Omega-3s protect the heart from mercury in fish
Omega-3: fish oil defends the heart from mercury in fish
Fish consumption can increase intake of heart-damaging mercury, but marine-derived Omega-3s counteract the effects of this metal.Mercury accumulation in the body increases the risk of heart attack, but high concentrations of the Omega-3s found in fish protect the cardiovascular system from the damaging effects of this health enemy. The discovery comes from Umeå University (Sweden), where a group of scientists led by researcher Maria Wennberg set out to clarify the risks associated with exposure to this metal, which may be found in the same fish from which the body obtains Omega-3s. The results of their studies were published in the American Journal of Clinical Nutrition1.
Risks and benefits of eating a diet rich in fish
Ever since researchers discovered the cardiovascular benefits associated with Omega-3 consumption in the 1970s, experts have recommended the consumption of foods rich in these nutrients to protect cardiovascular health. Prominent among these are fatty fish such as tuna, herring, salmon and mackerel. High consumption of such fish, however, increases the risk of consuming mercury, a metal that is hazardous to health. In general, heavy metals are toxic to the nervous system, especially that of the fetus and children. Not only that, studies have previously associated exposure to mercury in fish with an increased risk of heart attack. The existence of this link has also been confirmed by the research of Wennberg and colleagues.
A harmful effect counteracted by omega-3s
The study authors analyzed mercury levels in the blood and hair of more than 1,600 men in Sweden and Finland. Among them, 572 had experienced a myocardial infarction. Combining the results of these analyses with data regarding the participants' health and lifestyle, it was found that as little as 3 micrograms of mercury accumulated in 1 gram of hair increased the risk of heart attack. However, this association only applies to those with low levels of Omega-3 in the body. In fact, the levels of mercury needed to increase the risks taken by the heart are higher if high amounts of Omega-3 are also present. In other words, mercury and Omega-3 affect inopposite ways the likelihood of having a heart attack.
Protect yourself from mercury with fish
According to the researchers, these results suggest that the risk of heart attack can be reduced by increasing consumption of fish rich in Omega-3, but low in mercury. Wennberg reiterated the need to eat fish 2-3 times a week, pointing out, however, that the best choice to avoid taking in too much mercury is to prefer non-predator fatty fish (such as salmon). In fact, fish that are at the top of the food chain, such as king mackerel, can accumulate much more mercury than other species. For this reason, they should not be eaten more than once a week. Alternatively, Omega-3s can be taken in the form of mercury-purified fish oil. In this case, the risks to the heart would be eliminated, while the benefits would remain intact.
Source:
1. Wennberg M, Strömberg U, Bergdahl IA, Jansson JH, Kauhanen J, Norberg M, Salonen JT, Skerfving S, Tuomainen TP, Vessby B, Virtanen JK, "Myocardial infarction in relation to mercury and fatty acids from fish: a risk-benefit analysis based on pooled Finnish and Swedish data in men," Am J Clin Nutr. 2012 Aug 15. [Epub ahead of print].
