Monday, 29 July 2013

Omega-3 fatty acids and an increased risk of prostate cancer? It all sounds a bit fishy.

There’ve been a number of stories in the papers recently concerning use of Omega-3 supplements increasing the risk of prostate cancer by as much as 70 per cent. We fully support all research that might bring us closer to identifying a cause for prostate cancer – especially since that will likely lead us towards better diagnosis and treatment – but it is important to get the facts straight.

The authors of the study that started these headlines found an association between men with prostate cancer and high levels of omega-3 fatty acids in their blood – fatty acid levels were generally higher in men with prostate cancer than those in the comparison group. This does not mean that high levels of Omega-3 fatty acids must therefore be the cause or indeed increase the risk of prostate cancer. I have a tennis racket sitting in my shed at home, but this doesn’t make me Andy Murray.

The finding that led to this figure of 70 per cent was that men with aggressive prostate cancer were 1.7 times more likely to have high levels of fatty acid in their blood than they were to have low levels. As all the men already had prostate cancer, this doesn’t tell us whether this association had anything to do with the men’s risk of getting cancer, or that high Omega-3 levels cause cancer. This is leap one into the unknown.

Leap two: surprisingly, especially given the media frenzy it has led to, this research never mentions Omega-3 consumption at all. We don’t know whether the men involved were taking Omega-3 supplements, or had a diet high (or even low) in oily fish. All we know is that they had high levels of fatty acids in their blood. Since we can’t tell what caused the prostate cancer in these men, we would need further trials using a valid and unbiased measurement of dietary intake to draw a reliable conclusion about any risk of prostate cancer associated with Omega-3 consumption. Although admittedly that doesn’t make such a great headline.

What’s really great about this story (although probably not what the authors intended to get from it) is how many people are now talking about prostate cancer. Although the headlines have caused a lot of worry and confusion, people in the Prostate Cancer UK online community and other prostate cancer forums are really trying to make their own minds up about this, and are sharing their thoughts and experiences.

Current research suggests there are actually a number of health benefits derived from Omega-3 fatty acids, including reduced risk of heart disease and relief for people with rheumatoid arthritis, but really the best advice when it comes to nutrition is to eat a healthy balanced diet and stay active. And not to believe everything you read in the papers.

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