Diet and cancer. A review.

Diet is one of the major causes of cancer. The epidemiologic data on which this conclusion is based has been derived from analytic epidemiologic studies, buttressed by descriptive (ecologic) epidemiology and studies in experimental animals. Although the evidence is not entirely consistent, high dietary fat intake appears to be a major cause of breast cancer, and more consistently, of colorectal cancer, and probably prostate cancer as well. Obesity is an important cause of endometrial cancer, and increases the risk of breast cancer in postmenopausal women, though increasingly there is evidence that suggests that obesity is protective for breast cancer in premenopausal women. There is inconsistent evidence that dietary fibre is protective for colorectal cancer, though good evidence that vegetable consumption is protective. Several studies have pointed to a protective effect of betacarotene for lung cancer, but betacarotene may be acting as an indicator of other protective factors in diet. Recommendations for dietary modification, congruent with recommendations for the prevention of cardiovascular and other chronic diseases, are now appropriate.