Omega-3 Fatty Acids

Are omega-3 capsules contaminated?

 In this study, the average PCB and DDT intakes were calculated to be 736 and 304 ng/day, respectively.

But what does that mean? And is it important?

First, the details.

  • 30 samples of omega-3 fatty acid supplements were collected in Vancouver, Canada, between 2005 and 2007.
  • All oil supplements were analyzed for polychlorinated biphenyls (PCBs) and organochlorine insecticides (OCs).

And the results.

  • Each sample contained detectable residues.
  • The highest PCB and DDT concentrations (10,400 and 3,310 ng/gram, respectively) were found in a shark oil sample.
  • Lowest levels were in supplements prepared using mixed fish oils (anchovy, mackerel, and sardine) (0.7 ng PCB/gram and 0.2 ng DDT/gram).
  • Average PCB concentrations in oil supplements ranged from 12 to 5260 ng/gram (unidentified fish, mixed fish containing no salmon, mixed fish with salmon, salmon, vegetable with mixed fish, shark, menhaden, and seal).
  • Maximum concentrations of the other OCs were observed in the seal oil.
  • The hexachlorinated PCBs were the dominant contributors to PCB levels, while DDT was the greatest contributor to organochlorine levels.

The bottom line?

Average intake estimates of PCB and DDT were calculated to be 736 ng/day and 304 ng/day, respectively.

Ocean Nutrition Canada, a manufacturer of omega-3 fish oil ingredients used in foods and supplements attempts to put all this into perspective. “Fish oil primarily is sourced from the Peruvian Anchovy fishery [the source of the lowest levels fo PCB and DDT]. These fish are low on the food chain and are vegetarians, primarily consuming algae. This means they are very pure from contaminants as a starting source, compared to species such as seals and shark [the highest source of PCB and DDT], which are high on the food chain and accumulate contaminants.”

The Global Organization for EPA and DHA (GOED), an omega-3 trade association, adds that seal and shark oils are “obscure products that are actually difficult to find.” The group’s executive director Adam Ismail states that these products are outside the scope of the GOED voluntary monograph, which sets quality standards for fish oils.

“The other thing the study highlights is that in many instances omega-3 supplements can be a safer source of EPA and DHA than actual fish consumption, with a single serving of salmon containing more than 100 times the PCBs than the standard fish oil supplements used in the study, and 30 times more than the limits in the monograph,” concludes Mr. Ismail.

2/2/09 22:02 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.