Fish Oil May Fight Risk of Common Breast Cancers

Jul. 8, 2010— -- Reducing breast cancer risk by nearly a third could be as easy as supplementing your diet with fish oil, new research finds.

Chock full of essential fatty acids EPA and DHA, and Omega-3, fish oil, in food or capsule-form, is often credited with bolstering heart health and brain function, but a new report from the Fred Hutchinson Cancer Research Center suggests that when taken directly as a supplement, this powerhouse oil may have another trick up its sleeve: cancer prevention.

Researchers questioned over 35,000 postmenopausal women on their use of 15 different supplements -- fish oil included -- and followed these women over the next six years.

Over that time, 880 women were diagnosed with breast cancer. While most of the supplements seemed to have no effect on breast cancer risk, those women who reported current use of fish oil supplements were less likely to develop invasive ductal breast cancer, the most common type of the disease.

"We were interested in looking at the effects of many supplements on several types of cancer," said Emily White, lead author on the report. "The citizens of the United States consume supplements more than any other country, but it seems that many of these supplements don't really do anything."

This is the first study to look specifically at the effects of fish oil supplements on cancer risk, White said, and "in general we've been surprised by our findings."

While researchers suspected that anti-oxidant supplements may play a role in cancer prevention, they were surprised to find that fish oil, an anti-inflammatory supplement, was the only one to show a significant connection to lowered breast cancer risk.

The report was published Wednesday in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.

Research Preliminary, Suggestive

While promising, these results alone do not justify a recommendation for women to take fish oil supplements as a form of cancer prevention, White cautioned.

"The evidence is supportive, but not definitive," White added.

Dr. Walter Willett, chair of the department of Nutrition at the Harvard School of Public Health, agreed, noting that past studies that have looked at fish or Omega-3 fatty acid intake and risk of breast cancer have not shown a relationship between the two.

These results do suggest that supplements may have an effect on risk, but "this does not suggest that women should start taking these supplements for prevention of breast cancer," Willet says.

While the verdict is still out on fish oil's cancer-preventing skills, the slew of other health benefits conferred by the oil could be reason enough to include it in one's diet, said Thomas Brenna, professor of Human Nutrition at Cornell University.

"I'd be taking fish oil supplements, eating seafood, for other reasons as well: to keep my brain working, my eyes working, my heart healthy. In a way, you have to question, how many different reasons do you need to keep up your consumption of fish oil or the nutrients EPA and DHA? This could provide one more reason."

Further research on these supplements is currently underway at Harvard to determine the impact of fish oil supplements and vitamin D on cancer, heart disease and stroke.

How Fish Oil Might Stave Off Cancer

Beyond fish oil's role in breast cancer prevention, White and colleagues also found a connection between fish oil supplements and a lowered risk of colorectal cancer.

Why might fish oil supplements be having this effect?

Fish oil is naturally anti-inflammatory, and some research suggests that prolonged inflammation may increase the risk of cells becoming cancerous.

"Anti-inflammatory supplements reduce the events within a cell that lead to inflammation," White says. "Specifically, by reducing inflammation, they reduce cell turnover."

Reducing this turnover is important becuase the more cells replicate, the higher the chance is that they will accumulate genetic errors -- a precursor to a cell becoming cancerous.

Thus, it is possible that reducing inflammation can lower the risk of cells becoming cancerous, White notes, though this is not yet proven.

How you get your fish oil may be an important element of the risk-reduction equation as well.

The fact that past studies failed to find a connection between dietary fish oils and breast cancer prevention may have been an issue of dose, Brenna says.

Taking fish oil in concentrated supplement form could offer a higher, more regular dose of the beneficial compounds in the oil, DHA and EPA.

"Most American diets provide only small amounts [of EPA and DHA]. It may well be that the supplements are supplying them to women whose diets are not naturally adequate in omega-3."