Dietary fat and adult diseases and the implications for childhood nutrition: an epidemiologic approach.

Reducing dietary saturated fat by 7% of energy, a realistic target, would reduce serum cholesterol by 10% and mortality from ischemic heart disease by 25-30%. Randomized trials show that this mortality reduction is attained rapidly, usually by the third year after initial reduction of dietary saturated fat intake. Dietary change in adulthood may therefore reverse the adverse health effects of a high-fat diet in childhood. In the absence of such change, however, dietary fat in childhood may increase the risk of cardiovascular disease in adult life because of a longer duration of exposure to a high-fat diet. Assessing the effects of diet on cancer risk is more difficult. The intermediary markers of risk that are analogous to serum cholesterol are less satisfactory and there are negligible trial data. Cohort studies of diet and cancer, although subject to bias, do not favor a direct causal relation between dietary fat and cancer. But a reduction in risk is likely when dietary fat is reduced as part of a general change toward a healthier diet. The trend toward increased energy intake and body size in childhood and relatively low dietary fiber contribute to the decreasing age at menarche, which is associated with an increased risk of breast cancer. Low dietary fiber, low fruit and vegetable consumption, and high red meat consumption are associated with colon cancer and other cancers, and important causal effects of diet on cancer are likely. As with cardiovascular disease, this dietary trend that is commenced in childhood is likely to increase age-specific rates of colon cancer in adult life, but the risk may be reversed with later dietary change.