Gut microbiota may modify the association between dietary polyphenol intake and serum concentrations of hippuric acid: results from a 1-year longitudinal study in China.

Background: Hippuric acid (HA), a host-microbe cometabolite, normally derives from gut microbial catabolism of dietary polyphenols.

Objectives: We investigated the potential interplay between dietary polyphenols and gut microbiota on circulating HA concentrations and examined the associations between serum concentrations of HA and cardiometabolic risk markers.

Methods: In a 1-y cohort of 754 community-dwelling adults, serum HA and its precursor [benzoic acid (BA)], and fecal microbiota were assayed using liquid chromatography-tandem mass spectrometry and 16S ribosomal RNA sequencing, respectively. Diet, blood pressure, blood glucose, and lipid concentrations were measured twice, 1 y apart. Arterial stiffness [indicated by brachial-ankle pulse wave velocity (baPWV) and ankle-brachial index] and liver fat accumulation [indicated by controlled attenuation parameter (CAP)] were measured after 1 y.

Results: We identified 27 microbial genera whose relative abundance was positively associated with serum HA concentrations (P < 0.05) and constructed a microbial score to reflect the overall HA-producing potential. In multivariate-adjusted linear models, dietary intake of catechins and chlorogenic acids was positively associated with serum HA concentrations among participants with a higher microbial score (β = 0.26, P = 0.03) but not among those with a lower score (β = -0.13, P = 0.30, P = 0.03). Participants with higher intake of dietary catechins and chlorogenic acids had lower triglyceride concentrations (Percentage change = -5.9%, P < 0.05). Each 1 μmol/L increase in serum HA, but not in BA, was associated with 5.7%, 1.5%, 1.7%, 1.7%, and 1.7% decrease in triglyceride, systolic blood pressure, diastolic blood pressure, baPWV, and CAP, respectively (all P < 0.05).

Conclusions: The gut microbial genera that predicted circulating HA concentrations might modify the association between dietary polyphenol intake and circulating HA concentrations, and elevated serum HA concentrations are favorably associated with multiple cardiometabolic risk markers.