Omega-3 Supplements 'Could Raise Prostate Cancer Risk'

Men who take omega-3 supplements for a health boost may be putting themselves at higher risk of prostate cancer, researchers claim.

Omega-3 fatty acids, which are found naturally in oily fish, are widely hailed for their anti-inflammatory properties which are thought to protect against a raft of maladies including heart attacks and strokes, arthritis and various cancers.

But a study found that men with high levels of omega-3 in their blood were at 43 per cent greater risk of prostate cancer than those with low concentrations, while less common aggressive “high-grade” tumours were 71 per cent more likely than in those not taking supplements.

The difference in blood concentrations of the fatty acids between the two groups was the equivalent of more than two portions of salmon per week, researchers said.

The team from Fred Hutchinson Cancer Research Center in Seattle compared blood samples from 834 prostate cancer patient against 1,393 healthy controls.

Previous studies into prostate cancer and omega-3 have produced differing results, with some suggesting the fatty acids could be protective rather than harmful, but the researchers said the new findings support an earlier paper they published in 2011.

Dr Alan Kristal, senior author of the paper, published in the Journal of the National Cancer Institute, said: “We’ve shown once again that use of nutritional supplements may be harmful.”

It is unclear why omega-3 increased the risk of the disease but the effect could be related to the body’s conversion of fatty acids into compounds which can damage cells and DNA, and suppress the immune system, researchers said.

The study did not examine how omega-3 might affect the progression of prostate cancer in men who already had the disease.

Omega-3 is one of the most popular supplements sold on the high street, with estimated sales of £116 million each year in Britain alone.

Each year around 41,000 men in the UK are diagnosed with prostate cancer and 11,000 die from the disease.

Dr Iain Frame, Director of Research at Prostate Cancer UK said: “Omega 3, such as is found in oily fish, has been the focus of a large amount of research in recent years, the majority of which points to it having wide ranging health benefits when eaten as part of a balanced diet.

“Therefore we would not encourage any man to change their diet as a result of this study, but to speak to their doctor if they have any concerns about prostate cancer.”

Sarah Williams, health information officer at Cancer Research UK, said: “The evidence as to whether omega 3 fats affect prostate cancer risk is mixed and unfortunately this study doesn’t resolve the debate. Prostate cancer is one of the most common cancers, and the risk increases as men get older."