Omega 3 supplements and prostate cancer link

Omega 3 oils are one of the essential oils – our body can not make these so we must get them from our diet as they are essential for basic health. They form structural components of the brain, eye and skin and so found to be important for brain and eye development, controlling heart rhythm, reducing risk of secondary heart attack and for reducing inflammation in conditions such as psoriasis.

We find these omega 3 oils in nuts and seeds and in tiny quantities in vegetables, but in a more potent form in oily fish such as salmon, mackerel, sardines.

Current recommendations are to include oily fish weekly, but to have no more than a maximum of 2 portions a week for women of child bearing age and for girls and up to 4 times a week maximum for men and boys. The limits exist due to pollutants such as PCBs and dioxins, industrial waste products, leeching into the water systems  accumulating in oily fish. These are potential cancer causing chemcials.

 Because of the linked health benefits many people take omega 3 oils as supplements.

A recent study from the Fred Hutchinson Cancer Research Centre in Ohio compared blood samples from 834 men diagnosed with prostate cancer and 1,393 participants without the disease. They found those with prostate cancer had much higher levels of omega 3 in the blood and concluded risk was highest from those taking omega 3 supplements. They found no link from taking selenium and a negative link from vitamin E. 

Study abstract link:

Senior author of the study, Adam Kristal, noted, "The difference in blood concentrations of omega-3 fatty acids between the lowest and highest risk groups was about 2.5 percentage points  (3.2 percent vs. 5.7 percent), which is somewhat larger than the effect of eating salmon twice a week."

However it is important to note that this was an epidemiological study, which looks at trends, it can not prove cause and effect or mechanisms of action and so it is a long way off from concluding that omega 3 supplements are the cause of the link.

It is not clear what types of supplements were taken and what was in them. It may be that some other factor present in the diet or lifestyle of these patients is the causative factor and not the omega 3 at all. More research needs to be done.


For more information on current knowledge the World Cancer Research Fund (WCRF) conducts the Continuous Update Project, compiling all previous studies on cancer and diet and have so far not concluded that omega 3 oils are a significant risk factor.

The WCRF so far has only found a probable, but not convincing, increased risk from diets high in calcium and a decreased risk from lycopene. Some limited evidence has been found for intake of processed meat.

Incidence rates of prostate cancer are increasing due to better screening picking up markers much earlier. The world ranking for top 4 hIghest rates are found in Martinique, Barbados, Ireland, followed by France. 

Lycopene is abundant in tomato and red fruit, so the recommendation to include plenty of fresh vegetables and fruit and have 5 portions a day still stands as a good way forward in this area.

More information found at WCRF on this link...