Fish Oil Supplements Can Slow Growth of Prostate Cancer Cells

The discovery was made after testing prostate tissue samples taken from men with the disease. The scientists tested blood samples before and after the diet commenced, and examined tissue from surgically removed prostate glands.

Changes prompted by what the men were eating were clearly evident in the prostate tissue, said study leader Prof Aronson from the University of California, Los Angeles.

It was found that as little as four to six weeks on the diet was enough to reduce the growth of the cancer cells.
The same effect was not seen in men who remained on a regular Western diet with no fish oil supplements.

Professor Aronson said: 'The finding that the low-fat, fish oil diet reduced the number of rapidly dividing cells in the prostate cancer tissue is important because the rate at which the cells are dividing can be predictive of future cancer progression.
'The lower the rate of proliferation, the lesser the chances that the cancer will spread outside the prostate, where it is much harder to treat.' The findings appear in the journal Cancer Prevention Research.

Study participants on the Western diet obtained 40 per cent of their calories from fat. Food sources were typical of diets in well-off countries and included high levels of omega-6 fatty acids from corn oil. Levels of fish oil, which provide omega-3 fatty acids, were low. 
The low-fat diet relied on fat to provide just 15% of calories. Men on the diet also took five grams of fish oil per day in five capsules.

'Preclinical studies suggest that lowering dietary omega-6 fatty acids from corn oil and increasing omega-3 fatty acids from fish oil decreases the risk of prostate cancer development and progression,' the scientists wrote.
'We found this diet intervention resulted in a decrease in omega-6 versus omega-3 fatty acid ratios in benign and malignant prostate tissue and a decrease in malignant cell proliferation.'
Prof Aronson said the short duration and small size of the study meant he could not recommend dietary changes.

He is now planning a larger study of 100 men with prostate cancers who were not being actively treated but receiving regular biopsies and check-ups.

The study will take a year to evaluate the effects of a low fat diet, Western diet, or fish oil supplements on prostate cancer growth.