Polyunsaturated Fatty Acid Breast Cancer Risk
Omega-3 PUFAs and Vegetable Antioxidants Reduce Mammary Malignancies
Mar 5, 2009
Recent clinical and laboratory studies have suggested that dietary omega-6 polyunsaturated fatty acids (PUFAs) commonly found in vegetable oils contribute to the incidence of breast cancer. Fish oil omega-3 PUFAs can reduce the damaging effects of the omega-6 PUFAs, but the protective effects are only observed in the presence of dietary antioxidants. Thus, the advice to eat more oily fish and vegetables, is particularly relevant for breast health.
Diet and Breast Cancer
The relationship between diet and breast cancer is complex. Many of the foods that contribute to chronic inflammation, also increase the risk of breast cancer and foods that protect against inflammation, reduce breast cancer. Numerous studies have measured the impact of saturated, monounsaturated and polyunsaturated dietary fatty acids, with equivocal conclusions.
The food source of the fatty acids and available antioxidants seemed to be important. Thus, in some studies omega-3 PUFAs, such as the alpha linolenic acid (ALA) common in flax seed or the fish oil FUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), reduced cancer in human and mice, but the impact of dietary antioxidants and the omega-6 PUFA, linoleic acid (LA) proved confusing. Earlier work in cell cultures showed that all of the PUFAs suppressed the growth of cancer cells. The recent study of a large group of French women with diverse diets has clarified the interactions between dietary PUFAs, vegetable antioxidants and breast cancer.
French Study of PUFAs and Antioxidants in Breast Cancer Risk
The French study began in 1993. Approximately 100,000 women between the ages of 40 and 65 volunteered to provide dietary and breast malignancy information and about 75,000 qualified for the study (the French component of EPIC, European Investigation of Cancer and Nutrition) . The dietary data provided information on the fatty acid composition of meals and revealed who was eating vegetable antioxidants and vitamins.
Surprisingly, neither omega-6 or omega-3 fatty acids were related directly to cancer risk. Under some circumstances each group of fatty acids could contribute to high or low cancer incidence. The contribution of PUFAs to cancer risk only became clear when the ratio of omega-6 and omega-3 PUFAs was related to antioxidants.
Dietary PUFAs and Breast Cancer
Neither increasing omega-3 or omega-6 PUFAs alone was related to breast cancer, but long chain omega-3 fatty acids (EPA and DHA) could reduce breast cancer in the group of women with the highest consumption of omega-6 PUFAs. High LA or ALA consumption in the form of vegetable oils or vegetables reduced cancer incidence. It is noteworthy that high LA or ALA consumption in the form of processed foods or nuts is associated with a higher incidence of breast cancer. Longer chain PUFAs were not associated with increased risk, regardless of source.
Mediterranean Anti-Inflammatory Diet is Prudent Choice for Breast Health
The French Study emphasizes the contribution of diet to breast cancer and is consistent with the consensus that diet contributes to 50% of breast cancer risk. The fundamental requirement for inflammation in the development of all cancers and the general increase in cancer resulting from chronic inflammatory conditions, such as metabolic syndrome, leads to the conclusion that an anti-inflammatory diet should provide protection against breast cancer. The Mediterranean diet has most of the features of a general anti-inflammatory diet (low starch, high omega-3 to omega-6 PUFA ratio, high vegetable anti-oxidants, high vitamins C and D) and is consistent with the French Study.
Reference:
Thiébaut AC, Chajès V, Gerber M, Boutron-Ruault MC, Joulin V, Lenoir G, Berrino F, Riboli E, Bénichou J, Clavel-Chapelon F. 2009. Dietary intakes of omega-6 and omega-3 polyunsaturated fatty acids and the risk of breast cancer. Int J Cancer. Feb 15;124(4):924-31.
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