Study indicates that high mercury in fish overrides health benefits by omega 3s .  By David McGuire, Got Mercury

A new study indicates that Omega-3 fatty acids and mercury, both found in fish, appear to have opposing  affects on cardiac health and risk of myocardial infarction.

This study published in the American Journal of Clinical Nutrition, looked at data from more than 1,600 men from Sweden and Finland.  Men with high levels of mercury in their body had an increased risk of heart attacks, while those with a high concentration of omega-3s had a lower risk.

Predatory fish such as shark, swordfish, kind mackerel and tilefish are at the top of the marine food chain and for that reason concentrate mercury from the environment in their tissues. Methyl mercury is known to be toxic to the nervous system, especially in fetuses and children. The US Federal Drug Administration and the U.S. Environmental Protection Agency warns women of childbearing age and children against eating predatory fish and that men and women outside the ages minimize their consumption of high mercury fish.

The men in the study submitted hair and blood samples to measure their mercury and omega-3 levels, as well as information on their health and lifestyle.

The average mercury level among the Swedish men was 0.57 micrograms per gram of hair, and more than twice as high in their Finnish peers. Swedes also had higher levels of omega-3s than did Finns.

The study reports found that men with at least 3 micrograms of mercury per gram of hair had an increased risk of heart attacks compared with men with 1 microgram per gram only of the subjects also had low levels of omega-3 fats. For men with higher Omega-3s, it took higher levels of mercury to see an increased heart attack risk, suggesting the two compounds might have opposite effects on cardiac health.

Got mercury has found that other fish such as tuna have high levels of mercury, and that the levels vary between where the fish was caught and what type of tuna. In general, smaller fish that do not accumulate mercury have the benefits of Omega-3s without the risk of mercury.

Full study here http://ajcn.nutrition.org/content/early/2012/08/15/ajcn.111.033795.abstract?sid=76865977-6cc0-474c-b07f-e496eb4dc834