Pea polyphenolics and hydrolysis processing alter microbial community structure and early pathogen colonization in mice.

Health benefits associated with pea consumption have been attributed to the fiber and polyphenolic content concentrated within the pea seed coat. However, the amount of pea polyphenols can vary between cultivars, and it has yet to be studied whether pea polyphenols impact the intestinal microbiota. We hypothesized that pea polyphenols promote a healthy microbiome that supports intestinal integrity and pathogen colonization resistance. To investigate the effects of pea polyphenols, pea cultivars rich and poor in proanthocyanidins were supplemented in raw or acid hydrolyzed form to an isocaloric diet in mice. Acid hydrolysis increases the absorption of pea polyphenols by cleaving polymeric proanthocyanidins to their readily absorbable anthocyanidin monomers. After 3 weeks of diet, mice were challenged with Citrobacter rodentium and pathogen colonization and inflammation were assessed. Counter to our hypothesis, pea seed coat fraction supplementation, especially the non-hydrolyzed proanthocyanidin-rich fraction diet adversely increased C. rodentium pathogen load and inflammation. Ileal, cecal and colon microbial communities were notably distinct between pea seed cultivar and hydrolysis processing. The consumption of intact proanthocyanidins decreased microbial diversity indicating that proanthocyanidins have antimicrobial properties. Together our results indicate supplementation of raw pea seed coat rich in proanthocyanidins adversely affect intestinal integrity. However, acid hydrolysis processing restored community structure and colonization resistance, and the anthocyanidin-rich fractions reduced weight gain on a high fat diet. Establishing a clear understanding of the effects of pea fiber and polyphenolic form on health will help to develop research-based pea products and dietary recommendations.