But what are these prebiotic effects exactly? And does a prebiotic effect translate to a proven human health benefit? Not necessarily.
The study of dietary prebiotics is relatively new: There are few population-based studies and so more is unknown than known. Let’s take a look at what the science says about prebiotics and their health benefits.
The prebiotic effects of the aforementioned novel sources are not known. Good regulatory studies do not exist, said Joanne Slavin, a professor in the department of food science and nutrition at the University of Minnesota and an expert in the field of fiber, prebiotics and health. “If they contain oligosaccharides, they probably contain prebiotics, but there’s not enough research to know if these [particular] prebiotics have an effect.”
Prebiotics are non-digestible dietary fibers which promote the growth and activity of probiotics. The most recent definition of a dietary prebiotic comes from the International Scientific Association for Probiotics and Prebiotics working group: “Selectively fermented ingredients that result in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health.”
The dietary fibers that meet this definition (to date) are carbohydrate compounds, primarily oligosaccharides. These fibers meet all aspects of the definition of prebiotics: inulin, oligofructose, lactulose and resistant starch.
All prebiotics are dietary fibers, but not all dietary fibers are prebiotic, according to Slavin. Moderate evidence suggests that dietary fiber from whole food is essential for optimal digestive health and protects against cardiovascular disease, obesity and type 2 diabetes; however, the evidence for prebiotic intake and health is more limited.
The evidence to date
According to the article “Prebiotics and the Health Benefits of Fiber: Current Regulatory Status, Future Research, and Goals” published in The Journal of Nutrition in 2012, evidence supports prebiotics’ ability to reduce gastrointestinal infection and inflammation and increase the bioavailability and uptake of calcium. Data suggest that prebiotics may potentially decrease risk of cardiovascular disease, increase satiety, decrease risk of weight gain and reduce obesity. The U.S. Food and Drug Administration has not approved health claims for prebiotics.
There isn’t enough evidence in order to develop dietary recommendations for prebiotics, according to The Dietary Guidelines for Americans 2010 Committee. Since a daily value has not been established for prebiotics, nutrient content claims cannot be made. However, because all prebiotics are dietary fibers, researchers have suggested that a nutrient content claim for prebiotics could be argued based on dietary fiber daily values.
Health professional education
The concept of microbiota is complex, the details about prebiotics and probiotics are complicated and the research is in its infancy, so it is no wonder that many health professionals and consumers don’t have a clear understanding about what prebiotics and probiotics are and what they do.
“Registered dietitians don’t always know the difference between prebiotics and probiotics,” said Slavin. “And most consumers don’t get the concept of bacteria in the gut.”
The 2013 Food & Health Survey commissioned by the International Food Information Council Foundation found that only 34% of the 1,000-plus Americans polled believe prebiotics are associated with maintaining a healthy digestive system. In addition, 27% believe prebiotics are associated with maintenance of immune health.
“[The research] shows there’s an opportunity for education,” said Sarah Romotsky, associate director, Health & Wellness, IFIC, who also noted that there may be some confusion between the functions of prebiotics and probiotics. “Prebiotics are perceived as healthy but consumers may not know where to find them and how to incorporate them into their diet,” she added.
“In terms of spreading information to consumers, the gatekeepers are registered dietitians, home economists and the media,” noted Slavin. “But there’s no big funder or commodity group for prebiotic research and education.”
A few companies and organizations recognize the importance of investing in health professional education efforts. Slavin attended a standing-room-only prebiotic/probiotic seminar sponsored by Danone at the Experimental Biology meeting this year. And IFIC is currently updating and developing educational resources covering prebiotics and probiotics which will be available this fall at FoodInsight.org.