Omega-3s Protect the Heart from Mercury in Fish
Omega-3: Fish Oil Protects the Heart from Mercury in Fish
The consumption of fish can increase the intake of mercury, which is harmful to the heart, but marine-derived Omega-3 counteract the effects of this metal. Mercury accumulation in the body increases the risk of heart attack, but high concentrations of Omega-3 present in fish protect the cardiovascular system from the harmful effects of this health threat. This discovery comes from Umeå University (Sweden), where a group of scientists led by researcher Maria Wennberg sought to clarify the risks associated with exposure to this metal, which can be abundant in the same fish from which the body obtains Omega-3. Their study results were published in the American Journal of Clinical Nutrition1.
Risks and Benefits of a Fish-Rich Diet
Since the 1970s, when researchers discovered the cardiovascular benefits associated with Omega-3 consumption, experts have recommended eating foods rich in these nutrients to protect heart health. Among these, fatty fish such as tuna, herrings, salmon, and mackerel stand out. However, high consumption of this type of fish increases the risk of mercury intake, a metal dangerous for health. In general, heavy metals are toxic to the nervous system, especially that of fetuses and children. Moreover, past studies have linked mercury exposure from fish to an increased risk of heart attack. This connection has also been confirmed by the research of Wennberg and colleagues.
A Harmful Effect Countered by Omega-3
The study’s authors analyzed mercury levels in the blood and hair of more than 1,600 men in Sweden and Finland. Among them, 572 had suffered a myocardial infarction. Combining these analysis results with data on participants’ health and lifestyle revealed that just 3 micrograms of mercury accumulated per gram of hair increases the risk of heart attack. However, this association holds only for those with low Omega-3 levels in the body. Indeed, the mercury levels needed to increase heart risks are higher if high amounts of Omega-3 are also present. In other words, mercury and Omega-3 influence the risk of heart attack in opposite ways.
Protecting Against 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, specifying that the best choice to avoid excessive mercury intake is to prefer non-predatory fatty fish (such as salmon). Indeed, fish that are at the top of the food chain, like 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-3 can be taken in the form of mercury-purified fish oil. In this case, the heart risks would be eliminated while the benefits 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]
