Phytonutrients are secondary plant metabolites: compounds that plants produce for their own purposes including UV protection, pest defence, signalling between plants, and attraction of pollinators. Humans consuming those plants absorb these compounds, where they interact with human biology in ways that frequently reduce disease risk. The human genome evolved alongside plant phytonutrient exposure for millions of years; our cellular machinery is adapted to use these compounds in ways we are only beginning to characterise.
Key Phytonutrient Classes and Their Effects
- Flavonoids: the largest class, found in virtually all plant foods; include anthocyanins, flavonols, flavanones, and isoflavones; effects include cardiovascular protection, anti-cancer activity, and neurological protection
- Carotenoids: pigments including lycopene, beta-carotene, lutein, and zeaxanthin; protect against cardiovascular disease, age-related macular degeneration, and certain cancers
- Glucosinolates: found in cruciferous vegetables; converted to isothiocyanates including sulforaphane that activate cancer-suppressor genes and phase II detoxification enzymes
- Stilbenes: resveratrol from red grapes and berries; activates SIRT1 longevity pathways; anti-inflammatory and cardioprotective in animal studies
- Alliums: organosulphur compounds from garlic, onions, and leeks; antimicrobial, cardiovascular protective, and anti-cancer in cell studies and epidemiological research
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