Fish contain high levels of omega-3 fatty acids, compounds that provide numerous health benefits such as reducing cholesterol and blood pressure. Although eating fish is one way to consume omega-3 fatty acids, concerns about mercury poisoning may limit the amount of fish you can safely eat. Fish oil supplements, such as salmon oil, are one alternative source of omega-3 fatty acids that typically contain lower levels of contaminants than whole fish.
Purified Supplements
Most commercially available fish oil supplements, including salmon oil supplements, are purified during the production process to remove mercury and other toxins. Carefully read the label of any salmon oil supplement before you buy it and check to make sure it is purified to remove toxins. You can also look for certifications, such as the International Fish Oil Standards certification, which tests fish oil supplements for levels of toxins such as mercury.
Mercury Levels
Testing of commercially available fish oil supplements usually reveals very low or undetectable levels of mercury, according to a study published in the December 2003 issue of the journal "Archives of Pathology & Laboratory Medicine." Of five brands tested, three had undetectable levels, and two contained trace amounts of mercury. The brands with undetectable levels were Kirkland, Nordic Ultimate and Sundown, and the brands with trace levels were CVS and Omega Brite.
Mercury Levels in Fish
The levels of mercury in fish depend on the position of the particular species of fish in the food chain. Larger fish that are higher on the food chain, such as shark, swordfish, tilefish and mackerel, tend to have higher levels of mercury and other toxins because eating smaller fish causes the larger fish to ingest all of the toxins in the smaller fish, explains the University of Maryland Medical Center. Smaller fish, such as salmon, cod and herring, tend to have lower levels of mercury.
Other Toxins
Besides mercury, fish may contain other toxins, including dioxins and polychlorinated biphenyls, or PCBs. The purification process used to make salmon and fish oil supplements also removes these toxins. Again, carefully check the label of fish oil supplements to make sure they are purified.
References
- "Archives of Pathology & Laboratory Medicine"; Measurement of Mercury Levels in Concentrated Over-the-Counter Fish Oil Preparations: is Fish Oil Healthier than Fish?; Stacey E. Foran et al., December 2003
- University of Maryland Medical Center: Docosahexaenoic Acid (DHA)
- "The New York Times"; The Claim: Fish Oil Supplements Can Contain Mercury; Anahad O'Connor; March 2009
Member Comments