A purified form of an omega 3 cuts the number and size of precancerous bowel growths (polyps) in people whose genetic make-up predisposes them to bowel cancer, finds research published ahead of print in the journal Gut.

This particular omega 3 (eicosapentaenoic acid or EPA) seems to be as effective as the prescription medicine used to treat familial bowel polyps, but without the associated cardiovascular side effects.

The researchers base their findings on 55 patients, all of whom had the inherited genetic mutation that prompts the development of precancerous polyps in the bowel - known as familial adenomatous polyposis, or FAP for short.

Twenty eight of the patients were randomly assigned to six months of treatment with 2 g daily of a new highly purified form of the omega 3 polyunsaturated fatty acid (PUFA) EPA. The other 27 were given the same amount of a dummy treatment (placebo).

The study revealed that the number of polyps increased by almost 10% among those treated with the placebo, but fell by more than 12% among those treated with the EPA capsules, representing a difference of almost 22.5%.

The authors note that the effects of EPA were similar to those produced by celecoxib, which is used to help curb the growth of new and existing polyps in patients with FAP.

The use of celecoxib has been associated with harmful cardiovascular side effects in older patients. In this study, EPA produced few side effects and these were no more common than those produced by the placebo.

This formulation of omega 3 might also help to prevent bowel cancer in people with the common non-familial form of bowel polyps, suggest the authors.

As omega 3 PUFAs in general are safe and even good for cardiovascular health, EPA could be especially suitable for older patients at risk of both bowel cancer and heart disease, they say.