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Fish Oils decrease the risk of heart attack but methylmercury in some fish raises the risk; eat fish low in mercury

Oct 11, 2012

Fish Oils decrease the risk of heart attack but methylmercury in some fish raises the risk; eat fish low in mercury

     The methylmercury found as a contaminant in some fish has been tied to an increased risk of heart attack in some studies. On the other hand the EPA and DHA fats found in some fish are regarded as beneficial. Researchers from Sweden and Finland examined the relationship of how exposure to fish oils and methylmercury relates to heart attack risk.
The researchers compared the level of mercury in the hair to the level of fish oils in the blood of 572 men who suffered with heart attacks. Hair mercury was associated with a higher heart attack risk and blood levels of fish oils were associated with a lower risk of heart attack. Even a small increase in fish oil intake of 1% would prevent 7% of future heart attacks despite a small increase in mercury exposure. However at a high hair mercury content the protective effects of fish oils against heart attack was counteracted.
The conclusion is that higher methylmercury intake is related to an increased risk of heart attack and higher fish oil intake is associated with a lowered risk of heart attack. Therefore eat fish high in fish oils and low in methylmercury. The study is published in the October 2012 issue of the American Journal of Clinical Nutrition

Note; the major source of methylmercury exposure is to the burning of fossil fuels by coal burning utilities and through the consumption of fish. Large predatory fish consume smaller fish and accumulate the mercury stored in these smaller fish and some game fish have been found to have methylmercury levels exceeding 1,000,000 that of the surrounding waters. Methylmercury is lower in salmon, cod, flounder, rainbow trout, tilapia, haddock, herring, sardines and anchovies; eat these for fish oils. Methylmercury is higher in shark, swordfish, marlin, king mackerel, tilefish, and larger species of tuna, walleye, and large mouth bass.