Flavonoids

Flavonoids (more than 6,000 identified) give many fruits and flowers their colours. Subgroups: flavonols (onion, tea), flavanols (cocoa, green tea), anthocyanins (berries, grapes), flavanones (citrus fruit), isoflavones (soya).

The original angle (the French paradox and cocoa): flavonoids are at the heart of the famous “French paradox“: the French, despite a diet rich in saturated fat, have relatively low rates of heart disease, partly attributed (among other factors) to the flavonoids in red wine and a diet rich in plant foods. (A caveat: alcohol remains harmful in other ways; this is not a green light for wine.)

Cocoa is a star of flavanols: dark chocolate (>70%) improves endothelial function (flexibility of the blood vessels), blood pressure and blood flow to the brain. But beware: industrial processing (alkalisation, “dutching”) destroys a large share of the flavanols, so a raw or lightly processed dark chocolate retains more.

The bioavailability angle (as with polyphenols): flavonoids are poorly absorbed directly; the microbiome transforms them into active metabolites. Their benefit therefore depends on gut health. They also act as prebiotics.

Mechanisms beyond the antioxidant: their action was thought to be purely antioxidant. In reality, they work mainly through cell signalling: they activate defence pathways (Nrf2), modulate inflammation and improve blood vessel function. The “hormetic” effect (a mild beneficial stress) outweighs the “radical sponge” effect.

To maximise your intake: eat colourful and varied food (each colour = different flavonoids), favour raw or lightly processed food, and pair it with a healthy microbiome.