On the one hand, fish is a low-fat, high-protein food that fits perfectly into a healthy diet—and should be enjoyed at least twice a week. Even fatty fish, such as salmon, contain heart-healthy omega-3 fatty acids, which, among other things, help boost artery-clearing HDL cholesterol and reduce inflammation. Yet we are also told that eating fish can expose us to dangerous contaminants such as mercury, and chemicals such as PCBs. So is fish good or bad for us?

A new report by the Institute of Medicine, which advises the government on health policy, tries to help sort through the confusion. It concludes that eating fish twice a week is indeed good for us—that the potential cardiovascular benefits outweigh the risks of exposure to contaminants, and that government agencies should do a better job of promoting this message.

But despite this endorsement, researchers at the institute are unclear how eating fish fights heart disease. It may be the omega-3 fatty acids, or simply eating lean fish in place of high-fat, high-cholesterol meats. Yet they are convinced that fish-based omega-3s offer neurological benefits to babies, and help mothers carry their babies to term.

As a result, the institute states that pregnant women can consume up to 12 ounces of fish a week (including up to six ounces of albacore tuna), and should avoid fish such as shark, tilefish, king mackerel and swordfish. Surprisingly, these general guidelines also apply to children under 12. For everyone else, including those at risk of heart disease, the institute advises that if we eat more than two servings of seafood a week, we should eat a variety of fish to reduce our risk of exposure to contaminants.

The Institute of Medicine's report doesn’t provide a list of good and bad fish. Its purpose was simply to assess the risks and benefits of eating fish so government agencies can present a clearer message to consumers. In the meantime, we’ll still debate whether it’s ok to eat farmed salmon, and, in our house, whether fish sticks count as a serving of fish!

More on Eating Fish

• Good Fish, Bad Fish by About’s Guide to Nutrition
• American Heart Association on Fish, Fish Oils and Heart Health
• EPA on What You Need to Know About Mercury in Fish and Shellfish
• FDA’s List of Mercury Levels in Fish
• Oceans Alive’s Best and Worst Seafood Choices
• Low Fat Fish and Seafood Recipes

_{Photo © 2006 Fiona Haynes, licensed to About.com, Inc.}