Mercury in fish linked to risk of heart disease

Certain species of fish contain levels of mercury linked with an increased risk of heart attack, a study indicates.

Certain species of fish contain levels of mercury linked with an increased risk of heart attack, a study indicates.

Mercury is a toxic chemical that pollutes the seas and is absorbed naturally by fish. Fish with the highest mercury levels include swordfish, king mackerel, shark and tuna.

An international team of scientistscompared the levels of mercury in toenail clippings taken from 684 men who had had heart attacks with 724 men who were healthy. They also compared the levels of docosahexaenoic acid (DHA) in their fatty tissue, which is the constituent of fish known to cut the risk of heart attack. The study showed that the men with the highest mercury levels who ate the most fish were at twice the risk of suffering a heart attack than those with average levels.

The mercury wiped out the beneficial effect of the DHA. The authors of the study, published in the New England Journal of Medicine, said: "High mercury content may diminish the cardioprotective effect of fish intake."

The British Heart Foundation said people should still eat fish twice a weekfor their omega-3 oils.