At a time when more than 40,000 American women die each year from breast cancer, there is encouraging news: eating more fatty fish has been associated with a 26% lower risk of developing this disease.
New research studies document a link between the omega-3 fatty acids found in fatty fish and a significant reduction in breast cancer risk in postmenopausal women. Breast cancer occurs most frequently in these women.
Of special importance is the "Singapore Chinese Health Study," where researchers at the Keck School of Medicine at the University of Southern California and the National University of Singapore studied the eating habits of 35,298 women aged 45 to 74 years over a five-year period. Published in the British Journal of Cancer, the study showed that postmenopausal women who consumed an average of one and a half to about 3 ounces of fish and shellfish daily were 30% less likely to develop breast cancer than women who ate less than one ounce of fish a day.
Risk reduction also was associated with marine omega-3 fatty acid consumption. These fatty acids, known as EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), are found almost exclusively in fatty fish. Based on these observations, the study authors suggested that eating approximately 40g a day -- about 10 ounces a week - - of fish and shellfish could "reduce breast cancer risk by 25%." As a comparison, the average American currently consumes less than 5 ounces of seafood per week according to National Marine Fisheries data.
Two of the essential omega-3 fatty acids found in fish are EPA and DHA. These fatty acids also have been linked to lower chance of post-partum depression, reduced possibility of premature births, and improved cognitive function in infants, among other benefits in women and their children. Of the top 10 most commonly consumed fish in this country, salmon and canned albacore tuna have the highest levels of the omega-3 fatty acid DHA, according to the U.S. Department of Agriculture (USDA) Nutrition Database.
Additional observations from the "Singapore Chinese Health Study" may explain how omega-3 fatty acids lower breast cancer risk. As reported recently in the journal Carcinogenesis, this new study links the protective effects of fish oils to breakdown products from omega-3 fatty acid metabolism. These products may have anti-cancer properties. According to the study authors, women with low-activity versions of genes for enzymes that eliminate these breakdown products also had the lowest risk of breast cancer.
"These studies offer encouragement to all American women and especially those past menopause who may be at increased risk for breast cancer," said Joyce Nettleton, D.Sc., R.D., author of Omega-3 Fatty Acids and Health and a member of the Tuna Nutrition Council. "Food choices can make a big difference. Accumulating evidence suggests that the omega-3 fatty acids in seafood may exert a protective effect against breast cancer development. A simple step like adding canned tuna and other fatty fish to the diet may reduce the chance of getting this disease. This information may help women make wiser food choices."
Besides having a protective effect against breast cancer, omega-3 fatty acids protect against heart disease and stroke and reduce the symptoms of some inflammatory conditions such as rheumatoid arthritis. Promising research also suggests these fatty acids may reduce the risk of Alzheimer's disease and maintain good cognitive function (the ability to perceive and interpret information correctly) -- especially as people age.
According to Nettleton, the average American eats about 16 pounds of fish a year, compared to about 37 pounds for the average European and over 88 pounds for the average Japanese. Many people do not eat fish at all. Recognizing the many health benefits associated with fish consumption -- including the protective effect against breast cancer -- health organizations such as the American Heart Association and the American Dietetic Association recommend that people eat two servings a week of fish, especially fatty fish.