Human studies on the effects of fatty acids on cancer: summary, gaps, and future research

Both the goal of understanding the basic biology of cancer development as well as the practical considerations involving public health, marketing, and nutrition education have stimulated interest on the effects of individual fatty acids on cancer. Data on diet-disease relations must meet the standard of significant scientific agreement based on the totality of publicly available scientific evidence. The process of arriving at significant scientific agreement begins by collecting data accumulated from epidemiologic associations, animal studies, and clinical trials. This supplement represents one useful effort toward that end. Questions raised include: 1) What stage of the disease is being studied, what are the relevant characteristics of the study participants, how well characterized was the diet, and were appropriate experimental designs used; 2) Is there is a significant role for markers of disease and, if so, are the markers available; 3) Is there consistency, strength, and quality of evidence for establishing basic scientific relations; 4) Do dose-response relations, biological plausibility, and temporal relations (with special attention to clinical trials) exist; 5) What is the level of specificity of the data for the health claim or posited relation; and 6) What are the effective amounts of fatty acids in foods and diet? More complete food-composition data with respect to fatty acids and more comprehensive food tables are needed, as are better methods for measuring fat intakes, better markers of progression, and more definitive epidemiologic and clinical studies. At present there is insufficient evidence to conclude that specific fatty acids are associated with cancer development in humans.