Are fish oil and omega-3s the same thing? —H.B., Hastings-on-Hudson, N.Y.

No. Fish oil is an especially rich source of omega-3 fatty acids, which are also found in flaxseed, walnuts, and dark leafy greens. Research has shown that certain omega-3s reduce the risk of a second heart attack and lower heart-attack risk in healthy people. But fish oil contains other fatty acids and fats, too. So when choosing a supplement, look at the amount of omega-3s—not the total amount of fish oil—in each pill to determine what dose to take. With most fish-oil pills, you’ll need several capsules a day to get the 1-gram daily dose recommended for people with heart disease, CONSUMER REPORTS tests have found. (People without heart disease need only about 2 grams of omega-3s per week, an amount you can usually reach by eating several servings of omega-3-rich foods, particularly fatty fish such as salmon, trout, and whitefish.)

For more information, read about the benefits of fish oil and a heart-healthy diet (free), and take a look at our Natural Medicine Ratintgs. (subscribers only).

This article first appeared in the April 2008 issue of Consumer Reports On Health.