Dietary Flavonoids: Sources, Bioavailability, and Implications for Human Health
TL;DR
Although the overall findings are encouraging, dose-response patterns, sustained effects, and causal mechanisms still require stronger clinical investigation and should therefore be viewed as potentially valuable components of preventive and personalized nutrition rather than as uniformly acting compounds.
Abstract
Flavonoids comprise a broad range of plant polyphenols present in many foods, particularly fruits, vegetables, pulses, cereals, tea, and cocoa. Their relevance to human health has been linked to several complementary actions, including modulation of oxidative balance, inflammation, immune responses, vascular function, and metabolic control. This narrative review integrates evidence on flavonoid chemistry and classification with information on food sources, absorption, biotransformation, and health-related outcomes. It considers the principal dietary groups - flavonols, flavones, flavanones, flavan-3-ols, isoflavones, and anthocyanins - together with the foods in which they commonly occur. Particular attention is given to the processes that determine systemic exposure, such as digestion, microbial conversion, interactions within the food matrix, and person-to-person metabolic variation. Population and intervention studies generally support favorable associations with cardiovascular and metabolic health, whereas conclusions concerning neurodegeneration and cancer remain less certain. The gut microbiome is increasingly recognized as both a converter of flavonoids and a target of their activity, making this reciprocal relationship relevant to individual responses. Although the overall findings are encouraging, dose-response patterns, sustained effects, and causal mechanisms still require stronger clinical investigation. Flavonoids should therefore be viewed as potentially valuable components of preventive and personalized nutrition rather than as uniformly acting compounds.