Whole blueberry and isolated polyphenols modulate specific gut microbes in an in vitro colon model and in human consumers. Effect of Whole blueberry and isolated polyphenol consumption on gut microbiome

Blueberry (BB) consumption is linked to improved health. Bioconversion of the polyphenolic content of blueberries by fermentative bacteria in the large intestine may be a necessary step for the health benefits attributed to BB consumption. Identification of specific gut microbiota taxa that respond to BB consumption and that mediate the bioconversion of consumed polyphenolic compounds into bioactive forms is required to improve our understanding on how polyphenols impact on human health. We tested the ability of fractions purified from whole BB, namely anthocyanins/flavonols (Anth/Flav), proanthocyanidins (PACs), the sugar/acid fraction (S/A) and total polyphenols (TPP) to modulate the faecal microbiota composition of healthy adults in an in vitro colon system. In parallel, we tested the effect of consuming 38 grams freeze-dried BB powder per day for 6 weeks on the faecal microbiota of 17 women in two age groups (i.e. young and older). BB ingredients had a distinct effect on the faecal microbiota composition in the artificial colon model. The Anth/Flav and PACs fractions were more effective in promoting microbiome alpha diversity compared to S/A and TPP, and these effects were attributed to differentially responsive taxa. Dietary enrichment with BB resulted in a moderate increase in the diversity of the microbiota of the older subjects but not in younger subjects, and certain health-relevant taxa were significantly associated with BB consumption. Alterations in abundance of some gut bacteria correlated not only with BB consumption but also with increased antioxidant activity in blood. Collectively these pilot data support the notion that BB consumption is associated with gut microbiota changes and health benefits.