Plant Stress Compounds: From Polyphenols to Glucosinolates

The phytonutrients that make fruits and vegetables "healthy" are, from the plant's perspective, stress-response chemicals. Plants can't run from threats, so they've evolved an extraordinary chemical defense system. Many of these defense molecules happen to activate beneficial pathways in the animals (including humans) that eat them — this is the xenohormesis framework.

How Plant Stress Increases Phytonutrient Content

UV stress increases anthocyanin and flavonoid production (sun-exposed grapes are richer in polyphenols than shaded grapes). Herbivore attack triggers glucosinolate production. Drought stress increases resveratrol in grapes. Pathogen challenge upregulates phytoalexins. Cold temperatures can increase antioxidant compounds in some plants.

Practical Implications

Wild plants, organic produce grown without synthetic pesticides, and heritage/heirloom varieties often have higher phytonutrient concentrations than conventional counterparts — partly because they've experienced more environmental stress. This is an area where "nutritious" and "conventionally efficient" farming don't always align.

The specific compounds discussed across this site — polyphenols, sulforaphane, quercetin, and many others — are all plant stress compounds that appear to trigger hormetic responses in humans.