Modulation of toxicity by dietary and environmental factors

Both epidemiological and experimental evidence indicate that environmental factors may modulate chemical toxicity. Of these, dietary factors have been most thoroughly studied and shown to modulate a number of toxic processes including carcinogenesis. Total energy intake and specific nutrients (protein and specific amino acids, vitamins, and minerals) have been shown to be active in this regard as have a number of non-nutritive dietary factors, most notably phenolic and sulphur-containing compounds, and indoles. The mechanisms by which dietary factors might influence toxicity include effects on bioavailability, phase I or phase II metabolism, scavenging of reactive metabolites, induction of DNA repair processes, inhibition of cell proliferation, induction of differentiation or apoptosis and effects on the immune system. These factors are discussed with emphasis on dietary exposure to modulating factors.