As a distinct grain, oat (Avena sativa L.) has been widely accepted as a key food for human health. It is becoming increasingly evident that individual differences in metabolism determine how different individuals benefit from diet. Both host genetics and the gut microbiota play important roles on the metabolism and function of dietary compounds. Recently, we used the combination of in vitro incubation assays with human gut microbiota and mouse and human S9 fractions, chemical analyses, germ-free (GF) mice, 16S rRNA sequencing, gnotobiotic techniques, and a human feeding study to pinpoint the mechanism of individual variations in response to whole grain (WG) oat intake. Our results demonstrated that gut microbiota mediates the metabolism of avenanthramides (AVAs), the signature bioactive polyphenols of WG oat, into their dihydro forms, dihydro-AVAs (DH-AVAs). We observed inter-individual variations on the metabolism of AVAs to DH-AVAs associated with Faecalibacterium prausnitzii (F. prausnitzii) relative abundance. The AVAs converting capabilities of the fecal slurries from each subject were consistent with their urinary pharmacokinetic results of DH-AVAs in a human feeding study taking oat bran as breakfast. Moreover, as opposed to GF mice, F. prausnitzii-monocolonized mice were able to metabolize AVAs to DH-AVAs. These findings demonstrate that the presence of intestinal F. prausnitzii is indispensable for proper metabolism of AVA in both human and mice. We propose that the abundance of F. prausnitzii can be used to subcategorize individuals into AVA metabolizers and non-metabolizers after WG oat intake. Our work paves the way for future explorations of how F. prausnitzii impacts the health benefits of oat intake.

The impact of gut microbiota on avenanthramide metabotype from whole grain oat intake

ACS Fall 2021

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