Proceedings of the Nutrition Society

Symposium on ‘Micronutrient interactions and public health’

Micronutrients and cancer

I. T. Johnsona1 c1

a1 Institute of Food Research, Norwich Research Park, Colney, Norwich, NR4 7UA, UK

Abstract

Adverse dietary factors account for approximately 30% of all cancers. Overconsumption of energy is undoubtedly one of the major risk factors, but dietary composition is also very important. In particular, a low consumption of fruits and vegetables appears to double the risk of carcinomas of the lung and alimentary tract. Epidemiological studies suggest that high plasma levels of Se, carotenoids and ascorbic acid are protective against cancer. However, intervention studies with antioxidant nutrients have given mixed results, and it has not been established that the benefits of a high intake of fruits and vegetables are invariably related to the prevention of oxidative DNA damage. Folic acid supplementation appears to protect against colo-rectal neoplasia, probably by preventing mutations associated with the repair of uracil mis-incorporation. However, there are indications from animal studies that exposure to high levels of folic acid at certain stages of development may lead to epigenetic effects that are, as yet, poorly understood. There seems little doubt that micronutrients contribute to the protective effects of plant foods against cancers of the lung and alimentary tract, but it has not been established that these benefits can be achieved using supplements.

Correspondence:

c1 Corresponding author: I. T. Johnson, fax +44 1603 255167, email ian.johnson@bbsrc.ac.uk