Diet, nutrition, and cancer: the future of dietary policy.

The long latency period of cancer would suggest that timely measures to reduce the risk of cancer, such as dietary guidelines to the public, be an integral component of policy on cancer. Although criteria for acceptability of scientific evidence are often defined, judgment its required in interpreting the significance of the evidence when the data base is incomplete. This is often the case with knowledge concerning diet and chronic diseases including cancer. Similarly, judgment is required in applying scientific data to formulate public policy recommendations. The Committee on Diet. Nutrition, and Cancer of the National Academy of Sciences/National Research Council used generally accepted criteria in evaluating the literature and proposing interim dietary guidelines to reduce the risk of cancer. A comparison of these guidelines with advice rendered to the public by other private and government organizations reveals that there are substantial areas of consensus, but important differences persist among the various groups. One major philosophical difference concerns the validity of offering advice to the general public without complete demonstration of cause and effect or absolute proof of benefit. Particularly controversial is the recommendation to modify the intake of dietary fat and its components. The immediate future of dietary policy perhaps lies in capitalizing on the areas of consensus and exploring the feasibility of developing public health programs with realistic objectives.