, administering probiotics.”

Public awareness of probiotics and prebiotics

Numerous studies and surveys show the general public has more awareness than ever of probiotics – and increasingly, of prebiotics too. Individuals receive their information through many different channels, both digital (e.g. blogs, websites) and non-digital (e.g. magazines, product packaging). The past decade also saw the creation of valuable evidence-based resources, such as the Clinical Guides available in the US and Canada, and resources from World Gastroenterology Organisation and from ESPGHAN (probiotics for pediatric acute gastroenteritispediatric nosocomial diarrheapreterm infants, and pediatric AAD). These resources have been enabled by a critical mass of studies that have examined the efficacy of various probiotic strains for certain indications. One board member says:

“From a clinical perspective, the biggest change for us has been that the general public knows so much about probiotics; now we are doing a lot less educating of docs and patients about the concepts behind our probiotic studies.”

But there’s still work to be done:

“The term probiotic is now widely known, but still too often people are misinterpreting what it means, or generalizing the whole field instead of recognizing strain and product differences. We need to continue to educate and clarify to keep the messaging on track.”

“There is still lack of knowledge that not all probiotics are equal. The clinical effects and safety of any single probiotic or combination of probiotics should not be extrapolated to other probiotics. The same applies to prebiotics.”

“Choosing a probiotic continues to be a major hurdle for the consumer – for every probiotic strain that is well characterized, studied in detail in appropriate disease models, and shown to be effective in clinical trials there are hundreds that would fail to pass even the most basic tests of quality control. We must help the consumer to make informed choices.”

 

It seems that, while the past decade has been a fruitful time for probiotics and prebiotics research and public awareness, scientists still have a lot of work to do. In the 2020s they will use the tools available to them, and continue to develop new ones, to gain more detailed and multi-faceted information about probiotic strains and prebiotic compounds—and about the context in which they operate (for instance, the gut microbiome), to ultimately confer benefits on human health.

Probiotics, Prebiotics and Globobiotics!

By Prof. Colin Hill, PhD, APC Microbiome Ireland, University College Cork, Ireland

Growing up I could not imagine what the world would look like in 2020, but I was convinced it would be amazing. The future was exciting, new planets and solar systems would be explored, diseases would be cured, and everyone would have sufficient food and shelter.  I sometimes think my generation may have been born at the most perfect time in human history (for someone brought up in a first world country at any rate).  We avoided the major world wars which our parents and grandparents endured, we had the benefits of cheap airfares so we could travel the world as tourists, not as armies. Oil was cheap and plentiful. Access to education was widely available. We benefited from antibiotics while they were still effective.  Gender inequalities and racism began to be addressed, even though there is still a long way to go. Computers became commonplace and the internet provided access to almost unlimited sources of information.

But here we are in 2020, and now things do not look so promising. Perhaps cynicism is a natural by-product of getting older, but now the future seems to be presented in apocalyptic terms. Climate change, antibiotic resistance, ageing populations, the paradoxes of increasing obesity and increasing hunger, exploding populations, depletion of natural resources and pollution of our oceans. Watching nature programmes hosted by the incomparable David Attenborough has changed from generating a sense of awe at the wonders of the natural world to a sense of despair as to what we are doing to it. Australia is literally on fire as I write this!  Can our planet survive the onslaught of the projected 10 billion humans by 2050 – each one hungry for a share of finite resources?  Is this really going to be the legacy from my generation to the next – a dystopian future without hope and optimism?

But it’s a New Year and a new decade, and I really want to be hopeful. I am encouraged by the fact that we are gradually beginning to come to grips with this new reality. The UN Sustainable Development Goals provide a roadmap guiding societies and individuals as to how to make a contribution. Attitudes are changing.  Too slowly for sure, but we do seem to be at a tipping point.

But what has this tirade have to do with prebiotics and probiotics, you may ask? Well, everything of course. One of the things that really gives me hope is our growing understanding of how humans are simply occupying space in a microbial world. If we squander our opportunity and destroy our planet in terms of human habitation, microbes will carry on for billions of years to come. We should remember that we can only live on Earth because all of the oxygen we breathe is the result of billions of years of microbial metabolism, that most of the carbon cycling on earth is due to microbes, and that every natural system on Earth depends on microbes. Of course we are also inhabited by a vast ecosystem of microbes (our microbiomes) that are required for our health and wellbeing, and we live in environments shaped by microbes. Understanding this will help us to live in harmony with our microbial world, rather than constantly forcing our poor planet to deliver our short term needs.

How can microbes help us to achieve sustainability and restore a healthy ecosystem? I believe that there are many opportunities. By 2050 I predict that we will be using microbes to restore productivity to land damaged by excessive use and pollution.  We will be using microbes to clean our oceans of plastic waste. We will improve food production without using chemicals, and we will have certainly reduced food waste (it is estimated that one third of all the food we produce on earth is lost to spoilage, much of it caused by microbes). We will have reduced methane emissions by manipulating the rumen microbiome in domesticated ruminants. We can look forward to a world where we can work with microbes to restore and replenish our atmosphere by unlocking the enormous potential of microbes to scavenge and store carbon. We will have reduced our reliance on antibiotics and will have found microbiome-friendly solutions to prevent and treat infection. We will have developed probiotics and prebiotics that will help us to address metabolic diseases, we will be using bacteriophage to sculpt microbiomes, while psychobiotics will be helping to prevent age related loss of brain function.

Given that the world is a microbial ecosystem, I propose that in the same way we can treat our human ecosystems with prebiotics and probiotics to improve or restore health, we can think in terms of developing microbial solutions to improve or restore planetary health. Because we haven’t had one in at least a month, I propose yet another new term; globobiotics. Globobiotics would be defined as “live microorganisms, microbial products or substrates selectively utilized by microorganisms, that are used in a manner that contributes to the sustainability of our planet”.

We’ve had the Stone Age, the Iron Age, the Oil Age, the Atomic Age and the Information Age, welcome to the Microbial Age!

ISAPP discussion group leads to new review paper providing a global perspective on the science of fermented foods and beverages

By Kristina Campbell, MSc, Science & Medical Writer

Despite the huge variety of fermented foods that have originated in countries all over the world, there are relatively few published studies describing the microbiological similarities and differences between these very diverse foods and beverages. But in recent years, thanks to the availability of high throughput sequencing and other molecular technologies combined with new computational tools, analyses of the microbes that transform fresh substrates into fermented foods are becoming more frequent.

A group of researchers from North America, Europe, and Asia gathered at the International Scientific Association for Probiotics and Prebiotics (ISAPP) 2018 conference in Singapore to discuss the science of fermented foods. Their goal was to provide a global perspective on fermented foods to account for the many  cultural, technological, and microbiological differences between east and west. This expert panel discussion culminated in a new review paper, published in Comprehensive Reviews in Food Science and Food Safety, entitled Fermented foods in a global age: East meets West.

Prof. Robert Hutkins, the paper’s lead author, says the diversity of panelists in the discussion group was an important aspect of this work. “Although we were all connected by our shared interests in fermented foods, each panelist brought a particular expertise along with different cultural backgrounds to our discussions,” he says. “Thus, one of the important outcomes, as noted in the published review paper, was how greatly historical and cultural factors, apart from microbiology, influence the types of fermented foods and beverages consumed around the world.”

The review captures the current state of knowledge on the variety of microbes that create fermented foods: whether these are starter cultures or microbes already present in the surrounding environment (i.e. the ‘authochthonous’ or ‘indigenous’ microbiota). The paper identifies general region-specific differences in the preparation of fermented foods, and the contrast between traditional and modern production of fermented foods—including the trade-offs between local and larger-scale manufacturing.

The authors of the article also took on the painstaking work of cataloging dozens of fermented foods from all over the world, including fermented milk products, fermented cereal foods, fermented vegetable products, fermented legume foods, fermented root crop foods, fermented meat foods, fermented fish products, and alcoholic beverages.

The expert panel discussions held every year at the ISAPP annual meeting provide a much-anticipated opportunity for globally leading scientists to come together to discuss issues relevant to scientific innovation and the direction of the field. This paper is an example of a concrete outcome of one of these discussion groups.

For more on fermented foods, see this ISAPP infographic or this educational video.

Maintaining a family tradition: Bulgarian whole fermented cabbage

By Mariya Petrova, PhD, Microbiome insights and Probiotics Consultancy, Karlovo, Bulgaria

Dr. Mariya Petrova with her father

November and December mark a wonderful time of the year when the cold weather makes you want to stay at home and enjoy homemade foods and drinks. However, the heavy food during the holidays makes all of us think about healthier alternatives and how to keep our gut microbiomes in check. That’s why it can be great idea to supplement your festive menu with fermented foods.

Cabbage ready to be fermented

Partly to have healthier food options at home and partly to engage in longstanding traditions, at this time of the year, millions of people in Eastern Europe roll up their sleeves, get out their knives, salt and large containers, and make fermented vegetables at home. While Western cultures are seeing fermented foods as a trendy health food option, Eastern Europeans have never forgotten how to preserve food by using natural fermentation. In my country of Bulgaria, fermented foods are simply a part of our life. Our most popular fermented foods include whole sour cabbage, pickles and pickled vegetables, yogurt, boza (a special fermented beverage), and fermented apple cider vinegar. We do not take shortcuts by pickling our vegetables with vinegar. Ours is a traditional fermentation process – add salt and then let the natural lactic acid bacteria perform their magic.

Although all of these products are interesting and delicious, the winter season brings to my mind my father’s whole cabbage fermentation. My father is busy with it every year from the beginning of November until mid-December. Whole sour cabbage is a fermented food popular not only in Bulgaria but in many of our neighboring countries such as Serbia, Macedonia, and Romania. Although similar to sauerkraut, Bulgarian whole fermented cabbage ferments the entire cabbage head, not separate cut or shredded leaves. Using whole cabbage requires both an extended period of fermentation time (around 30 to 40 days) and extra care in handling.

Preparing for fermentation

I have pictures etched in my mind of a busy local Saturday vegetable market where people would buy between 30-50 kilograms (sometimes even more) of cabbages for fermentation – depending on the size of their families. These come to life every time I hear “fermented foods” at a conference!

Cabbage and brine

But how do you ferment such a spectacular amount of cabbage? Well, first you need some rather large barrels, of course. Then you remove the outer leaves from the cabbage, core the cabbage heads, and stick them in the barrel. This is not unlike putting together a jigsaw puzzle. The cabbage heads have to be very dense without leaving to much space between them or the fermentation will not work well. The cabbage is then covered with a brine of around 2-4% salt. Finally, something heavy is placed on top of the cabbage. Many people place a heavy rock (clean of course), to keep the cabbage heads under the salty water and to allow them to ferment properly. Packing the cabbage densely and pressing it down is done to reduce oxygen to a minimum, creating an anaerobic environment for the fermentation. For better taste some people optionally add apple, quince, horseradish, and/or beetroot (which also makes the salty water more pink).

Finished fermented cabbage

Every day the salty water has to be inverted which is achieved by flushing it from the bottom of the barrel by using connected vessels and then adding it onto the top. Day-to-day shuffling of the salty water ensures a uniform distribution of microorganisms in the barrel so that all cabbage heads ferment. The best quality fermented cabbage is produced at 12-18°C temperature for around 30 days. This is why the fermentation

is done only in November – to maintain these low temperatures. Temperature from 7.5 to 18°C favors the growth and metabolism of Leuconostoc mesenteroides, while temperatures higher than 20°C favor the growth of Lactobacillus species. At higher temperatures the fermentation process takes shorter time (around 10 days), but the quality of the fermented cabbage is lower. Leuconostoc mesenteroides is essential to start the first fermentation that produces lactic acid, acetic acid, ethyl alcohol, carbon dioxide, and mannitol. All these acids, in combination with aromatic ester alcohol, contribute to the characteristic taste of high-quality sour cabbage.

Following Leuconostoc mesenteroides fermentation, Lactobacillus plantarum takes over lactic acid production, which gives a sour taste to the fermented cabbage. At the end of this Lactobacillus fermentation the cabbage is ready to enjoy as part of traditional Bulgarian cuisine. Like a special gift left by St. Nick, many people use the salted water in which the cabbage was fermenting as a drink, rich in lactic acid bacteria, and said to help digestive health.

Acknowledgment: I thank my father for showing me how to make the fermented cabbage and taking some pictures of the process this year!

Fermented foods on the holiday dinner table

Highlighting the importance of lactic acid bacteria: An interview with Prof. Seppo Salminen

By Kristina Campbell, M.Sc., science & medical writer

 

In a 2009 book called What on Earth Evolved?, British author Christopher Lloyd takes on the task of ranking the top 100 species that have influenced the planet throughout its evolutionary history.

What comes in at number 5, just slightly more influential than Homo sapiens? Lactobacilli, a diverse group of lactic-acid-producing bacteria.

The influential status of these bacteria on a global scale comes as no surprise to Prof. Seppo Salminen, ISAPP president and Professor at University of Turku (Finland), who has spent most of his career studying these microbes. He is the co-editor of the best-selling textbook Lactic Acid Bacteria: Microbiological and Functional Aspects, the fifth edition of which was released earlier this year. Salminen says the scientific community has come a long way in its understanding of lactic acid bacteria (LAB)—and in particular, lactobacilli.

Seppo Salminen at ISAPP annual meeting 2019

“If you think about the history of humankind, earlier on, more than 60% of the food supply was fermented,” explains Salminen. “On a daily basis, humans would have consumed many, many lactic acid bacteria.”

Yet 30 years ago when Salminen and his colleagues published the first edition of the textbook on lactic acid bacteria, they were working against perceptions that bacteria were universally harmful. The science on using live microorganisms to achieve health benefits was still emerging.

“Most people in food technology, they had learned how to kill bacteria but not how to keep them alive,” he explains. “They didn’t yet know how to add them to different formulations in foods and what sort of carrier they need. At that time, the safety and efficacy of probiotics was not well understood.”

Around ten years later, scientists came together to develop a definition of probiotics on behalf of the Food and Agriculture Organization of the United Nations and the WHO (FAO/WHO)—in a report that formed the basis of ISAPP Consensus meeting and today’s international consensus definition: “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host”.

With probiotics having been more precisely defined, the following years were a time of rapid scientific progress in the field. Lactobacilli became the stars of the show, as research emerged on the benefits of various strains and combinations of strains in food science and medicine.

Fast forward to today, when rapidly expanding gut microbiome research adds another dimension to what we know about these bacteria. While lactic acid bacteria are still primarily of interest for the health benefits they impart, scientists can now also study their interactions with other microorganisms in the intestinal microbiome. In some cases, this kind of research may help uncover new mechanisms of action.

After everything Salminen and his textbook co-editors (Vinderola, Ouwehand, and von Wright) have learned about lactic acid bacteria over the past few decades, Salminen says there are two main reasons for the perennial importance of the bugs. “One is their importance in food fermentation, extending the shelf life of foods, making a kind of food processing or ‘agricultural processing’ possible. To make sauerkraut shelf-stable for weeks, or to make yogurt or cheese.”

The second reason, he says, relates to their benefits for the host. “Lactic acid bacteria, especially lactobacilli, reinforce intestinal integrity. So they protect us against pathogens; and sometimes against toxins and heavy metals by binding them away.”

He continues, “The more we know, the more we understand that LAB are needed. There are very specific strains that are helpful in different conditions for animal feeds or for clinical nutrition for infants, for example.” He says the knowledge is expanding at such a rapid pace that it may only be a few more years before the textbook he co-edited will need another edition.

Salminen is currently one of the world’s most cited probiotic researchers, and has diverse ongoing research projects related to digestive health, eczema, early life, and nutrition economics—but lactic acid bacteria are the thread that weaves everything together.

“I’m proud to be working on the fifth most important factor in human evolution,” he says.

Those probiotics may actually be helping, not hurting

By Mary Ellen Sanders PhD, Executive Science Officer, ISAPP, and Gregory B. Gloor PhD, Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London

 

A recent Wall Street Journal essay posits that probiotics are harmful, but does so by misrepresenting probiotic and microbiome science in some important ways.

The focus of this essay was an anecdotal report showing that consuming probiotic products (the composition of which was not disclosed), as well as making other dietary modifications, was associated with lower fecal microbiota diversity. This equates, in the author’s mind, to an “unhealthier gut” and leads to the sensational article title “Those Probiotics May Actually Be Hurting Your ‘Gut Health’”.

How important is fecal microbiota diversity to gut health? There is no evidence in humans that increased gut microbiota diversity is causally linked to any better health outcome. In hunter-gatherer populations, the diversity of the gut microbiome cycles seasonally with diet, yet both the low and high diversity microbiomes are presumably equally ‘healthy’. Many different gut diseases are associated with microbiota compositions that differ from those from healthy subjects. But importantly, we don’t know if the different microbiota is the cause of or the result of the disease. So contrary to the author’s assertion, to speak of gut health is not to speak “really…about the gut microbiome”. Scientists don’t even know what a “healthy microbiome” looks like (see review here).

Perhaps more importantly, it is not at all surprising that consuming high numbers of a few probiotics would result in lower fecal microbial diversity. Probiotics typically survive intestinal transit and are observed in fecal samples when the microbiota is measured. A quirk of measuring the microbiome is that it is typically measured as relative abundance, and the thing about relative abundance is that as the number of one microbe goes up, others appear to decline. They don’t decline in absolute number, but their percentage of the total measured is reduced and hence our ability to detect them is also reduced. So, when you add probiotic microbes to your gut microbiota, and then measure the species present, the probiotic organisms appear at the expense of others. As illustrated in the figure, the probiotic species will appear to displace many rare species because the probiotic species comprise a high percentage of the total population. Although the other resident bacteria are all still there, they are more difficult to detect because they are now below the detection limit after probiotics were added to the community.

 

We are not aware of any evidence that probiotics will increase the diversity of fecal microbiota. In fact, based on the rationale above, we expect that probiotics may appear to decrease fecal microbiota diversity. Does that mean probiotics are harmful? No.

The author glosses over another weakness in his anecdotal report. He treats his fecal microbiota as if it is equivalent to his gut microbiota. Fecal samples represent a terminal microbial community with diminishing nutrients and many dead, but measurable, bacteria. This community is much different from what occurs farther upstream in the colon, and likely has little in common with small intestinal microbial communities. Granted, this is a weakness of much research on the gut microbiome, but discerning scientific reporting should call this what it is: fecal microbiota, not gut microbiome.

Are probiotics actually good for us? To answer this question, consult the literature that evaluates specific probiotics for the health outcome that interests you. Some good evidence exists for several clinical endpoints including antibiotic-associated diarrhea, reduced risk of C. difficile, treatment of colic in infants, reduced incidence in upper respiratory tract infections, and others (see review here).

We agree with one conclusion of the essay, that eating a diverse, whole-food, high-fiber diet likely promotes gut health. But there is nothing new about this recommendation and it seems hardly worth column space in the Wall Street Journal.

 

 

The small intestinal ‘mysteriome’: A potentially important but uncharted microbiome

By Eamonn MM Quigley MD FRCP FACP MACG FRCPI, Lynda K and David M Underwood, Center for Digestive Disorders, Division of Gastroenterology and Hepatology, Houston Methodist Hospital, Houston, Texas, USA

 

Over recent years, countless publications have documented the status of the microbiota of the gastrointestinal tract by examining fecal samples. While this approach does provide a “snapshot” or representation of what is going on in the gut, and especially in the colon, it is a crude measure of the complex interactions between micro-organisms in the gut, as well as between these same microorganisms and us (their hosts). Fecal samples comprise a terminal microbial ecosystem, characterized by depletion of readily fermentable substrates, with a concomitant change in microbial composition, even compared to those farther upstream in the colon. It is unlikely, for example, that studies using fecal samples provide a full picture of what happens when bacteria (or other microorganisms) “talk” to the lining of the gut (the mucosa) or interact with the immune system of the intestine. Even less likely is that they provide any insights into bacterial populations in the small intestine, where most of the digestion of food and absorption of nutrients takes place. The small intestine also possesses the most abundant immune tissue of the entire gastrointestinal tract.

Yet, details of which bacteria actually inhabit this long and important organ, the small intestine, are sketchy. This lack of knowledge has apparently not restricted much theorizing and speculation about the role of an overgrowth of colonic-type bacteria (referred to as small intestinal bacterial overgrowth – SIBO) in the small intestine in many symptoms, disorders, and diseases. According to one especially popular theory – the “leaky gut” hypothesis – the list of conditions is nearly endless. The “leaky gut” hypothesizes that dysbiosis in the small intestine (in other words SIBO) and a disruption of the gut barrier leads to “leakage” of bacteria and bacterial products into the circulation causing inflammation, allergy, and autoimmunity.

There are several leaps of faith involved in “leaky gut” including, of course, the definition and diagnosis of SIBO. Traditional methods of diagnosing SIBO (obtaining fluid samples directly from the upper small intestine or a variety of breath tests) are fraught with problems and, in essence, have precluded a universally accepted definition of SIBO.

Fundamental to this dilemma is the definition of the normal small intestinal microbiome – how can we diagnose abnormal when we do not know the limits of normality? I would contend that, while there are situations where it is undoubted (based on the clinical context and various laboratory and other findings) that SIBO is an issue, there are countless more instances where SIBO is over-diagnosed and incorrectly implicated as the cause of an individual’s symptoms. This is an important issue as it can lead to the inappropriate use of antibiotics – something we all wish to avoid.

There is some good news – clever techniques exist for obtaining uncontaminated fluid samples from the small intestine, a capsule technology that permits live sampling of intestinal gases (generated by bacteria) as it traverses the intestine and the application, at last, of high-throughput sequencing, metagenomics, metabolomics, and metatranscriptomics to small intestinal microbiota suggest that the accurate definition of the normal small intestinal microbiome is not far off. At that time, we can all agree on an accurate and clinically meaningful definition of SIBO.

 

Is probiotic colonization essential?

By Prof. Maria Marco, PhD, Department of Food Science & Technology, University of California, Davis

It is increasingly appreciated by consumers, physicians, and researchers alike that the human digestive tract is colonized by trillions of bacteria and many of those bacterial colonists have important roles in promoting human health. Because of this association between the gut microbiota and health, it seems appropriate to suggest that probiotics consumed in foods, beverages, or dietary supplements should also colonize the human digestive tract. But do probiotics really colonize? What is meant by the term “colonization” in the first place? If probiotics don’t colonize, does that mean that they are ineffective? In that case, should we be searching for new probiotic strains that have colonization potential?

My answer to the first question is no – probiotics generally do not colonize the digestive tract or other sites on the human body. Before leaping to conclusions on what this means for probiotic efficacy, “colonization” as defined here means the permanent, or at least long-term (weeks, months, or years) establishment at a specific body site. Colonization can also result in engraftment with consequential changes to the gut microbiota composition and function. For colonization to occur, the probiotic should multiply and form a stably replicating population. This outcome is distinct from a more transient, short-term (a few days to a week or so) persistence of a probiotic. For transient probiotics, it has been shown in numerous ways that they are metabolically active in the intestine and might even grow and divide. However, they are not expected to replicate to high numbers or displace members of the native gut microbiota.

Although some studies have shown that digestive tracts of infants can be colonized by probiotics (weeks to months), the intestinal persistence times of probiotic strains in children and adults is generally much shorter, lasting only few days. This difference is likely due to the resident gut microbiota that develops during infancy and tends to remain relatively stable throughout adulthood. Even with perturbations caused by antibiotics or foodborne illness, the gut microbiome tends to be resilient to the long-term establishment of exogenous bacterial strains. In instances where probiotic colonization or long-term persistence was found, colonization potential has been attributed more permissive gut microbiomes specific to certain individuals. In either case, for colonization to occur, any introduced probiotic has to overcome the significant ecological constraints inherent to existing, stable ecosystems.

Photo by http://benvandenbroecke.be/ Copyright, ISAPP 2019.

This leads to the next question: Can probiotics confer health benefits even if they do not colonize? My answer is definitely yes! Human studies on probiotics with positive outcomes have not relied on intestinal colonization by those microbes to cause an effect. Instead of colonizing, probiotics can alter the digestive tract in other ways such as by producing metabolites that modulate the activity of the gut microbiota or stimulate the intestinal epithelium directly. These effects could happen even on short-time scales, ranging from minutes to hours.

Should we be searching for new probiotic strains that have greater colonization potential? By extension of what we know about the resident human gut microbiota, it is increasingly attractive to identify bacteria that colonize the human digestive tract in the same way. In some situations, colonization might be preferred or even essential to impacting health, such as by engrafting a microbe that performs critical metabolic functions in the gut (e.g. break down complex carbohydrates). However, colonization also comes with risks of unintended consequences and the loss of ability to control the dose, frequency, and duration of exposure to that particular microbe.

Just as most pharmaceutical drugs have a transient impact on the human body, why should we expect more from probiotics? Many medications need to be taken life-long in order manage chronic conditions. Single or even repeated doses of any medication are similarly not expected to cure disease. Therefore, we should not assume a priori that any observed variations in probiotic efficacy are due to a lack of colonization. To the contrary, the consumption of probiotics could be sufficient for a ripple effect in the intestine, subtly altering the responses of the gut microbiome and intestinal epithelium in ways that are amplified throughout the body. Instead of aiming for engraftment directly or hand-wringing due to a lack of colonization, understanding the precise molecular interactions and cause/effect consequences of probiotic introduction will lead to a path that ultimately determines whether colonization is needed or just a distraction.

Prebiotics do better than low FODMAPs diet

By Francisco Guarner MD PhD, Consultant of Gastroenterology, Digestive System Research Unit, University Hospital Vall d’Hebron, Barcelona, Spain

Bloating and visible abdominal distention after meals is a frequent complaint of people suffering from irritable bowel syndrome, but even generally healthy people sometimes have these complaints. These symptoms are thought to be due to fermentation of food that escapes our digestive processes. Some sugars and oligosaccharides end up at the far end of our small bowel and cecum, where they become food for our resident microbes.

To manage this problem, medical organizations recommend antibiotics to suppress the microbial growth in our small intestine (known as small intestinal bacterial overgrowth or SIBO) or avoidance of foods that contain fermentable oligosaccharides, disaccharides, monosaccharides and polyols, called a low “FODMAP” diet. These approaches are generally successful in reducing symptoms, but do not provide permanent relief: symptoms typically return after the strategies are stopped.

Even worse, both approaches are known to disrupt the entire gut microbial ecosystem (not only at small bowel and cecum). Whereas a healthy microbial gut ecosystem has many different types of bacteria, antibiotics deplete them.  The low FODMAP diet deprives beneficial bacteria (such as Faecalibacterium, Roseburia, Bifidobacterium, Akkermansia, Lactobacillus and others) of the food they like to eat, and these species wane (see here).

Prof. Glenn Gibson, a founding father of prebiotic and synbiotic science, suggested that increasing ingestion of certain prebiotics could increase levels of bifidobacteria. These bifidobacteria in turn could prevent excessive gas production since they are not able to produce gas when fermenting sugars.  (Instead, bifidobacteria product short chain fatty acids, mainly lactate, which are subsequently converted to butyrate by other healthy types of bacteria, such as Faecalibacterium and Roseburia.)

Prof. Gibson’s hypothesis was tested in pilot studies where volunteers ingested a prebiotic known as galacto-oligosaccharide (Brand name: Bimuno). Healthy subjects were given 2.8 g/day of Bimuno for 3 weeks. At first, they had more gas: significantly higher number of daily anal gas evacuations than they had before taking the prebiotic (see here). The volume of gas evacuated after a test meal was also higher. However, after 3 weeks of taking the prebiotic, daily evacuations and volume of gas evacuated after the test meal returned to baseline. The microbe populations also started to recover. The relative abundance of healthy butyrate producers in fecal samples increased and correlated inversely with the volume of gas evacuated. This suggested that the prebiotic induced an adaptation of microbial metabolism, resulting in less gas.

Then researchers launched a second study, also in healthy volunteers, to look at how the metabolic activity of the microbiota changed after taking this prebiotic. They showed that adaptation to this prebiotic involves a shift in microbiota metabolism toward low-gas producing pathways (see here).

A third controlled study (randomized, parallel, double-blind), this time in patients with functional gastrointestinal disorders with flatulence, compared the effects of the prebiotic supplement (2.8 g/d Bimuno) plus a placebo diet (mediterranean-type diet) to a placebo supplement plus a diet low in FODMAPs. The study subjects were divided between these 2 diets, which they consumed for 4 weeks (see here). Both groups had statistically significant reductions in symptom scores during the 4-week intervention. Once subjects stopped taking the prebiotic, they still showed improved symptoms for 2 additional weeks (at this point, the study was completed). However, for subjects on the low-FODMAP diet, once the diet was stopped, symptoms reappeared. Very interestingly, these 2 diets had opposite effects on fecal microbiota composition. Bifidobacterium increased in the prebiotic group and decreased in the low-FODMAP group, whereas Bilophila wadsworthia (a sulfide producing species) decreased in the prebiotic group and increased in the low-FODMAP group.

The bottom line conclusion is that a diet including intermittent prebiotic administration might be an alternative to the low FODMAP diets that are currently recommended for people with functional gut symptoms, such as bloating and abdominal distention. Since low FOD MAP diets are low in fiber, the prebiotic option may provide a healthier dietary option.

 

  1. Halmos EP, Christophersen CT, Bird AR, Shepherd SJ, Gibson PR, Muir JG. Diets that differ in their FODMAP content alter the colonic luminal microenvironment. Gut. 2015;64(1):93–100.
  2. Mego M, Manichanh C, Accarino A, Campos D, Pozuelo M, Varela E, et al. Metabolic adaptation of colonic microbiota to galactooligosaccharides: a proof-of-concept-study. Aliment Pharmacol Ther. 2017;45(5):670–80.
  3. Mego M, Accarino A, Tzortzis G, Vulevic J, Gibson G, Guarner F, et al. Colonic gas homeostasis: Mechanisms of adaptation following HOST-G904 galactooligosaccharide use in humans. Neurogastroenterol Motil. 2017;29(9):e13080.
  4. Huaman J-W, Mego M, Manichanh C, Cañellas N, Cañueto D, Segurola H, et al. Effects of Prebiotics vs a Diet Low in FODMAPs in Patients With Functional Gut Disorders. Gastroenterology. 2018;155(4):1004-7.

 

Additional reading:

Halmos EP, Christophersen CT, Bird AR, Shepherd SJ, Gibson PR, Muir JG. Diets that differ in their FODMAP content alter the colonic luminal microenvironment. Gut. 2015;64(1):93–100.

Mego M, Manichanh C, Accarino A, Campos D, Pozuelo M, Varela E, et al. Metabolic adaptation of colonic microbiota to galactooligosaccharides: a proof-of-concept-study. Aliment Pharmacol Ther. 2017;45(5):670–80.

Mego M, Accarino A, Tzortzis G, Vulevic J, Gibson G, Guarner F, et al. Colonic gas homeostasis: Mechanisms of adaptation following HOST-G904 galactooligosaccharide use in humans. Neurogastroenterol Motil. 2017;29(9):e13080.

Huaman J-W, Mego M, Manichanh C, Cañellas N, Cañueto D, Segurola H, et al. Effects of Prebiotics vs a Diet Low in FODMAPs in Patients With Functional Gut Disorders. Gastroenterology. 2018;155(4):1004-7.

Halmos EP, Gibson PR. Controversies and reality of the FODMAP diet for patients with irritable bowel syndrome. J Gastroenterol Hepatol. 2019 Jul;34(7):1134-1142. doi: 10.1111/jgh.14650. Epub 2019 Apr 4.

 

 

The Children of Masiphumelele Township

Gregor Reid PhD MBA FCAHS FRSC, Professor, Western University and Scientist, Lawson Health Research Institute, London, Canada

Just off the main road from Cape Town, South Africa to Simon’s Town, sits Masiphumelele township where challenges of poverty, malnutrition, HIV and the risk of violence face people every day.

It is also the location for the Desmond Tutu HIV Foundation Youth Centre, a safe haven that provides adolescent-friendly sexual and reproductive health services alongside educational and recreational activities for youth living in Masiphumelele and surrounding areas.

To understand some of the dangers that children face, in 2017, about 270,000 people in South Africa were newly infected with HIV, adding to one of the highest HIV prevalence rates in the world. The Tutu Youth Centre aims at helping educate youth to reduce their risk of becoming another HIV statistic.

I was invited there by University of Cape Town Professor Jo-Ann Passmore, a woman not only recognized for her research but whose passion for helping others is reflected in her warm smile (4th from left in group photo). She asked if I would be interested in holding a workshop to illustrate to the youth how using sachets of probiotic bacteria could empower them. I jumped at the chance. On an afternoon break from the Keystone Symposium, thirty researchers joined me along with Jo-Ann and my wife Debbie, a teacher of children with learning disabilities.

After a tour of the areas where children learn on computers, play games in safety, or have personal discussions about sexual health, everyone filled the room with a stunning backdrop of the Nobel Laureate’s image. Having been privileged to meet the Archbishop when he was hosted by St. Joseph’s Healthcare Foundation in 2008, it was a nerve-tingling experience for me.

Giving a lecture on beneficial microbes is hard enough to peers sitting in the back of the room, but to do so with young South Africans was more somewhat daunting. However, it proved to be a lot of fun especially when we had to identify kids who were good leaders (the boys all pointed to a girl), who liked to make stuff and sell it to others (two boys stood out). By the end, we had picked the ‘staff’ of a new company.

The next step was for four groups to decide on the company’s name, what products they’d make from the probiotic sachets (the options were many including yoghurt, cereals, fruit juices, maize), what marketing tools they would use and who they would target to obtain a respectable income.

Interestingly, several of the conference participants seemed less engaged, as if they had never considered how microbiology research could affect real lives. In front of them were children facing huge challenges on a day-to-day basis. In one group, the kids were quiet until my wife brought out pens and paper, then they went to town designing products, names and labels. A lesson for me on how different people need different stimuli to become engaged. The faculty left early to beat the traffic back to Cape Town, so unfortunately, they did not hear the outcome of the children’s work.

When we re-assembled to present the results, I was impressed with what could be created in such a short time. My favourite was the Amazing Maize, a bottle shaped like a corn cob with the idea it would contain fermented maize. It emphasized the importance of marketing and for products to taste and look good to be purchased.

It has been over ten years since Archbishop Tutu applauded us for the Western Heads East project and thanked us for empowering women and youth and contributing to nutrition in Africa. Since then, thanks to the huge efforts of Western staff and students, and more recently IDRC funding and partnerships especially with Yoba-for-life, Heifer International and Jomo Kenyatta University of Agriculture and Technology, over 260,000 people in east Africa are now consuming probiotic yoghurt every week. The children of the South African townships were maybe too young to join in this new wave of microenterprises, but at least now they have heard about it and the importance of fermented food and beneficial bacteria.

In the background of the workshop several wonderful women committed to start up a new production unit using the Yoba/Fiti sachets developed by Yoba-for-life. I left them some sachets for them to try out the process.

But it was me who left with the biggest lesson on how precious each life is, and how those of us with the knowledge, need to provide the means for others to use their own talents to fulfill the purposes of their lives.

No better way than to start with the children.

I have IBS – should I have my microbiome tested?

By Prof.  Eamonn Quigley, MD. The Methodist Hospital and Weill Cornell School of Medicine, Houston

I am a gastroenterologist and specialize in what is referred to as “neurogastroenterology” – a rather grandiose term to refer to those problems that arise from disturbances in the muscles or nerves of the gut or in the communications between the brain and the gut.  Yes, the gut has its own nervous system – as elaborate as the spinal cord – which facilitates the two-way communication between the brain and gut.

The most common conditions that I deal with are termed functional gastrointestinal disorders (FGIDs) among which irritable bowel syndrome (IBS) is the most frequent. I have cared for IBS sufferers and been involved in IBS research for decades. But while much progress has been made, IBS continues to be a frustrating problem for many sufferers. No, it will not kill you, but it sure can interfere with your quality of life. Dietary changes, attention to life-style issues (including stress) and some medications can help but they do not help all sufferers all of the time. It is no wonder, therefore, that sufferers look elsewhere for relief. Because, symptoms are commonly triggered by food, there are a host of websites and practitioners offering “food allergy” testing even though there is minimal evidence that food allergy (which is a real problem, causes quite different symptoms and can be fatal) has anything to do with IBS. Nevertheless, sufferers pay hundreds of dollars out of pocket to have these worthless tests performed.

Now as I sit in clinic I am confronted by a new phenomenon – “microbiome testing”. I cringe with despair when a patient hands me pages of results of their stool microbiome analysis. Has their hard-earned money been well spent? The simple answer is NO! Let me explain. First, our knowledge of the “normal” microbiome is still in evolution so we can’t yet define what is abnormal – unless it is grossly abnormal. Second, we have learned that many factors, including diet, medications and even bowel habit can influence the microbiome.  These factors more than your underlying IBS may determine your microbiome test results.  Third, while a variety of abnormalities have been described in the microbiome in IBS sufferers, they have not been consistent. Someday we may identify a microbiome signature that diagnoses IBS or some IBS subgroups – we, simply, are not there yet. Indeed, our group, together with researchers in Ireland and the UK, are currently involved in a large study looking at diet, microbiome and other markers in an attempt to unravel these relationships in IBS.

There have been a lot of exciting developments in microbiome research over the past few years. One that has caused a lot of excitement comes from research studies showing that the microbiome can communicate with the brain (the microbiome-gut-brain axis). It is not too great a leap of faith to imagine how such communications could disturb the flow of signals between and brain and the gut and result in symptoms that typify IBS. We also know that some antibiotics and probiotics can help IBS sufferers. Indeed, about 10% of IBS suffers can date the onset of their symptoms to an episode of gastroenteritis (so-called post-infection IBS). All of this makes it likely that the microbiome has a role in IBS; what we do not know is exactly how. Is the issue a change in the microbiome? Is it how we react to our microbiome? Is it the bacteria themselves or something that they produce? Could our microbiome pattern predict what treatments we will respond to? These are fascinating and important questions which are being actively studied. In the meantime, I feel that microbiome testing in IBS (unless conducted as part of a research study) is not helpful.

If you are interested in our research study please contact me at equigley@nullhoustonmethodist.org

 

Related Reading:

Microbiome analysis: hype or helpful?

A clinician’s guide to microbiome testing

Here’s the poop on getting your gut microbiome analyzed

 

Where does our food come from – why should we care?

Dr. Karen Scott, The Rowett Institute, University of Aberdeen,  Scotland

The food we eat feeds our microbes, gives us energy and nutrition, and keeps us healthy. The choices we make about our food clearly affects our health, but also has a huge effect on the world around us. We need to make more effort to choose correctly.

Sometimes it seems that everywhere we look, someone has an opinion on what we should be eating. Television is full of programmes telling us how and what to cook – suitable for a range of abilities. In supermarkets we are continually targeted with special offers and promotions, encouraging us to buy things we do not need, that are not on our shopping list. In magazines there are page long adverts, letting us know many reasons why our lives will be enriched if we purchase product Y, and perhaps even how we will be missing out if we do not. Even newspapers print articles telling us which foods are “super” this week, and will endow us with youthful skin, long life, and/or a svelte figure. Next week there will be another article with a new superfood, and one demoting last week’s superfood to the “standard” food, or even demonising it completely.

Yet even with all this focus on what we should be eating, do we really care about where our food comes from? Shouldn’t we really be more concerned with the provenance and sustainability of our food, rather than whether it is “super”?

Quinoa is a grain with a high nutrient content, high protein content (including all nine essential amino acids) and is also a source of some essential micronutrients and vitamins. By popular measures, a “superfood”. Quinoa is primarily grown in South America (Peru, Chile and Bolivia) where it is an important dietary staple. The increased demand and resultant export of quinoa has contributed considerably to the Peruvian economy. On the other hand, the cost increases associated with the increased worldwide demand means that the local Andean population now struggle to afford to include this healthy food in their own diets. Additionally the enlarged land area now used for quinoa production has reduced the amount of land available to grow alternative crops, and this reduced diversity has a negative impact on soil quality and on wildlife. Not so “super”.

Another healthy food-fad with a negative environmental impact is avocado. The current demand for avocados as part of the ‘green smoothie’ revolution has resulted in considerable deforestation in Mexico to make way for avocado plantations. Avocado trees also need a lot of water, which, given that they are frequently grown in climates with problems of drought, is clearly not sustainable.

The other factor is price – we are constantly persuaded that we should be looking for the best deal, getting those “2-for-1 offers”, or buying our food in the specific supermarket “saving you the most on your weekly shop”. The reality is that we spend a smaller % of our income on food today than we ever have – and this is not because we eat less, far from it. But if we think about it, it is not the large supermarket that loses money when it introduces offers. Buy one get one free offers on, for example fruit, usually mean that the farmer is only getting paid for one of every two oranges sold. Is this fair? If you ask a people doing their food shopping if they think that milk should cost more than water – most people would say “yes of course”. Yet at the milk counter in the supermarket they automatically reach for the “special offer”, cheapest product. Sometimes the farmer gets paid less for the milk he sells the supermarket than it costs to produce. Again if you asked people in the shop if they thought this was fair, they would no doubt say no, but they still reach for the “special offer”, cheapest product. This is already driving smaller dairy farmers out of business. Is this what we want? We as consumers, as well as the supermarkets, have to take responsibility.

Similarly with meat products and eggs. Most people, when asked about the best and most humane ways to look after animals on farms, prefer the low density, outside methods often depicted in children’s story books. Yet when we reach the meat counter in the supermarket we are more likely to reach for the cheaper product than the one from the farm which assures humane conditions, but which may cost twice as much. Such farming methods are more expensive to run, so the products have to cost more. We have to make more effort to include our instinctive morality when we are actually making purchases of food.

We have also become accustomed to being able to buy anything, at any time of year. If we want to buy fruit that is out-of-season in our own country, it will be in-season somewhere else and can be flown across the world for display in our local supermarket. When we ask people if they care about global warming – most will agree that it is a big problem, threatening the world. Yet they will buy specific fruits or vegetables that have been flown 1000s of miles, in aeroplanes contributing CO2 emissions, without a thought. Locally produced food, eaten in season, completely avoids this non-essential contribution to global warming.

Feeding our microbes is easy – they just eat our leftovers. But perhaps we also need to think about them. Food produced in intensively farmed conditions contains more pesticide and antibiotic residues than foods produced less intensively. Depending where we live, imported foods may have fewer controls on additives and production methods than those produced locally. Although specific studies have not been carried out to gauge the effect of such residues on our microbes, it is likely that there will be an effect. The healthy compounds in fruits develop best when they are allowed to ripen on the bush/tree and are not harvested unripe and then transported across the world. Our ancestors ate fresh foods in season and produced locally. People living in remote areas of the modern world without access to the diverse range of foods in a supermarket have a more diverse, healthy microbiota than those of us consuming “western diets”. Our microbes do not need, and potentially do not want, intensively produced foods.

Many of us are in the fortunate position of being able to afford to pay a bit more for our food, and thus to support it being produced in the way we would prefer if we stopped to think about it. This is why we DO have to stop to think and not automatically reach for the cheapest product on the shelf.  If we do not support farmers who are producing food in the most humane way, they will go out of business and we will be left with no choice but to buy mass-produced, often imported, food. Is this really what we want?

We have become so accustomed to paying less for our food, and looking for bargains, that we seem to care less about the quality and provenance than the price. Unless we change our outlook we will affect whole populations and environments forever. We need to stop the disconnect between our thoughts about what our foods should be, and what we actually buy, and we need to do it before it is too late.

rdamicrobes

Recommended daily allowance (RDA) for microbes?

By Prof. Colin Hill, Alimentary Pharmabiotic Centre, Food for Health Ireland, University College Cork

In this months’ issue of The Biochemist (August 2018) I explored the concept of whether or not there could be a health benefit to ingesting large numbers of safe microbes in our diet (see the open access article here).  This was an effort, though I should stress not a scientifically rigorous effort, to consider the long history of encounters between humans and ingested microbes.

This opinion piece was prompted by a series of open questions which have often puzzled me.  Why is so much of our immune system focussed on the gut?  Why not simply let the microbes and food constituents pass through and get digested without such strict surveillance?  Surely it would be more metabolically favourable to only react to those microbes that breach our epithelial barriers?  Why does our enteric nervous system devote so much of its resources to the gut?  Why is there a generally beneficial effect of many probiotics across so many health conditions?  Why is mother’s milk designed to promote the growth of microbes?

Could the solution to all of these questions be down to a very simple answer? Because the gut ‘expects and requires’ constant encounters with microbes for full functionality. Given that humans evolved into a microbial world, and that we have consumed a diet rich in microbes for most of our evolutionary history, it makes sense that our enteric systems would be designed to appropriately deal with microbes of all types, selecting out those which can cause damage and destroying them, accommodating those which will become part of our microbiomes and letting the rest pass through.  Surely we are monitoring and controlling our ‘microbial’ organ in the same way that our eukaryotic organs are monitored and controlled.

Could it be that the rise in autoimmune diseases could be, at least in part, due to an immune system primed to expect more microbes than it currently sees?  Should we recommend that a daily dose of safe microbes should be included in dietary guidelines – in the form of more safe raw foods, more fermented foods and more probiotics? It must be emphasized that some serious pathogens must be controlled or eliminated from food – not ALL live microbes are safe. But the goal can be to process only when needed for safety reasons, so foods can be a source of the safe microbes they harbour.

Lots of questions, and not many answers.  But I for one am taking account of this concept in my daily diet and am deliberately eating more microbes – I’ll let you know how it goes!

Talking Science with ISAPP’s Science Translation Committee

By Christopher Cifelli, PhD, VP of Nutrition Research, National Dairy Council.

Communicating with others is an essential part of everyday life. We are constantly sharing information about a variety of topics with friends, family, and even strangers. Most of the time the interaction is easy and natural – and sometimes even fun. But, have you ever talked to a scientist or asked a scientist a question?

Scientists love to talk about their research. And, other scientists want other to know about their research. They enjoy expounding on the minute details of their work and can spend hours on the littlest detail. That is one trait that makes a scientist effective – the attention to detail needed to posit hypotheses and then experimentally test them in controlled, thought-out manners. Scientists can talk to other scientists easily – but, ask some of them to explain their work to the average person and it doesn’t always go so well.

ISAPP is composed of scientists that are world-renowned experts on probiotics, prebiotics, and fermented foods. And, like other scientists, ISAPP wants others to know and understand these complex topics so that they can make informed decisions that may benefit their health. The question was – how does ISAPP do that? The answer: focusing on effectively translating the science. I offered ISAPP my leadership of a new committee to take on this task. ISAPP formed the Science Translation Committee nearly 3 years ago with a goal of taking complex scientific topics and making them easy to understand for consumers and health professionals. The result of this effort has been the development of numerous infographics, blog posts, and informational videos that translate years of research into easily digestible nuggets of information that people can use. The most recent infographic focused on dispelling some common myths about probiotics – because, who doesn’t like some myth busting!

Effective science communication is essential – essential because it can help people understand the complex and enable them to make choices that can benefit their overall health. ISAPP – which is grounded in science – will continue to be the voice of probiotic and prebiotic science and work to help people understand these fun and interesting topics. So, check out our website and our resources and start learning!

blog foodomics image

Global FoodOmics: A Crowd-Sourced Window Into Microbes In Our Foods

January 25, 2018. By Mary Ellen Sanders, PhD , Dairy & Food Culture Technologies

Among the factors under our control, diet may be the most important determinant of our gut microbiota. Observations from the American Gut Project suggest that foods containing live microbes increase fecal bacterial diversity, which is generally associated with a healthy gut.

An initiative, Global FoodOmics, was launched earlier this year at the University of California San Diego under the auspices of the American Gut Project to learn more about bacteria in foods and the small molecules they produce. Dr. Julia Gauglitz is the project manager. Food samples (over 2000 have been collected to date) have been analyzed for their small molecule composition and will be tested by 16S rDNA sequencing to determine the bacterial species present. Although currently in its early stages, the aim for this project is to inventory the vast different foods consumed by people around the world.

Although many fermented foods (beer, bread, wine, kefir, many cheeses and others) rely on yeast or molds as fermentation or ripening agents, this project will aim to detect bacterial DNA, but these DNA approaches cannot distinguish between life and dead bacteria.  Labels and other descriptors accompanying submitted food samples may help determine if the species detected are likely to be alive. Fermented foods that retain live bacteria are more likely to influence our colonizing microbiota.

The small molecules being assayed are not limited to the ones produced by microbes. They may be due to microbial growth in the food (by food fermentation microbes or perhaps by spoilage or food poisoning microbes), may be innate to the food, or may be intentional or incidental (e.g., pesticides) additives to foods.

The intent is to turn Global FoodOmics into a crowd-sourced project. It will join the American Gut Project as an avenue for citizens to directly participate in science and enable the project to make all of the data publically available to other researchers and clinicians.

It is notable that this project is not the first attempt to understand the microbial components of food. Food microbiologists for decades have been assaying foods for microbes used to produce food, responsible for food spoilage and linked to food poisonings.  Recently, Prof. Bob Hutkins, University of Nebraska, on behalf of the International Scientific Association for Probiotics and Prebiotics (ISAPP) and with support from the National Dairy Council, embarked on a project to learn the state of knowledge about levels of live microbes in fermented foods. They dug into the published literature and emerged with “A survey of live microorganisms in fermented foods”, In Press at Food Microbiology. This paper gives us a summary of what is known about populations of live microbes in fermented foods, information that is very useful for people wanting to add live microbes to their diet.

Another effort to understand microbes in foods is the Consortium for Sequencing the Food Supply Chain, a partnership between IBM Research and Mars Inc. This project, focused on food safety, aims to develop a baseline of normal microbial communities in foods.

Both Global FoodOmics and the Consortium for Sequencing the Food Supply Chain will leverage modern DNA sequencing technologies to allow us better understand the microbes associated with foods. Global FoodOmics is the first project to understand the microbes and molecules in foods, by pairing small molecule metabolomics measurements with rDNA sequencing.

stool sample for lab

Microbiome Analysis – Hype or Helpful?

September 2017. By Karen Scott, PhD, Rowett Institute, University of Aberdeen, Scotland.

Since we have realized that we carry around more microbial than human cells, and that these microbial inhabitants are important to maintain our health, searching for the bacterial species that are implicated in causing disease has become the holy grail of microbiology. However, to understand which bacteria are unnaturally present or absent in a disease state, we first have to understand what constitutes normal. This is hampered by the fact that we are all different – and our microbial communities are also all different. In fact, the faecal bacterial community in samples taken months apart from one person will be identifiable as coming from that specific healthy adult, but the community will be quite distinct from samples from any other healthy adult. In the same way, the microbial community of two individuals suffering from the same disease will be different.

Despite these differences, scientists have managed to establish some facts over the past 15 years. Too many Proteobacteria, which includes Enterobacteria and E.coli, in your large intestine is not generally good news. Firstly, it means that conditions in the large intestine are probably not as anaerobic as they should be. Secondly, an expansion in these populations usually means a decline in something else – after all food and places to live are finite resources. Bacterial diversity in the adult intestine is also important. The main factor that has been found across many different diseases is that bacterial diversity is lower in diseased individuals than their healthy counterparts. This does not necessarily mean that a low diversity is causing the disease, as various features of the disease (including any antibiotic therapy, inflammation, decreased or increased transit time) may all themselves affect the diversity of the microbiota.

Although scientists have not succeeded in defining a ‘healthy microbiota,’ there is an increasing trend to get your microbiome tested. Entrepreneurial microbiome companies are bombarding us with offers to “send in a small sample and find out about your gut microbiota”. All of course, for a ‘reasonable’ price. So, should you?

This really depends why you want to know, and what level of detail of analysis is being offered. Remember the orders of taxonomy? Kingdom, phylum, class, order, family, genus, and species.  Some companies identify the bacteria in your faeces only to the phylum level. This is a taxonomic level above the level needed to differentiate mammals and fish (these are ‘classes’). If you told someone that there were more fish in the Indian Ocean than mammals would this be a surprise? It would be such an expected fact it would be meaningless. This is similar to describing the microbiota at a phylum level – Bacteroidetes numbers versus Firmicutes numbers. Such numbers are meaningless. However, continuing the fish analogy, if you said that there were more mackerel than tuna in the North Atlantic Ocean this becomes a bit more meaningful. The fisherman immediately knows what type of fish he is more likely to catch, and perhaps even which net to use. The same is true of the microbiome. Telling someone that he/she has a lot of Enterobacteria and few Roseburia is actually useful as we know from studies that this represents an abnormal balance of bacteria and something should be done to redress this. Yet the bottom line health consequence of this abnormal balance of bacteria remains to be determined. So getting your gut microbiome sequenced could be useful – depending on what level of information you will receive, and what you are prepared to do about it.

And so we come to the next problem. Having established what your gut microbiota is, how are you going to make it better? And will that make YOU better? At the moment scientists don’t really have a good answer to these questions. Specific prebiotics can certainly be useful to increase the numbers of some bacteria generally assumed to be beneficial – such as Bifidobacterium, Faecalibacterium prausnitzii and even Roseburia species. But it is not really clear what the exact health benefits of such an increase in bacterial numbers would be. Health claims on prebiotics are currently limited to ‘improve intestinal transit’ and ‘lower the glycaemic response’. If you found out that your microbiota had a low diversity, increasing the variety of foods in your diet, in particular the fibre component, could certainly improve this. Our gut microbiota basically relies on our undigested food to survive, so providing a greater amount and more types of food containing fibre and prebiotics will definitely encourage populations of diverse bacteria to expand. In addition to improving digestive health, fibre fermentation by gut bacteria also results in the production of microbial products that have been shown to have health benefits.

So by all means get your gut microbiome analyzed if you want to, but perhaps instead, save your money and just increase your prebiotic and fibre consumption, which will increase levels of the potentially beneficial bacteria that are already there in your gut.

brain-gut relationship illustration

Bugs on the Brain: the Microbiota-Gut-Brain Axis

September 2017. By Eamonn M. M. Quigley, Chief Division of Gastroenterology and Hepatology, Houston Methodist Hospital and Professor of Medicine, Weill Cornell Medical College, Houston, Texas, USA.

We can all remember those instances of diarrhea (or at least frequent bowel movements) and “butterflies” that we suffered before a critical test, interview or presentation. These are examples of stress originating from the brain influencing gut function. Extensive research over the past several decades has revealed that this is a two-way street – the gut constantly signals to the brain, too. This bidirectional channel of communication between the “big brain” in the cranium and the “little brain” (i.e. the enteric nervous system) in the gut came to be referred to as the gut-brain axis. This link relies on neurons of the sympathetic and parasympathetic nervous systems, as well as circulating hormones and other neuromodulatory molecules.

We now understand that mental symptoms of stress, anxiety or depression have a clinical impact on the gut. These include situations where the brain, the gut and their channel of communication, the autonomic nervous system, are affected by the same pathologic process. Parkinson’s disease is a prime example. Indeed, a hypothesis has evolved to suggest that Parkinson’s disease actually originates in the gut and ascends to the brain. Other scenarios include those instances where neurologic symptoms are a consequence of a primarily gastrointestinal pathology. This occurs in malabsorption syndromes when nutrients such as folic acid and B12, which are critical to brain function, become deficient. Finally, and most commonly, are those situations such as irritable bowel syndrome (IBS) where it is widely believed that symptoms result from dysfunction or disturbance somewhere along the gut-brain axis. In some individuals the problem may lie primarily in the gut; in others the main issues may be a distorted representation of gut stimuli in the brain.

Recently the concept of the gut-brain axis has been extended to include the microbiota (the microbiota-gut-brain axis) and tantalizing evidence suggests that bacteria resident in the gut could have an impact on the “big brain”. Indeed, some researchers have raced ahead to suggest that assessing alterations in the microbiome could assist in the diagnosis of a host of neurological disorders and that therapies targeted at the microbiome could play a central role in disorders as diverse as Parkinson’s disease, Alzheimer’s disease, amyotrophic lateral sclerosis, autism, stroke, depression and drug addiction.

We should remember that the microbiota-gut-brain axis is far from a novel concept as it was clearly described over 60 years ago with research on hepatic coma. Metabolic products of gut bacteria lead to this much feared complication of advanced liver disease and an intervention targeted at the microbiome, namely, the administration of antibiotics, was shown to be dramatically effective. In these pioneering studies the role of bacterial overgrowth in the small bowel by coliforms and other bacteria, which are normally confined to the colon, was found to be important. Subsequently, these same bacteria and the inflammatory response that they evoke have been incriminated in the pathophysiology of another common consequence of chronic liver disease, portal hypertension, as well as in other complications such as spontaneous bacterial peritonitis, systemic sepsis and hemostatic failure. Indeed, there are several manifestations of this tripartite resonance between microbiota, the liver and the central nervous system. Gut health factors such as small bowel bacterial overgrowth, an abnormal microbiota, impaired gut barrier function, a pro-inflammatory state and the appearance in the systemic circulation of neuro-active molecules generated by bacterial metabolism are all postulated to play important roles in the actual pathogenesis of a number of common liver diseases. So what is new?

From the basic science laboratories and a variety of animal models a pretty coherent message has emerged. Firstly, the microbiome can influence brain development, structure and function and lead to changes in cognition and behavior. Secondly, the manipulation of the microbiome – for example, with probiotics – can ameliorate certain brain disorders and reverse impaired function. Thirdly, the inoculation of microbiota samples from individuals with a number of neuropsychiatric disorders into animal models can recapitulate features of the human disease. So far so good.

As always, extrapolation from animal studies to humans is fraught with difficulties: differences between animal and human brains and microbiota, the limitations of animal models of psychiatric and functional bowel disorders, and, above all, the challenges of studying brain function in humans. The good news is that these challenges are being addressed. Researchers are utilizing various technologies that provide dynamic images of brain function in various parts of the brain in response to a variety of situations, stimuli and exposures. These are now beginning to provide evidence that our microbiota can influence brain function and that the gut microbiota might, indeed, be a therapeutic target for patients with disorders such as depression, Parkinson’s disease and autism. Data are preliminary and certainly not at a stage where we can offer diagnostic testing based on a fecal sample or recommend antibiotics, prebiotics, probiotics or fecal microbiota transplantation for a given neuropsychiatric disease or disorder. But watch this space!

kombucha

Kombucha: Trend or New Staple?

September 2017. By Prof. Bob Hutkins, Khem Shahani Professor of Food Science, University of Nebraska, Department of Food Science and Technology, Lincoln.

This blog post is adapted from a piece published by the Lincoln Journal Star. The article, first published May 4, 2016 and written by Prof. Bob Hutkins, appeared as a response to a reader’s question: “I keep hearing about kombucha… What is this stuff?”

Kombucha (pronounced kom-BOO-chuh) is made by fermenting sweetened tea using a combination of yeasts and bacteria. This mixture of live cultures that starts the fermentation is called SCOBY, short for “symbiotic colony of bacteria and yeast.” The SCOBY takes the form of a gooey mat that can be re-used for each batch or shared with friends.

Kombucha is one of many trendy fermented foods, like kimchi and kefir, that are now found everywhere. No longer just the fare of hipster cafes and posh restaurants, you can find kombucha at your local grocery store—or even at Walmart.

Kombucha’s origins go back at least 2,000 years, to China; the drink gradually spread throughout Asia and Europe. In the U.S., kits for home-brewing kombucha became available to consumers in the early 1990s, and bottled versions soon appeared on grocery store shelves.

Several factors may explain the popularity of kombucha. First, many people like the flavor: uniquely sweet and sour, with a vinegary overtone. Some ethanol (alcohol) may also be present, although commercial products must contain less than the legal limit of 0.5 percent. The fermentation reaction yields carbon dioxide, which gives kombucha a pleasant fizziness. Flavor combinations are endless, from ginger, mango, and blood orange to lavender and cinnamon.

It’s probably the suggested health properties that are most responsible for the kombucha craze. The live cultures in some blends have antimicrobial activity, which may have been valuable in past eras when antibiotics were not available. However, these properties depend on the particular mix of microbes, which varies from batch to batch or brand to brand. Other suggested health benefits range from improved gut health and digestion to treatment of cancer and other diseases. Unfortunately, there is no scientific evidence to support these health claims.

It may be that kombucha is not for everyone—the acidic nature of the drink may not sit well for some people. Microbiologists have also expressed concern that home-brewed kombucha could possibly contain toxin-producing fungi. (See related post on making safe fermented foods at home.)

Nonetheless, there’s no doubt that many consumers are drinking kombucha. Annual sales in the U.S. are over $500 million, with double-digit growth. Around half of the coveted 25-to-34 age group (i.e. millennials) are kombucha drinkers. Yes, it’s popular now, but it also seems that kombucha is likely to be around for a while.

 

Bob Hutkins is the Food Doc. He is a professor at the University of Nebraska-Lincoln, where he teaches and conducts research in food science and food microbiology. Questions on any topic related to food, food safety, food ingredients and food processing can be sent to the Food Doc at features@nulljournalstar.com.