Dietary fat and breast cancer.

Good reasons exist to reduce intake of animal and partially hydrogenated fat. Existing data, however, provide little support for the hypothesis that reduction in dietary fat composition, even to 20% of energy during adulthood, will lead to a substantial reduction in breast cancer in Western cultures. Some evidence suggests that substituting monounsaturated fat for other sources of energy may even reduce risk of breast cancer; this deserves further examination. Also, the avoidance of weight gain during adulthood has many benefits, which are likely to include an important reduction in risk of postmenopausal breast cancer.