Marine Omega-3 PUFA Intake and Breast Cancer Risk
Approximately 40 years ago, Dr Kenneth Carroll and colleagues associated high fat diets with increased risk of cancer. Using national breast (and colon) cancer rates and changes in frequency as people immigrated to new regions, he established a link between total fat intake and cancer risk. These observations led to recommendations to reduce dietary fat to less than 30% of total energy intake.
A new meta-analysis and systemic review of 21 independent prospective cohort studies reports that higher consumption of dietary marine omega-3 fatty acids is associated with a lower risk of breast cancer. The 21 studies resulted in 26 publications with mean follow-up ranging from 4.3 to 20y. Overall, fish intake, α-linolenic acid (ALA) intake, and total omega-3 intake were not significantly associated with breast cancer risk. However, marine omega-3 polyunsaturated fatty acid (PUFA) was inversely associated with a relative risk (RR) of 0.86. Zheng and colleagues report marginally significant inverse associations for EPA (RR = 0.93) and DHA (RR = 0.88).
Other prospective studies have reported a protective role of omega-3 PUFA on breast cancer. The Shanghai Women’s Health Study was a prospective cohort study of 72,571 cancer-free women (40-70y). Using food frequency data over 12 months and 583,998 person-years of follow-up, Murff and colleaguesreported women with the lowest intake of marine-derived omega-3 PUFA intake and highest intake of omega-6 fatty PUFA intake had a 2-fold higher risk of breast cancer (versus highest tertile of marine-derived omega-3 PUFA and lowest tertile of omega-6 PUFA intake). They did not find significant main effect with any individual omega-6 PUFA or marine-derived omega-3 PUFA.
Using food frequency data from The VITamins and Lifestyle (VITAL) Cohort, Sczaniecka and colleaguesreported that intake of total monounsaturated fatty acids (MUFA) were associated with increased risk of breast cancer whereas total saturated fatty acids (SAT) intake was only suggestive of risk. They reported that among PUFAs, intake of EPA and DHA were inversely associated with risk of breast cancer.
Patterson and colleagues studied the diets of breast cancer survivors (n- 3,081) of the Women’s Healthy Eating and Living (WHEL) Study. They reported that women with higher DHA and EPA intakes had a 25% reduced risk of additional breast cancer events and a dose-dependent reduced risk of all-cause mortality.
It is a fitting memorial that the observations of Dr Kenneth Carroll linking dietary fat intake with breast cancer risk continue to be elucidated on July 1, Canada Day. -mm-
Carroll KK. Dietary fat and cancer. 1991 CMAJ PMC1452840
Zheng J-S, Hu X-J, Zhao Y-M, Yang J, Li D. Intake of fish and marine n-3 polyunsaturated fatty acids and risk of breast cancer: meta-analysis of data from 21 independent prospective cohort studies. 2013 BMJdoi:10.1136/mbj.f3706
Murff HJ, Shu XO, Li H, Yang G, Wu X, Cai H, et al. Dietary polyunsaturated fatty acids and breast cancer risk in Chinese women: a prospective cohort study. 2011 Int J Cancer doi:10.1002/ijc.25703
Sczaniecka AK, Brasky TM, Lampe JW, Patterson RE, White E. Dietary intake of specific fatty acids and breast cancer risk among postmenopausal women in the VITAL Cohort. 2012 Nutr Cancerdoi:10.1080/01635581.2012.718033
Patterson RE, Flatt SW, Newman VA, Natarajan L, Rock CL, Thomson CA, et al. Marine fatty acid intake is associated with breast cancer prognosis. 2011 J Nutr doi:10.3945/jn.110.128777