Summary
Del Rio and colleagues provide a comprehensive narrative review consolidating evidence on dietary polyphenols' structural diversity, absorption, and biotransformation in humans. A key finding is the substantial disparity between high concentrations used in in vitro bioactivity studies (low-μM to mM range) and the much lower nM concentrations of parent compounds and phase II metabolites that actually circulate after dietary intake, with significant quantities degraded by colonic microbiota into phenolic acids and aromatic catabolites. The authors conclude that more rigorous in vivo intervention trials and mechanistic studies are required to clarify how polyphenol metabolites and catabolites interact with human physiological processes to prevent chronic disease.
Regional applicability
The findings are applicable to UK nutrition policy and public health messaging regarding polyphenol-rich foods and chronic disease prevention. However, the review's emphasis on the gap between in vitro evidence and actual bioavailability suggests that current UK dietary guidance on polyphenol intake may need strengthening through better-designed intervention trials specific to UK populations.
Key measures
Polyphenol concentrations in plasma (nM range); phase II metabolite levels; colonic microbiota-derived catabolites; protective associations with cardiovascular disease, neurodegeneration, and cancer risk
Outcomes reported
The review synthesised evidence on the structural diversity, absorption kinetics, and biotransformation of dietary polyphenols in humans, and evaluated their protective effects against chronic diseases including cardiovascular disease, neurodegeneration, and cancer. It examined the fate of polyphenolic compounds as they pass through the gastrointestinal tract and identified gaps between in vitro bioactivity studies and actual circulating polyphenol concentrations achieved after dietary intake.
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