Dear Dr. Gerhart: I just saw on the news that omega-3 fatty acids and fish oil increase your risk of prostate cancer. I’ve been taking these supplements for years. How do I get tested to see if I have prostate cancer?
Dear Reader: There has been quite an uproar in the past week regarding omega-3 fatty acids. On July 10, the online edition of the Journal of the National Cancer Institute published a study in which the authors concluded that omega-3s are linked to new prostate tumors, and that those tumors are more likely to be “high-grade.” News outlets hustled to summarize the findings.
This is scary stuff on first read. Omega-3s have long been considered beneficial for their anti-inflammatory properties. Many books and health websites list them as “essential for people age 50 and older.” They have been shown to reduce inflammation in blood vessels and joints. They also help to lower triglycerides and blood pressure. Some studies even show they may help with arthritis, depression, dementia and immunity.
Before we dive into the study results, let’s clarify some terminology. The term “fish oil” is a broad term, referring to the natural fats found in fish. Within fish oils are “essential fatty acids” called omega-3 fatty acids. Three types of these acids are EPA, DPA and DHA. When you buy supplements, the label may say any of these terms (fish oil, omega-3, or EPA/DPA/DHA). However, the back of the bottle will list how much EPA, DPA and DHA the supplement contains.
So what did the study show? The study was done by scientists at Fred Hutchinson Cancer Research Center. They took 834 men with prostate cancer and 1,393 men without prostate cancer, and tested their blood for levels of omega-3s. They showed that high concentrations of omega-3s in the blood happened more often in patients with cancer than those without cancer.
The difference in the cancer group was the equivalent of about two extra servings of fish per week compared to the non-cancer group. Also, the majority of the patients in both groups did not take extra omega-3 supplements. Their blood levels were mainly from dietary omega-3s.
But just because increased levels of omega-3s may correlate with those who have prostate cancer, it doesn’t mean the omega-3s actually caused the cancer. The study didn’t look to see what the omega-3 levels were in the patients before they got cancer. It’s possible that those with prostate cancer are trying to eat a healthier “anti-inflammatory” diet and, therefore, included more fish or fish oil in their diet at the time of the blood testing.
Furthermore, the amount of omega-3s in fish oil supplements is about half the amount in a single serving of salmon. So it’s difficult to interpret these results in relation to people taking omega-3 supplements, because their blood levels may be lower than those in the study’s prostate cancer group.
Personally, I still support taking 1,000-2,000 milligrams of omega-3s daily for overall health. And I support taking about 2,000-4,000 milligrams of omega-3s daily as one option for lowering bad cholesterol and triglycerides, and raising good cholesterol.
Regarding prostate cancer, you can be tested for this using a blood test called a PSA, along with a rectal exam. The American Urological Association recently noted that the PSA test is not recommended for patients under age 55 and over age 80, but for men aged 55 to 69, it may be a helpful tool for prostate-risk assessment.
Talk to your doctor. While these tests aren’t perfect, they may help you understand if you have underlying prostate problems, and may influence whether you choose to take omega-3s.