Specific fatty acids and risks of breast and prostate cancer: dietary intake.

Although international comparisons have suggested positive associations between consumption of total or saturated fat and risk of breast cancer, these relations have not been supported in large prospective studies in which confounding factors were minimized. There is no suggestion from international comparisons, case-control, or cohort studies that monounsaturated fat (the most abundant fat in the US diet) increases risk of breast cancer, and there is some evidence that higher intake, particularly in the form of olive oil, might actually reduce risk. The available epidemiologic evidence provides little support for any important relation between intake of either linoleic acid or extra-long-chain n-3 fatty acids from fish and risk of breast cancer. However, high consumption of linoleic acid is a relatively recent phenomenon in Western societies and continued evaluation of its relation with breast cancer risk is warranted because of animal data suggesting possible adverse effects. Ecologic, case-control, and cohort studies all support a positive relation between consumption of animal fat and risk of prostate cancer, but current evidence suggests that vegetable fat is not related to risk of this cancer. Although relevant data are limited, neither linoleic acid nor extra-long-chain n-3 fatty acid consumption appears to be related to risk of prostate cancer. Because of the strong evidence that some aspect of foods high in animal fat increases risk of prostate cancer, further studies of specific dietary fatty acids in relation to the occurrence of this malignancy are likely to be particularly valuable.