Everyone knows fish is good for you. It's low in saturated fat, and it makes you smart. So it's no wonder consumers are confused by headlines warning fish eaters of impending doom.

In late 2002, a San Francisco Chronicle headline warned that eating fish can be risky because of the high content of mercury in some deep-water fish. A physician in Northern California had discovered that wealthy individuals eating expensive fish, such as swordfish and tuna, were putting themselves at risk for mercury poisoning -- even as they were trying to eat healthy.

In one case, a woman suffered hair loss and high levels of mercury in her blood. That spurred Dr. Jane M. Hightower, an expert of internal medicine at San Francisco's California Pacific Medical Center, to fish around for answers.

Hightower studied her own patients, who were affluent and ate plenty of gourmet fish -- swordfish, sea bass, halibut and ahi tuna. She found that patients who often ate these fish or were experiencing symptoms of mercury exposure (fatigue, headache, joint pain, and reduced memory and concentration) had unacceptable levels of mercury in their blood.

Hightower retested these patients after they abstained from the suspect fish for six months. The high levels of mercury disappeared. Not surprising, the FDA has issued warnings about high levels of mercury for some of these fish.

Fish remains tasty - and healthy

Fish is naturally low in cholesterol and has been the protein of choice for cardiologists and weight-conscious Americans. It is a fantastic source of omega-3 fatty acids, which have been shown to lower the risk of heart disease by lowering cholesterol and decreasing the stickiness of blood platelets. This means omega-3 fats can lower the risk for stroke.

Studies have shown conclusively that men and women who eat a diet rich in fatty fish -- salmon, mackerel, sardines, anchovies and tuna -- are less likely to suffer heart disease and stroke. One study published in the journal Circulation (American Heart Association) showed that eating fish regularly reduced the risk of heart disease in diabetic women as much as 64 percent.

Researchers at Chicago's Rush-Presbyterian-St. Luke's Medical Center found that older people who eat fish at least once a week may cut their risk of Alzheimer's disease by more than half.

It's not necessary to eat fish every day to reap the benefits. According to a study in The Journal of the American Medical Association, men who ate about three to five ounces of fish one to three times a month were 43 percent less likely to have a stroke during 12 years of follow-up. Men who ate fish more often did not reduce their risk any further.