title: Dietary intakes of omega-6 and omega-3 polyunsaturated fatty acids and the risk of breast cancer.
abstract: Experimental studies suggest detrimental effects of omega-6 polyunsaturated fatty acids (PUFA), and beneficial effects of omega-3 PUFAs on mammary carcinogenesis, possibly in interaction with antioxidants. However, PUFA food sources are diverse in human diets and few epidemiologic studies have examined whether associations between dietary PUFAs and breast cancer risk vary according to food sources or antioxidant intakes. The relationship between individual PUFA intakes estimated from diet history questionnaires and breast cancer risk was examined among 56,007 French women. During 8 years of follow-up, 1,650 women developed invasive breast cancer. Breast cancer risk was not related to any dietary PUFA overall; however, opposite associations were seen according to food sources, suggesting other potential effects than PUFA per se. Breast cancer risk was inversely associated with alpha-linolenic acid (ALA) intake from fruit and vegetables [highest vs. lowest quintile, hazard ratio (HR) 0.74; 95% confidence interval (CI) 0.63, 0.88; p trend < 0.0001], and from vegetable oils (HR 0.83; 95% CI 0.71, 0.97; p trend 0.017). Conversely, breast cancer risk was positively related to ALA intake from nut mixes (p trend 0.004) and processed foods (p trend 0.068), as was total ALA intake among women in the highest quintile of dietary vitamin E (p trend 0.036). A significant interaction was also found between omega-6 and long-chain omega-3 PUFAs, with breast cancer risk inversely related to long-chain omega-3 PUFAs in women belonging to the highest quintile of omega-6 PUFAs (p interaction 0.042). These results emphasize the need to consider food sources, as well as interactions between fatty acids and with antioxidants, when evaluating associations between PUFA intakes and breast cancer risk.
authors.affiliation: INSERM, ERI-20, Institut Gustave Roussy, Villejuif Cedex, France.
authors.forename: Anne C M
authors.initials: AC
authors.lastname: Thiébaut
authors.forename: Véronique
authors.initials: V
authors.lastname: Chajès
authors.forename: Mariette
authors.initials: M
authors.lastname: Gerber
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Boutron-Ruault
authors.forename: Virginie
authors.initials: V
authors.lastname: Joulin
authors.forename: Gilbert
authors.initials: G
authors.lastname: Lenoir
authors.forename: Franco
authors.initials: F
authors.lastname: Berrino
authors.forename: Elio
authors.initials: E
authors.lastname: Riboli
authors.forename: Jacques
authors.initials: J
authors.lastname: Bénichou
authors.forename: Françoise
authors.initials: F
authors.lastname: Clavel-Chapelon
mesh_terms: D000368:Aged; D000975:Antioxidants / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism / Q000517:prevention & control*; D004032:Diet; D015525:Fatty Acids, Omega-3 / Q000378:metabolism*; D043371:Fatty Acids, Omega-6 / Q000378:metabolism*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012306:Risk; D014810:Vitamin E / Q000378:metabolism; D017962:alpha-Linolenic Acid / Q000378:metabolism
chemical_list: D000975:Antioxidants; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6; D017962:alpha-Linolenic Acid; D014810:Vitamin E