Antigenotoxic activity of carotenoids in carcinogen-exposed populations

Although epidemiological studies suggest the presence of anticarcinogenic agents in the diet, it is difficult to obtain actual proof for the activity of such agents in humans. One approach is to develop and validate potential quantifiable indicators of antigenotoxic/anticarcinogenic agents which can be used in humans belonging to populations at elevated risk for cancer. This paper provides evidence that the exfoliated cell micronucleus test (MEC test) can be used (i) to provide a quantifiable marker for the amount of chromosomal breakage occurring in target tissues of carcinogen-exposed populations; (ii) to indicate the capacity of beta-carotene, alone or in combination with vitamin A, to prevent such damage; and (iii) to predict the response of other biological indicators of cancer risk, such as oral leukoplakias, in individuals receiving oral supplementation with beta-carotene/vitamin A (although the dose and time to response may differ for these endpoints). Future extensions of this approach include establishing the levels of beta-carotene required for antigenotoxic activity in a carcinogen's target tissue by concurrently measuring MEC frequencies and beta-carotene levels in exfoliated cells. In summary, early indications are that the MEC assay is an effective indicator for antigenotoxic agents in carcinogen-exposed individuals and that beta-carotene and vitamin A can suppress such genotoxic activity in at least some populations.