Fish safety, mercury and PCBs

In recent months we have all heard a lot about fish safety concerns. The issue is confusing, because while there are studies that show hazards, other studies continue to identify health benefits associated with eating fish. What should we do?

In one study, 48 cans of tuna bought at large chain stores, including Whole Foods, were analyzed for mercury content. 16 were found to contain twice or more the amount of mercury considered “safe” by the FDA. (Nutrition Week, June 30, 2003;31(13):6, see also

You may wonder how significant this really is to your health. According to the Agency for Toxic Substances and Disease Registry of the U.S. Department of Health and Human Services, mercury is the most toxic substance in the United States, and is the third most frequently found after lead and arsenic (see

Another report from the July 30, 2003 edition of The New York Times indicates that farm-raised salmon – which includes all the Atlantic salmon in stores – is high in PCBs, highly toxic chemical wastes. PCBs have been shown to cause cancer at very low concentrations and also have detrimental effects on the nervous system, affecting memory, focus, and ability to learn. For more information on the effects of PCBs on health, visit

Some nutrition experts have concluded that, to ensure our safety, we should eliminate all fish from our diet. I disagree, because this position implies that other foods are pristine and that just replacing fish with something else will benefit our health. Unfortunately this is far from true. We need to become well-informed shoppers because fish, when carefully chosen, can be health-enhancing.

Other studies continue to show benefits, including lower cancer rates in people who regularly consume fish. This seems very confusing, but it makes sense when you realize that fish is a rich source of protein (amino acids) that help strengthen the immune system and provide tools our bodies need to cope with environmental toxins – ironic, but true. An example of this is the dietary supplement Seacure, which is made from predigested fish protein. Independent studies have shown that Seacure can help people with irritable bowel syndrome and other conditions. The Pacific whitefish supply used to make Seacure is tested regularly and found to be free of contaminants. You can read about Seacure at

The solution to this dilemma is to select the fish we eat very carefully. There are types of fish that are relatively uncontaminated, enabling us to draw the benefits from this valuable food source while avoiding unnecessary and potentially dangerous exposure to toxins. Possibly the best choice is true wild Alaskan salmon. To be sure you get the cleanest, order it from, a group that closely monitors the quality of their products, or other reliable sources. In general, I recommend avoiding large predator fish, including swordfish and tuna, bottom feeders (including flounder) and all farm-raised fish. The cleanest fish might well be those from the Pacific Northwest.

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