By Shelly DeButts

fishWhat can fish do for you? Help your heart? Lower cholesterol? Prevent cancer? It turns out the answer may be all of the above—and more.

Health professionals have long recognized the heart-health benefits of consuming omega-3 fatty acids, which are found in abundance in certain coldwater fish such as salmon, herring, mackerel, sardines, and albacore tuna. Now there is mounting evidence that getting enough omega-3 fatty acids in your diet may help with a host of ailments, from arthritis to Alzheimer's disease and cancer.

Although the exact mechanisms that produce these benefits are still poorly understood, nutrition scientist Jamy Ard, M.D., medical direc­tor of UAB's EatRight Weight Management Services, says the anti-inflammatory powers of omega-3 fatty acids are the reason for their effec­tiveness. "Inflammation plays a pivotal role in many diseases," he says. "And omega-3 fatty acids quite simply help reduce inflammation."

Ard notes that eating seafood offers another important health benefit—fish generally replace less-healthy meats in the diet, such as calorie-laden steaks and cholesterol-choked hamburgers. "You get something good," he says, "and you give up something bad at the same time. It's a two-for-one deal."

For a generally healthy person, eating a variety of coldwater fish two or three times a week is enough to maintain a beneficial level of omega-3s, says Ard. There has been concern that the same species of fish that contain these beneficial ingredients also can have toxic concentrations of mercury. But Ard says that eating three servings or less per week should be safe, although pregnant women should consult a physician to determine if their risk of mercury contamination is greater than the potential health benefits.

Fish are not the only way to fit omega-3s into your diet. Tofu, soybeans, flaxseed, flaxseed oil, and canola oil contain alpha-linolenic acid, which the body can convert into omega-3 fatty acid. Ard notes that people with existing cardiovascular disease or other problems should talk to their doctors about methods of getting more omega-3s into their systems. But for most of us, eating more fish can be the best way to make a step toward a better diet—and it doesn't have to be expensive, Ard points out. Lake trout is on the list of beneficial species and it is nowhere near as pricey at the local grocery store as the seared tuna entree at a high-end restaurant.

Not all fish are created equal, however. The fried sandwich at your favorite fast-food restaurant probably doesn't include the coldwater variety of fish that contain omega-3s. And the preparation process piles on additional fat grams and calorie density. If your goal is to help your heart by adding omega-3s to your diet, this is not the way to do it, says Ard. "Those sandwiches taste good," he admits. "But they're probably the worst thing for you on the menu."