The benefits of eating oily fish may counteract any dangers attributed to increased exposure to harmful toxins, according to new research published in the American Journal of Clinical Nutrition.
Although many experts recommend people up their intake of omega-3 rich seafood to boost their heart health, several species of oily fish are also associated with containing high levels of mercury, which has been linked with heart problems, leading to warnings to regulate consumption.
Scientists studied more than 900 Swedish men and women who filled out a survey about their dietary habits. The researchers then analyzed the subjects' red blood cells to measure levels of mercury.
The research team found that mercury levels in the subjects were low by Scandinavian standards but still higher than much of the U.S. population. However, the people whose red blood cells showed elevated amounts of mercury did not have a higher risk of cardiac problems than those whose red cells contained less
Maria Wennberg, a public health researcher at Ume University and a member of the study team, told Reuters Health the results suggested "the protective nutrients in fish override any harmful effect of mercury at these low levels of mercury."
However, she added that the study did not "discard the need of restrictions in consumption of fish high in mercury."
Fish concentrate mercury in their fatty tissues in a process known as biomagnification. Much of the excess mercury in watersheds and the oceans comes from deposition from the smokestacks of coal burning power plants. Many governments advise women who are pregnant or who might become pregnant to avoid the eating the flesh of long-lived, apex predators such as shark, swordfish, king mackerel or tilefish because of their high mercury content. Lake trout, it should be noted, could also be added to the list but the fish is rarely consumed any more after the collapse of the fisheries in the U.S. Great Lakes.