Diet, nutrition, and cancer: interim dietary guidelines.

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.