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Is Distilled Fish Oil Toxin-Free?

Researchers test molecularly distilled fish oil supplements for industrial pollutants.

December 1, 2010 |
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Fact of fiction: fish oil decreases inflammation. It better—that’s a main reason people take it. But it’s not true… No effect of fish oil supplementation on inflammatory markers. This randomized, double-blind placebo-controlled intervention trial showed no effect of a whopping dose of fish oil on markers of inflammation in the blood. If anything, there was a trend that all serum inflammatory markers tended to increase after fish oil.
Wait a second. The whole reason people are told to eat fish, told to take fish oil is that the long chain omega 3 fatty acids like DHA are anti-inflammatory. So there must be something in the fish oil counteracting the good stuff and increasing inflammation, and it’s likely the industrial pollutants, such as PCBs d insecticides.
We now know, that PCBs can induce the kind of inflammation that promotes obesity and heart disease. It’s the same reason polar bears are now suffering from chronic inflammation: the industrial contaminants in our oceans that build up in fat. And so when we swallow capsules containing straight fish fat it puts us at the same tenuous polar bear position at the top of the food chain.
So, what about distilled fish oil? You’ll see things like this: molecularly distilled. Molecularly distilled for maximum purity. Well, researchers put fish oil distillation to the test last year. Fact or fiction, fish oil is safe—but only if it’s distilled. Fiction. It’s not safe.
They found the same PCBs and insecticides, even in the supposedly “PBC-free” fish oil. And the exact same levels of other industrial pollutants. The bottom-line: “This suggests that the commercial molecular distillation treatment used for removal of toxic contaminants is only effective for some of the contaminants. So, they conclude, that you have to balance the trade-off between risks and benefits, especially given how ineffective current fish oil treatments are at removing some of these contaminants.
That’s why I recommend the algae-based DHA—a win-win for humans, so you can get the benefits without any of the risk.
Because our oceans are so polluted, even when you buy distilled fish oil… you can’t get off the hook.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring watch the above video. This is just an approximation of the audio contributed by veganmontreal.

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Dr. Michael Greger

Doctor's Note

Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. And check out the other videos on fish oil. Also, there are 1,686 other subjects covered in the rest of my videos--please feel free to explore them as well!

For some context, please check out my associated blog posts: EPA dioxin limit has National Chicken Council worried products could be declared “unfit for consumption”. and Treating Crohn’s Disease With Diet.

If you haven't yet, you can subscribe to my videos for free by clicking here.

  • Michael Greger M.D.

    Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. And check out the other videos on fish oil. Also, there are 1,449 other subjects covered in the rest of my videos–please feel free to explore them as well!

    And check out my associated blog post EPA dioxin limit has National Chicken Council worried products could be declared “unfit for consumption”.

    • healthedsamurai

      Dear Dr. Gregor,

      I’ve read the labels of several algae-based products and they have good amounts of DHA, but minimal EPA. Do you see this as a problem? Don’t we need both, and in relatively equal amounts? Is there a product you are aware of that does have sufficient amounts of both? How important is EPA as compared to DHA, and why dosen’t algae produce much EPA?

      • DrDons

        EPA is metabolized to DHA which then is converted to the antiinflammatory and anti clotting substances our bodies need. So taking in adequate DHA would be enough and you need not worry about increasing the amount of EPA. Studies show that the supplements work…See video for more information:

  • kjcreate

    Dr. Greger,
    Please indicate if studies support AJ of Epidemiology 4/24/11 report that men with higher levels of DHA were 2 1/2 times more likely to have an aggressive form of prostate cancer. What about contaminate free form of DHA, like MorDHA prenatal, EMAS status (most stringent European standard). ps does Algae also support eye health?

  • nlockwood73

    About 6 months ago I started a plant based diet to lower my cholesterol, among other ailments. I have been taking flax seed oil capsules, but I have heard that fish oil is more effective than flax seed oil. My diet did lower overall cholesterol 30 points in 10 weeks and my triglycerides were reduced by half. Is there a benefit to algae vs. flax supplements for cardiovascular health?

  • DrDons

    The short answer is that fish oil is not effective and comes with contaminants & saturated fats which are harmful. Since fish get the omega 3 plus EPA & DHA from plants (i.e. algae) you should eliminate the middle “person”. This eliminates the bad stuff and the fish come out ahead as well. The omega 3/omega 6 issue is a bit complicated. In 2003 Dr. Greger did a presentation on heart disease and nutrition which is now available as an 8 part series on YouTube (Dr.Greger’s Optimum Vegetarian Nutrition). Parts 3 and 4 of those talks explain the whole issue including DHA, EPA and AA issues as well as any that I have seen. I would review those to better understand the issue. The links for these are: (Part 3) & (Part 4). Some experts claim that if you consume a whole food plant based diet plus avoid processed oils you don’t need to take a supplement for EPA & DHA. As Dr.Greger points out this can be difficult to do so he recommends a 250 mg supplement daily. If you are going to supplement you should use an algae based product of which there are several see: This is especially important for women who are pregnant and breast feeding. Congratulations on your progress and keep tuned to for more of the latest science.

  • Karen

    Thanks for the great info..Isn’t algae also potentially contaminated due to being from the same polluted ocean? I especially avoid anything from the Pacific Ocean since Fukishima..

    • Rebecca

      Many or maybe all(?) algae DHA supplements are grown in a lab – check the labels or websites.

  • Paul

    1.5 grams in the study is below the therapeutic dose recommended for fish oil which is in the 3 to 5 gram per day range. Not advocating fish oil, algae oil is still better but it’s a straw argument to say that no effect at 1.5 grams means fish oil cannot anti inflammatory. Need better QA here.

  • Norma Chabot

    Hello I use Usana Health Sciences Bio Omega Fish oil does it have contaminates?
    Norma Chabot

    • Don Forrester MD

      I don’t understand why anyone would consume fish oil and run the risk of contamination. The fish don’t make the DHA, EPA or omega 3′s that the body uses to make those substances. Since as Dr. Greger’s video’s point out their are acceptable alternatives that eliminate “the middle person aka fish” from the whole process. Of course then the question is should the general population consume omega 3′s as a supplement. As a general rule the only supplement you need on a plant based diet is Vitamin B12. The use of other supplements should be based on the individual patient’s situation.

  • Doug

    Would reverse osmosis be any better at filtering out toxins?

  • Israel Navas Duran

    I fail to see the evidence of a cause-consequence relationship between:

    1. the presence in fish oil of PCBs, organochlorine pesticides, polybrominated diphenyl ethers, brominated HNPs, and

    2. the lack of the effect of its supplementation on the serum concentration of a number of cytokines, chemokines or cell adhesion molecules as compared with placebo after 3 weeks.

    There are several alternative explanations to this “lack” of anti-inflammatory effect (I’d have liked to see the concentrations of other inflammatory markers such as CRP, directly linked to the risk of developing cardiovascular disease).

    Only a direct comparison between the effects after fish oil supplementation and a supplementation with omega-3 EPA and DHA from non-animal sources at an equivalent dose will actually tell us whether there’s a clear difference in the effect dependent on the source of the omega-3 supplement.

  • marble

    In this line of thinking we shouldn’t eat any fish? (suplement or not) Are anything in nature that isn’t contaminated? Should we stop eating?

    • Toxins

      Fish is by far the most contaminated animal food one can consider eating. Dr. Greger does indeed encourage we do not consume fish.