Major study finds potent protective effect
by Craig Weatherby
While heart disease remains the greatest health threat to American women, more than 40,000 die from breast cancer every year. October is Breast Cancer Awareness Month, and any dietary change that might reduce that risk is of keen interest to every woman: as well as to those that love them.
A study published in 2003 offers real hope of reducing breast cancer risk through diet. Researchers at the University of Southern California, working with colleagues at the National University of Singapore, examined data from the Singapore Chinese Health Study to see whether there was any relationship between dietary fats and breast cancer risk.
After reviewing the dietary diaries and medical records of the 35,298 participating women, the researchers made a very encouraging finding (key point underlined for emphasis): “Consumption of saturated, monounsaturated or polyunsaturated fat overall was unrelated to risk. On the other hand, high levels of dietary n-3 fatty acids from fish/shellfish (marine n-3 fatty acids) were significantly associated with reduced risk.” As the authors said, this is a groundbreaking study: “To our knowledge, these are the first prospective findings linking the intake of marine n-3 [omega-3] fatty acids to breast cancer protection.”
The results were adjusted to account for factors such as age, alcohol consumption, number of live births, age of regular menstruation, and family history of breast cancer.
More specifically, the study showed that postmenopausal women who consumed an average of about 1.5 to 3 ounces of fish or shellfish daily were 26 percent less likely to develop breast cancer during the study’s five year period, compared with women who ate less than one ounce of seafood per day.
The findings of The Singapore Chinese Health Study also confirmed the dangers of the extremely imbalanced intake ratio of dietary omega-3 fatty acids to omega-6 fatty acids that typifies the standard American diet. The women who consumed the least omega-3s and the most omega-6 fatty acids—i.e., the women whose diets delivered the fatty acid imbalance typical of most Americans' diets—had an 87 percent greater chance of developing breast cancer. Worse yet, their risk of being diagnosed with advanced breast cancer was more than twice the average risk (245 percent greater risk).
Of the top 10 most popular fish in the U.S., salmon and albacore tuna are the richest in omega-3 fatty acids, according to the USDA Nutrition Database.
- Gago-Dominguez M, Yuan JM, Sun CL, Lee HP, Yu MC. Opposing effects of dietary n-3 and n-6 fatty acids on mammary carcinogenesis: The Singapore Chinese Health Study. Br J Cancer. 2003 Nov 3;89(9):1686-92.