Harvard Health Letter

By the way, doctor: How much fish oil should I be taking?

Q. What's the right daily dose of omega-3s? I have a bottle of 1,000-mg fish-oil pills. Is one a day enough to get the benefit?

A. The two main omega-3 fats found in fish are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Omega-3 fats, and perhaps especially EPA and DHA, have a variety of health benefits, but many people don't like the taste of fish or worry that it may contain toxins such as mercury. Fish-oil capsules are a way to get omega-3 fatty acids without having to eat fish. The capsules, while large and a bit hard to swallow, keep the fish oil well contained so you don't have to taste it, although some people still notice a fishy aftertaste.

Studies have shown fish-oil capsules do seem to have cardiovascular benefits, including lowering blood pressure and reducing triglyceride levels. There's evidence, too, that capsules lower the overall risk for fatal heart attack (as does eating fish regularly). The results aren't all positive; for example, a study of people prone to sudden death from heart-rhythm abnormalities found that fish-oil capsules did nothing to reduce this risk.

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