Prebiotics: Does Delivery Format Matter?
By Kelly S. Swanson, PhD, University of Illinois Urbana-Champaign, USA
Prebiotics (1) have long been appreciated for their benefits to digestive function, immunity, energy balance, and metabolism. From a nutritionist’s perspective, the best way to consume dietary fibers and prebiotics is by eating a healthy diet comprising adequate amounts of whole grains, fruits, and vegetables. Prebiotic substances are naturally present in the food supply, with onions, garlic, Jerusalem artichoke, and bananas serving as rich sources. Prebiotic intake can also be boosted in other ways – in recent years, food companies have developed prebiotic-containing breakfast cereals and bars, muffin mixes, breads, and other food products. A variety of prebiotic dietary supplements are also available and may be used to complement dietary sources.
Most prebiotic substances are water soluble and have a slightly sweet flavor. These properties not only make it easy to incorporate prebiotics into food products, but beverages as well. In addition to dairy-based beverages, fruit juices, fruit and vegetable smoothies, iced teas, and others, prebiotics have been added to carbonated soft drinks. While a growing consumer interest in gut health products and expansion of the prebiotic food and beverage market is good to see, a recent class-action lawsuit against a producer of prebiotic soda has stirred up the field and prompted a few important questions.
What prebiotic dose is needed for a product to deliver a health benefit?
The ongoing lawsuit provides an interesting example in applying prebiotic science to a commercial product. To carry the prebiotic term, the prebiotic ingredient in a product must be provided at a dosage to deliver health benefits in the target host. When it comes to evaluating prebiotic-containing foods and beverages, the dosage per serving, effects of processing, format and stability of the final product, and presence of other nutrients and bioactive substances must all be considered.
The suit is based on the prebiotic dosage (2 grams of agave inulin/12-oz can) and high sugar content (4-5 grams/12-oz can) of the sodas in question, but the effects of processing and format/stability of the final product are also relevant. Based on the dosage and published scientific evidence (2, 3), consumers would need to drink 4 cans of soda to notice inulin’s benefits. Is the 2 gram dosage per can sufficient to carry the gut health claim?
How does delivery format shape the benefits of a prebiotic?
Another key variable is the delivery matrix of the prebiotic. In this case, what is the stability of the agave inulin during the processing and storage of the carbonated soda? Is it similar to that of a dry powder, a capsule, or the format tested in a previous study (i.e., chocolate candy chews) (2, 3) or is there degradation over time? Prebiotic functionality and efficacy is known to differ based on degree of polymerization, sugar composition, degree of branching, and the type of glycosidic bonds present (4). Because inulin-based prebiotics are known to be susceptible to structural degradation when exposed to high temperatures, high pressure, and/or low pH (5, 6, 7), ensuring integrity of the active prebiotic ingredient over shelf life is an important consideration with regards to product efficacy.
What other substances are present in the final product?
A final consideration is the presence of other nutrients and/or bioactive substances in the final product. The presence of essential nutrients and other substances may influence if and how prebiotics are modified during processing and impact the overall health implications of the final product. In regard to processing, prebiotics may participate in Maillard reactions during heat treatment, forming prebiotic-protein conjugates (8). These structures may increase stability and prebiotic functionality and be a benefit to a product as long as Maillard reaction products are not excessive. Other prebiotic-nutrient interactions may occur during food and beverage processing, but the area has not been well studied.
The nutrient content of the final product also has implications on health beyond that of the prebiotic effect. Prebiotic foods and beverages that contain essential nutrients, antioxidants, healthy fats, or functional fibers would be viewed as being beneficial. On the other hand, products low in essential nutrients but high in added sugar, unhealthy fats, salt, or caffeine may be viewed as being detrimental and could offset the benefits of the prebiotic.
Ensuring effective products to support gut health
In the case of the soda lawsuit, time will tell how the courts weigh the dosage and potential positives of the prebiotic vs. the negatives of the added sugar content of soda. Regardless of the outcome, it serves as a reminder to food and beverage producers interested in the biotic area. Products carrying biotic terms and/or structure-function claims pertaining to gut health must be carefully formulated and processed, with daily serving sizes providing sufficient dosages and functional activity in their final form throughout shelf life.
Further reading: Applying probiotics and prebiotics in new delivery formats – is the clinical evidence transferable?
