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Some popular fish oil supplements may be a little fishy when it comes to quality.

A new test of 15 top-selling fish oil supplements by Consumer Reports shows five fell a bit short on quality.

The good news is all 15 of the fish oil supplements evaluated by an independent lab contained their labeled amount of EPA and DHA, omega-3 fatty acids that have been shown to reduce the risk of heart attacks and stroke.

But four of the fish oil supplements tested contained trace levels of polychlorinated biphenyls (PCBs).

“In our recent tests, we found that some were not as pure as one might think,” Ronni Sandroff, editorial director of Health and Family at Consumer Reports, said in a news release.


Another supplement’s coating failed to meet U.S. Pharmacopeia (USP, a non-government pharmaceutical standards-setting organization) standards for disintegration.

PCBs In Fish Oil Supplements

None of the fish oil supplements contained contaminants, such as lead, mercury, or PCBs, that exceeded levels set by USP or the European Union. However, four of the fish oil supplements contained total PCBs in levels that would require warning labels under California’s Proposition 65, a consumer right-to-know law.

PCBs are part of a group of man-made organic chemicals that were widely used in industry until they were banned in 1979 after they were linked to cancer. Although no longer in use, the chemicals accumulate in the environment and are sometimes found in fish and plants that have been exposed to contaminated water or soil.

Researchers say most of the tested fish oil supplements claimed to be “purified” or “free” of PCBs and other contaminants. But those claims have no specific regulatory definition, according to the FDA. Dietary supplement companies base these claims on self-regulatory or European standards. For example, the USP limit on PCBs is 2 parts per trillion per gram.

The report does not say what levels of PCBs were found in the fish oil supplements. Researchers say the total PCB amounts in four brands (CVS Natural, GNC Triple Organic, Nature’s Bounty Odorless, and Sundown Naturals) were below the USP safe limit but within the range that would require a warning label under California’s Proposition 65, 90 parts per billion.

Putting Fish Oil Supplements To The Test

For the report, the consumer agency purchased three lots of 15 different top-selling brands of fish oil supplements online and in the New York metropolitan area.

The samples were sent to a lab where they were tested for contaminants as well as spoilage and whether they disintegrated properly.

Two of the three samples of Kirkland Signature Enteric 1200 fish oil supplements had an enteric coating (designed to prevent a fishy aftertaste) that did not disintegrate properly. The coating may break up in the stomach rather than in the small intestine, as desired for proper absorption by the body.

Nine brands passed all quality measures tested, including:

  • Spring Valley Omega-3
  • Finest Natural
  • Walgreens Omega-3 Concentrate
  • Barlean’s Organic Oils EPA-DHA
  • Nature Made 1,200 MG
  • The Vitamin Shoppe Meg-3 EPA-DHA
  • Carlson Super Omega-3 Gems
  • Norwegian Gold Ultimate Critical Omega
  • Nature’s Way Fisol

One product, Nordic Naturals, could not be properly evaluated because it contained lemon oil, and there are no industry-standard tests that Consumer Reports could find that could test for spoilage in products with lemon oil. Nordic Naturals did meet every other quality measure in the study, though.

How To Find The Best Fish Oil Supplements

The authors say even the brands that passed all their quality measures contained at least some detectable level of most of the contaminants. A spokesman for the dietary supplement industry says PCBs are everywhere in the environment, especially in fish. The tests picked up only very trace amounts of the contaminants that were within the limits set by the USP and European Union.

“The big take-home (message) is that all 15 supplements passed all laws and regulations as far as quality, as well as voluntary regulations for USP levels for toxins,” says Duffy MacKay, vice president of scientific and regulatory affairs at the Council for Responsible Nutrition.

He advises that people looking for a quality fish oil supplement follow these steps:

  • Look for companies that disclose their results for testing for environmental contaminants.
  • Look for supplements that have third-party verification, such as USP.
  • Bite into the capsule to make sure it tastes fresh and not “fishy.”

Researchers say fish oil supplements may help people who are at risk for heart attack and stroke by helping to prevent hardening of the arteries.

But the science behind other health claims is still evolving. Some evidence suggests that fish oil supplements may ease menstrual cramps and rheumatoid arthritis pain and help a host of other conditions, such as osteoporosis, ADHD, kidney disease, and bipolar disorder.

“Fish oil is not a cure-all,” Sandroff says in the release. “If you’re considering a fish oil supplement, we recommend that you talk to your doctor first to find out if it’s the right treatment for you.”

This article was published in WebMD. Photo by ion-bogdan dumitrescu.

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