Omega-3s Appear to Increase Prostate Cancer Risk

A study published in the American Journal ofEpidemiology has associated omega-3 intake with an increased risk of prostate cancer-results that even surprised the researchers, who urged that their findings not be taken too seriously yet.

Researchers at Seattle’s Fred Hutchinson Cancer Research Center sought to identify any associations between prostate cancer and dietary intake of omega-3s, omega-6s, or trans fatty acids. Blood levels of each nutrient were taken from over 3000 subjects (55 to 84 years old) who participated in a 1994–2003 Prostate Cancer Prevention Trial. Participants were evaluated for prostate cancer for seven years.

“Specifically, we thought that omega-3 fatty acids would reduce and omega-6 and trans fatty acids would increase prostate cancer risk,” said lead researcher Theodore Brasky, PhD.

In fact, the results were quite the opposite. Subjects in the highest quartile of omega-3 docosahexaenoic acid (DHA) consumption were 2.5 times more likely to be diagnosed with high-grade prostate cancers than subjects with the lowest consumption. Furthermore, trans fatty acids were linearly and inversely associated with high-grade prostate cancer risk. A risk reduction of as much as 50% was observed in subjects with the highest consumption rates.

So why didn’t omega-3s-known for their anti-inflammatory properties-provide a risk reduction? The researchers proposed that omega-3s might affect biological processes related to prostate cancer beyond inflammation. They insisted that more research is warranted on this area of study.

“Overall, the beneficial effects of eating fish to prevent heart disease outweigh any harm related to prostate cancer risk,” Brasky said. “What this study shows is the complexity of nutrition and its impact on disease risk, and that we should study such associations rigorously rather than make assumptions.”