Dr. Catalona’s Advice:

The Complicated Story of Omega-3 Supplements, Cardiovascular Events and Prostate Cancer

Categories: Spring 2021

Claims that omega-3 fatty acid supplements, including fish oil supplements, are an easy way to reduce the risks of heart disease have spurred their popularity. However, recent research does not support the claim that taking omega-3 supplements is an effective way to protect your heart and cardiovascular system.

In addition, Dr. Catalona advises his patients against taking these supplements due to some evidence suggesting that men with higher levels of omega-3s are more likely to develop aggressive prostate cancer.

What research has found about omega-3s and cardiovascular risks

Fish Oil pic
Omega-3 fatty acids, found in fish oils, are anti-inflammatory. Our bodies cannot make omega-3 fatty acids, which means we have to eat them.

Two recent important studies on omega-3 fatty acids found that people who took omega-3 supplements did not have lower risks of having cardiovascular events, such as heart attacks or strokes.

The STRENGTH study looked at the effect of omega-3 fatty acid supplements in people who already had high risks of having cardiovascular events. This randomized trial included more than 13,000 people who were randomly assigned to take omega-3 supplements or a placebo. Between the two groups, there were no significant differences of major cardiovascular events, such as heart attacks or strokes, after three and a half years of follow- up. The authors concluded that their trial results did not support using omega-3 fatty acid supplements to reduce these risks.

Also, the DO-HEALTH clinical trial tested whether vitamin E, omega-3s, and/or strength-training exercises improved the health of more than 2,100 older adults. The study found that none of these interventions, including omega-3s, improved blood pressure, which is indicative of cardiovascular health.

Earlier studies also had similar findings. For example, in 2019 the VITAL study of supplements found that taking omega-3 supplements did not lead to lower risks of cardiovascular events. A 2018 analysis of clinical trials looked at data of nearly 78,000 patients with a history of heart disease, stroke, or diabetes and found no association between omega-3 fatty acids and a reduced risk of heart disease or major vascular events.

I recommend that my patients discontinue taking fish oil supplements and eat a balanced diet, avoid excessive use of vitamins and supplements—everything in moderation.
-Dr. Catalona

What research has found about omega-3s and prostate cancer

A study in 2013 found that men with high concentrations of omega-3 fatty acids in their blood had a 43% greater risk of having prostate cancer, and a 71% higher risk of having high- grade prostate cancer, which is more likely to be fatal.

The study found the correlation, but by its design did not demonstrate that the fatty acids caused the cancer. The reason for the association is still unknown, but the authors suggested that fatty acids could be involved in prostate tumor development. Other factors, such as genetics, could also impact prostate cancer risk for the men in the study.

However, preliminary studies from UCLA suggest that men with certain genetic variants may actually benefit from taking fish oil supplements. Specifically, patients whose prostate tumors were infiltrated with type M2 macrophages may see a benefit if they take omega-3 supplements.

The bottom line is that there is no clear evidence that taking fish oil supplements will improve heart health, yet doing so may impact on your prostate health. Patients should talk to their doctors before they start taking fish oil supplements.

For further information on the possible link between prostate cancer and omega-3 fatty acids, search the website for articles and Q&A on “omega-3” or “fish oil.”

Subscribe to Quest

"*" indicates required fields


This email address is only for subscribing or unsubscribing to or from Quest. Dr. Catalona cannot respond to questions concerning your Personal Health Information (PHI) that could identify you as an individual. This is a "cyber-security measure" for your protection that will help prevent anyone from legally or illegally accessing your personal health information.

Delivery Method (How do you want to receive your Quest publication?)*