Fish oil supplements contain oil from the fatty tissues of fish. Because contaminants in the ocean also accumulate in the fatty tissues, you may worry about the potential for contamination with methylmercury or polychlorinated biphenyls, also called PCBs, in fish oil supplements. Commercial fish oil supplements undergo purification to remove contaminants in one of several ways. Most methods produce adequately purified and safe products, according to the Environmental Defense Fund.
Molecular Distillation
Molecular distillation is the most effective method for reducing contaminants in fish oil to far below acceptable industry standards, according to Bioriginal Food & Science Corporation, a Canadian company that produces fish oil supplements. Molecular distillation concentrates the omega-3 fatty acids in the fish oil, creating supplements with more omega-3 fatty acids than the original product. This process separates the fatty acids from their original triglyceride form and converts them into ethyl esters, which may have less bioavailability and are also less stable and oxidize more readily than triglycerides, Ascenta Health reports.
Oil Refining
Oil refining does not concentrate the amount of omega-3 fatty acids in the oil and removes fewer contaminants, although the amounts still fall below acceptable industry standards, the Bioriginal Food & Science Corporation explains. Because higher temperatures are used to purify the product, increased oxidative damage could occur. On the other hand, this method preserves the original triglyceride form of the oil rather than turning it into ethyl esters. The amounts of omega-3 fatty acids cannot be increased or changed using this method.
Steam Distillation
Steam distillation uses steam and vacuum techniques to remove impurities. Steam distillation, a less-expensive method of purification than molecular distillation, does not allow for concentration of fish oils and uses high heat to purify the product.
Considerations
Manufacturers may use a combination of different distilling techniques, sometimes referring to their product as "pharmaceutical grade" even though this term does not mean a fish oil has additional benefits or purification, chiropractor David Seaman, M.S., explains in the January 2010 issue of "Dynamic Chiropractic." Pharmaceutical grade refers to the size and uniformity of the particle size used to make a product, according to Seaman. While the State of California, the U.S. Environmental Protection Agency, the U.S. Food and Drug Administration the Canadian Food Inspection Agency, and the European Union all set standards for evaluating contaminants in fish oil, the FDA has the least stringent standards.
References
- Environmental Defense Fund: How Safe Are Fish Oil Supplements?; February 2011
- "Dynamic Chiropractic"; Pharmaceutical Grade vs. Pharmaceutical Made; David Seaman, D.C.; January 2010 (PDF)
- Bioriginal Food and Science Corporation: Molecular Distillation or Oil Refining? The Facts on Fish Oil
- Ascenta Health: Fish Oil Triglycerides vs. Ethyl Esters: A Comparative Review of Absorption, Stability and Safety Concerns
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