Q. I've heard that fish contains oils that are good for your health. Does this mean I should take a fish oil supplement?
A. You heard right. A good deal of evidence suggests that fish oils are good for your health. I wish I could say, "So just eat fish and take fish oil capsules, and your health will be great." But of course it's not that simple.
Fish oils are rich in omega-3 fatty acids, a kind of "healthy fat." People with diets rich in omega-3 fatty acids seem to have a decreased risk of heart disease and stroke.
The protective effect of omega-3 fatty acids may stem from several different effects they have on the body. They keep platelets from forming clots in the blood. They help reduce blood pressure. They raise HDL, the so-called "good cholesterol." They lower levels of another kind of fat linked to heart disease and strokes: triglycerides. Probably most important, they seem to prevent lethal heart-rhythm disorders from developing.
But you asked specifically about fish oil supplements. If you told me you loved to eat fish, I'd tell you to keep doing that. The evidence that fish oils are heart-healthy comes mainly from studies of eating fish, not from swallowing fish oil capsules. The evidence that eating fish is heart-healthy and brain-healthy is very strong.
Perhaps you don't like to eat fish but are concerned about heart disease. Although the evidence of benefit from fish oil capsules is not as strong as with eating fish, it's still pretty strong. In my opinion, it's strongest in showing a protective effect against dangerous heart rhythms that can lead to cardiac arrest. In addition, I'd say there is no risk in taking a daily fish oil supplement.
Typical over-the-counter fish oil supplements contain eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA), the omega-3s found in fish. Many authorities recommend that if you already have heart disease or high levels of triglycerides, you should discuss with your doctor taking 3,000 milligrams of fish oil capsules per day. If you have elevated triglycerides, your doctor may recommend a higher dose (or some other treatment to lower triglycerides).
We have more information on good fats in our Special Health Report, "Healthy Eating." (Learn more about this report at AskDoctorK.com, or call 877-649-9457 toll-free to order it.)
As beneficial as fish oil capsules may be, I prefer to get nutrients from foods rather than supplements. That's because whole foods often have other nutrients that may also be good for your health. Fatty fish such as salmon, mackerel, herring and sardines are especially good food sources of omega-3s. I eat fish at least once or twice a week -- but that's not hard because I love fish!
• Dr. Komaroff is a physician and professor at Harvard Medical School. Go to his website to send questions and get additional information: AskDoctorK.com.