Women who consistently take fish oil supplements are significantly less likely to develop breast cancer than women who do not take fish oil, according to a 2010 study conducted by researchers from the Fred Hutchinson Cancer Research Center and published in the journal Cancer Epidemiology, Biomarkers and Prevention.
"This study is one of the largest studies that have come out showing that there may be role for fish oil in the prevention of cancer, specifically breast cancer," said Lorenzo Cohen of the University of Texas M.D. Anderson Cancer Center, who was not involved in the study.
One-third lower riskThe researchers interviewed 35,016 postmenopausal women between the ages of 50 and 76 who were taking part in the larger Vitamins and Lifestyle (VITAL) study. Participants answered questions about how recently they had taken fish oil supplements, how frequently they took them, and how long they had been taking them.
The researchers found that women who regularly took fish oil supplements were 32 percent less likely to develop ductal breast cancer than women who did not regularly take fish oil. The protective benefit was most apparent among women who had been taking fish oil for an average of 10 years.
Ductal breast cancer, which forms in the milk ducts, is the most common form of breast cancer. The study found no effect of fish oil consumption on the less common lobular breast cancer, which forms in the milk glands. No protective benefit was seen from other supplements study, including the natural menopause remedies black cohosh, dong quai, St. John's wort and soy.
Potent anti-inflammatory propertiesIt remains unclear exactly what effect the fish oil has on the development of breast cancer, particularly since other studies have not found a connection between fatty fish consumption and lower cancer rates. Some researchers believe that for anti-cancer properties to be effective, fish oil must be consumed in quantities higher than is feasible from fish consumption alone (hence the benefits seen in women who were taking supplements).
One mechanism by which fish oil may help protect against cancer is its potent anti-inflammatory effect. Inflammation is believed to play a role in the development of many chronic diseases, including cancers.
"Fish oil, in general, is a very good anti-inflammatory agent, and inflammation plays a role in cancer development," said fish oil and cancer researcher Peiying Yang of M.D. Anderson, who was not involved in the study.
Fish oil is especially high in omega-3 fatty acids, an essential nutrient that has been proven to lower the risk of heart attack and death. Omega-3s in fish oil have also been linked to improved cholesterol levels, regulation of abnormal heartbeats, and improved mental and cognitive health.
Because the quality of fish oil supplements can vary widely, Cohen cautioned consumers to purchase only from a reputable manufacturers.
"Some products may be contaminated with heavy metals," he said. "If you are not going to get fish oil from the fish itself, do appropriate homework to make sure you choose a reputable product."
