Fish oil has proven benefits in lowering cholesterol levels, which can decrease the risk of heart disease. Many people take daily supplements of over-the-counter fish oil products or prescription-dose fish oil capsules; sales of fish oil products exceeded $190 million in 2003, the Environmental Defense Fund, or EDF, reports. But it's a well-known fact that many of the ocean and lake fish are contaminated with chemicals used in industry, such as methylmercury, dioxin or polychlorinated biphenyls, more commonly known as PCBs. Concerns over the safety of fish oil have been raised.
Limits
In fish oil supplements, PCBs are a greater concern than mercury, which accumulates mostly in the fish meat rather than the oil. Because PCBs are known cancer-causing agents, government agencies set limits on the allowed amounts in fish oil. But different agencies set different standards. The U.S. Food and Drug Administration sets the limit at 2,000 parts per billion, while the California sets the limit at 90 ppb, according to the EDF.
Testing
In 2010, the Mateel Environmental Justice Foundation filed a lawsuit against manufacturers whose products exceeded the limits in independent tests. Of the 10 products tested, three contained PCB levels above the California standard, with wide variation between manufacturers. The Environmental Defense Fund surveyed fish oil manufacturers about their purifying methods and standards for acceptable levels. They found that 80 percent of the 75 manufacturers they surveyed used acceptable processes for removing contaminants. Of the rest, 21 did not provide complete answers. Seven did not respond.
Methods
Contaminants can be removed from fish oil by molecular distillation and steam deodorization. These methods remove impurities through the combined action of pressure and high heat. These treatments can lower the amount of PCBs in fish oil supplements to half that found in fish, according to a 1998 study published in "Chemosphere." Manufacturers that follow standard safety procedures for contaminant removal often label their products accordingly.
Alternatives
The omega-3 fatty acids found in fish are considered essential, meaning that the body can't make them, so they must come from food sources. Since the omega-3 fatty acids in fish oil have many known benefits, people with heart disease should take prescription forms of fish oil, which undergo more rigorous testing, according to University of California San Francisco cardiologist Gordon Fung, a spokesman for the American Heart Association. People without cardiac risks should stick with fresh fish, Fung also recommends. However, Jeffrey Ashley, an environmental biochemist at Philadelphia University, states that his research has found lower levels of PCBs in fish oil compared to fish portions, taking into the account the amount of fish you would need to consume to get the same amount of oil.
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