The study, published in the Journal of Nutrition, is said to be the first use high throughput sequencing to demonstrate a Bifidobacterium boost after agave inulin supplementation in healthy adults.
“Although Lactobacillus, Bacteroides, Roseburia, and Faecalibacterium have all demonstrated the potential to degrade oligofructose in vitro, we found that only Bifidobacterium species were selectively enriched in healthy adults who consumed agave inulin,” wrote researchers from the University of Illinois, Urbana and Ingredion Incorporated.
“Four species of Bifidobacterium were enriched with agave inulin supplementation, B. adolescentis, B. breve, B. longum, and B. pseudolongum, whereas 2 others were not (e.g., B. animalis and B. bifidum).”
The study was partly funded by Global Nutrition R&D, Ingredion, Inc.
A prebiotic is defined as a, “selectively fermented ingredient that results in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health”. (Gibson et al. Food Science and Technology Bulletin: Functional Foods, 2010, Vol. 7, pp. 1–19.)
While the new study supports the ability of agave inulin to affect the gut microbiota, more research is needed to “determine whether the observed changes translate into health benefits in human populations”, said the researchers.
Led by Kelly Swanson from the University of Illinois, Urbana, the researchers recruited 29 healthy adults to participate in their randomized, double-blind, placebo-controlled, 3-period, crossover trial. The participants were randomly assigned to one of three groups (0, 5.0, or 7.5 grams per day of agave inulin) for three weeks. These periods were followed by a seven day ‘washout period before crossing over to a different intervention.
Fecal samples were fermented and analyzed and high throughput sequencing used to determine gut bacteria populations.
Results showed that Bifidobacterium levels increased four-fold after 5.0 and 7.5 grams per day agave inulin, said the researchers, while Desulfovibrio levels decreased 40% after agave inulin consumption, compared with control.
Agave inulin consumption was also associated with reductions in the pH of the fecal samples, with butyrate levels increasing.
“The reduction in fecal pH and phenolic compounds suggests increased saccharolytic fermentation and reduced proteolytic fermentation. Because phenols and ammonia are considered toxic to intestinal epithelial cells, our results indicate a prebiotic effect of agave inulin supplementation,” they wrote.
“Next steps should include assessment of microbial functional capacity and activity through measurement of mRNA or protein expression and further assessment of untargeted bacterial metabolites,” added the researchers. “Additional characterization of bacterial crossfeeding via in vitro models and computational simulations will also help advance our understanding of the role of diet on the microbiome.
“Because rodent studies have provided evidence for the benefits of agave inulin supplementation on body composition, blood cholesterol, and blood glucose concentrations, further investigation is warranted to determine whether these effects translate into health benefits in human populations.”
Source: Journal of Nutrition
Published online ahead of print, doi: 10.3945/jn.115.217331
“Agave Inulin Supplementation Affects the Fecal Microbiota of Healthy Adults Participating in a Randomized, Double-Blind, Placebo-Controlled, Crossover Trial”
Authors: H.D. Holscher, L.L. Bauer, V. Gourineni, C.L. Pelkman, G.C. Fahey, Jr., K.S. Swanson