Cancer Prevention by Dietary Constituents in toxicological perspective.

Abstract

Diet contains a multitude of chemopreventive compounds. There are various ways of detecting the (anti)genotoxic potential of individual compounds or of whole foods ranging from short-term genotoxicity assays in vitro to epidemiological studies. There is a parallel between health risk assessment for non-carcinogens and for nongenotoxic carcinogens and health benefit effect assessment for chemopreventive agents: both imply a threshold for their effects. Toxicology indicates the lines of evidence necessary to establish a true antigenotoxic or anticarcinogenic effect in humans. One should consider four caveats: (1) an antigenotoxic potential in vitro should be verified by in vivo studies; (2) there is a lowest effect dose (threshold) below which no effect will occur; (3) beware that toxicity does not outweigh beneficial effects; and (4) (anti)carcinogens are not always (anti)mutagens and vice versa. Despite these caveats chemopreventive effects as a result of dietary intake do occur in humans. Both epidemiological evidence and evidence from experimental studies in humans is being accumulated rapidly.