The importance of N-6 and N-3 fatty acids in carcinogenesis.

Cross-cultural comparisons show that total fat intake is related to breast and colon cancer mortality. Total fat consists of different fatty acid families. Therefore different fatty acids should be studied in relation to breast and colon carcinogenesis. Animal experiments suggest that N-6 polyunsaturated fatty acids may have a tumor promoting effect and that N-3 polyunsaturated fatty acids may exert an inhibitory effect on chemically-induced mammary and colon tumorigenesis. Data from epidemiologic studies in this area are scarce. Comparisons between Japan and Iceland and between Eskimos and Danes suggest that a low-fat diet in combination with a N-3/N-6 polyunsaturated fatty acid ratio of about 0.5 seems to be associated with low mortality rates from breast and colon cancer. Much more research is needed to determine the optimal intake of total fat, N-6 and N-3 polyunsaturated fatty acids in relation to breast and colon cancer prevention.