● The challenge of feeding a growing population and consequent development of unsustainable industrial and agricultural practices have contributed to degradation of the environment, which negatively impacts the growth of food plants. Threats to food plants may come from living things (insects, invasive plant species, etc.) or from damaging weather and soil conditions. Many plants have genetically adapted to these stresses by producing phytonutrients that aid their growth, defense, and reproduction.
● Stressed plants synthesize higher levels of various polyphenolic phytonutrients that reduce oxidative damage, cause them to taste more bitter, or improve their resistance to drought, heat, soil salinity, and other suboptimal living circumstances. When external conditions improve, plants can reallocate their resources towards greater growth.
● This ability to self-protect with polyphenols has guided the cooperative evolution of plants as well as the humans and other living things that eat food plants. Environmental stresses alter the genetic expression of proteins that help plants synthesize polyphenols that alter immune offenses and defenses in plants as well as their consumers. This may partly account for the health benefits of plant-based diets and high intakes of fruits and vegetables. Studying how phytonutrients affect plant growth may also encourage the evolution of sustainable agricultural practices that optimize crop yields.
● This review addresses the roles of specific polyphenolic phytonutrients in guarding plants against the effects of heat and cold stress, heavy metal pollution, drought, plant predation, and competition from invasive plants. The authors describe how these polyphenols promote healthy organ function in humans by influencing immune function, cell signaling, metabolism, and stress response and antioxidant response pathways.
How Plant Polyphenols Benefit Plants—and Their Consumers
Plants elaborate polyphenolic substances to guard themselves from damage caused by adverse environmental conditions, and higher dietary intakes of these phytonutrients are associated with significant immune and metabolic health benefits. Polyphenols contribute to diversity in intestinal microbial communities and digestive health, while gut microbes enhance their health effects by transforming polyphenols into metabolites with greater bioactivity.