Omega-3s and prostate cancer

Published: Tuesday, August 20, 2013 at 6:01 a.m.
Last Modified: Monday, August 19, 2013 at 3:47 p.m.

Q: I hear that taking an omega-3 supplement and eating salmon increases my risk for prostate cancer. That doesn't sound right. What's the deal?

— Greg S., Houston

A: Those fishy reports from a new study didn't pass the smell test, did they? We'll explain.

The study: The research you're referring to looked at men's blood plasma levels of omega-3s and found that those with the highest levels had a 43 percent to 71 percent increased risk of prostate cancer. That sounds pretty startling.

But, the blood test they used reveals only recent consumption of omega-3-rich foods or supplements. Researchers didn't know which guys in the study recently had eaten fish or taken a supplement! Plus, other studies make us think that guys who are diagnosed with prostate cancer may increase their intake of omega-3s (lots of prior data show it's beneficial). So high levels may be from guys getting diagnosed with prostate cancer, not the other way around. And besides, no one in the study (with or without prostate cancer) had very high levels of omega-3s!

One more thing: The Japanese eat far more fish (salmon and ocean trout may have more to recommend them than just their omega-3s), consuming more fatty acids than North Americans. Plus, they have a lower risk for prostate cancer.

What we know about omega-3 benefits: A diet high in walnuts (a very potent source of omega-3s) seems to inhibit the growth of prostate cancer, according to a new study in mice. And omega-3s may inhibit growth of breast cancer. In our humble opinions, there's a lot of research to indicate that DHA omega-3 helps protect you from diabetes; decreases joint pain and inflammation; helps prevent dry macular degeneration; and makes your brain function as if it were six years younger! So, we believe the benefits for men and women far outweigh the risks, and suggest you take 900 mg of algal DHA omega-3 a day, like we do.

Email your health and wellness questions to Dr. Oz and Dr. Roizen at youdocsdaily@sharecare.com.

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