The Committee on Diet, Nutrition, and
Cancer of the National Academy of Sciences recently evaluated the role of diet in
carcinogenesis. Both epidemiological and laboratory evidence suggests that a high intake of total fat increases susceptibility to
cancer of different sites, particularly the breast and colon. In epidemiological studies frequent consumption of certain fruits and vegetables and in laboratory experiments some components of fruits and vegetables, especially cruciferous vegetables, appear to decrease the incidence of
cancers at various sites. In contrast, frequent consumption of
salt-cured,
salt-pickled, or smoked foods, possibly because they may contain
nitrosamines or
polycyclic aromatic hydrocarbons, appears to increase the risk of esophageal or
stomach cancer. Excessive alcohol consumption among smokers appears to be associated with an elevated risk of
cancers of the oral cavity, esophagus, larynx, and respiratory tract. Interim dietary guidelines to reduce the risk of
cancer were proposed in accordance with these conclusions. No definitive conclusions were reached for other dietary factors, including total calories,
cholesterol, fiber, and
selenium, nor could the quantitative contribution of diet to overall
cancer risk be estimated.