Polyphenols: Interesting Chemistry, Thin Clinical Evidence

Cell studies are dramatic. Bioavailability in humans is the step most claims skip over.

Polyphenols do striking things to cells in a dish at concentrations no diet produces in blood. Most are poorly absorbed and extensively transformed by gut bacteria before anything reaches tissue.

That gut transformation may be the real story, since bacterial metabolites differ between people and could explain why trials produce inconsistent results in mixed populations.

The clearest human findings are modest blood-pressure effects for cocoa flavanols and beetroot nitrate, both measured over weeks and both small.

Eating a wide range of plants remains sensible for reasons that do not depend on any of this chemistry being resolved.

Editorial note: this article summarises published research for general information. It is not medical advice. Discuss any intervention with a qualified clinician.