Natural and human-made mutagens and carcinogens in the human diet.

With the exception of tobacco consumption, diet is probably the most important factor in the etiology of human cancer, responsible for around one third of all cases. Despite strenuous attempts in identification, no single causal factor stands out. However, high red meat consumption appears as a potential risk in a number of studies and may be important in New Zealand. Mutagens and carcinogens may be introduced to meat through preservation methods (N-nitroso compounds) and high temperature cooking (heterocyclic amines and polycyclic aromatic hydrocarbons). Mutagenic mycotoxins may be introduced to various dietary items through disease of livestock (sporidesmin) or of agricultural items leading to widespread environmental distribution (e.g. dothistromin). Debates on genetic engineering have raised the spectre of dangerous new genetic variants, but there is no proof that these have ever occurred. Many carcinogens may be endogenously generated. Lifestyle factors such as high alcohol and/or high calorie consumption may be important for some members of the population. The consumption of high fruits, vegetables and whole grain cereals are likely to be beneficial, but the relative roles of dietary fibre, micronutrients and non-nutrients as compared with whole foods is under debate. The effects of many of these dietary factors are also modulated by genotype. The increasing use of molecular genetic techniques, microarrays, proteomics, and the development of human biomonitoring methods yield the promise of gaining accurate perspectives on the relative roles of different dietary factors and genetic factors in human cancers.