Michael Hawthorne and Sam Roe of the Chicago Tribune report that the United States safety net for safeguarding consumers against the increased mercury levels in fish is in tatters. In the article the reporters detail the fate of one particular piece of fish:
When a fillet from that fish reached a display case at a supermarket in suburban Des Plaines, it carried no government warning labels, even though federal officials know swordfish often is so contaminated that young children and pregnant women should never eat it.
The Chicago Tribune actually bought and tested a portion of this fish, which produced alarming results:
In some cases, regulators have ignored the advice of their own scientists who concluded that mercury was far more dangerous than what consumers were being told.
In other instances, regulators have made decisions that benefited the fishing industry at the expense of public health.
However, the best way to prevent a heart attack or stroke is to follow a high-nutrient diet with little or no animal products, thereby ensuring that such blockages don't develop in the first place. Then eating fish won't matter. In fact, the reason fish-derived fats, EPA and DHA, are not considered essential fats is that almost all people have enzymes to convert the plant-derived omega-3 fat rapidly into EPA and DHA.1
Fish is a double-edged sword, especially because fish has been shown to increase heart attack risk if polluted with mercury.2 It seems that the cardioprotective effects of eating a little fish is lost when you eat lots of fish, most likely because lots of fish exposes you to high mercury levels, which can promote lipid peroxidation.3 Lipid peroxidation plays a major role in the development of diseases such as heart disease, diabetes, and arthritis.
Fish with Highest and Lowest Mercury Levels
- white snapper
Source: Mercury levels in seafood species. U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition. Office of Seafood, May 2001.
The bottom line: Choose fish over other animal products, but be aware that the place where it was caught, and the type of fish, matters. Don't accept recreational fish from questionable waters. Farmed fish is safer. Never eat high-mercury-content fish. Don't eat fish more than twice a week, and if you have a family history of hemorrhagic stroke, limit it further to only once a month.
1. Siguel, E.N., and M. Macture. 1987. Relative enzyme activity of unsaturated fatty acid metabolic pathways in humans. Metabolism 36: 664-69
2. Salonen, J. T., K. Seppanen, K. Nyyssonen, et al. 1995. Intake of mercury from fish, lipid peroxidation, and the risk of myocardial infarcation and coronary, cardiovascular, and any death in eastern Finnish men. Circulation 91: 645-55.
3. Salonen, op. cit.
4. Shamlaye, C. F., D. O. Marsh, G. J. Myers, et al. 1995. The Seychelles Child Development Study on neurodevelopmental outcomes in children following in utero exposure to methylmercury from a maternal fish diet: background and demographics. Neurotoxicology 16 (4): 597-612; Rylander L., U. Stromberg, and L. Hagmar. 1996. Dietary intake of fish contaminated with persistent organochlorine compounds in relation to low birthweight. Scand. J. Work Environ. Health 2 (4): 260-66; Does methylmercury have a role in causing developmental disabilities in children? 2000. Environ. Health Perspect. 108 (supp.3): 413-20.
5. Clarkson, T.W. 1997. The toxicology of mercury. Crit. Rev. Clin. Lab. Sci. 34(4):369-403.