Doctor's Note

Also check out: Is Fish Oil Just Snake Oil?

And check out my other “HHH” videos (Harmful, Harmless, or Helpful?)

For further context, see my associated blog post: Soy milk: shake it up!

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  • 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 “HHH” videos (Harmful, Harmless, or Helpful?). Also, there are over a thousand subjects covered in the rest of my videos–please feel free to explore them as well!

    • Susan Fairbairn nee Kirk

      I would be interested in hearing the answers to the above questions?

      • Toxins

        above question has been answered by myself, please view the responses.

  • ncibotti

    I’ve been using Arctic Cod Liver Oil from Nordic Naturals for years. I’ve also been giving it to my 7 year old son for years. I’m deeply concerned about the possibility of liver damage due to high levels of A. Are you recommending that we no longer use cod liver or fish oil supplements?

    • According to the bottle of the Nordic Cod Liver Oil, there is only 650 IU of vitamin A per serving (about 13% of Daily Value). This is no where near toxic levels. I’m assuming that most other common cod liver oils off the shelves are no where near toxic levels either.

  • Deanna

    What is considered to be a toxic level of Vitamin A?

    • Toxins

      see my reply above

  • Tina

    Where is the answer to the question ” what is considered to be a toxic level of Vitamin A? I would like to know the answer too.

    • Toxins

      “Because vitamin A is fat soluble, the body stores excess amounts,
      primarily in the liver, and these levels can accumulate. Although excess preformed vitamin A can have significant toxicity (known as hypervitaminosis A), large amounts of beta-carotene and other provitamin A carotenoids are not associated with major adverse effects”

      Upper limits are capped at 3,000 IU’s so consuming 10,000 IU’s of preformed vitamin A is indeed toxic.

      More information on fish oil can be found here. The science indeed shows ill effects.

      • Connie Sanchez, ND

        In addition to the above risks, excess amounts of vitamin A have been shown to increase risk of bone fracture.

      • Karen Tough

        10,000 iu is the upper safe level for vit A !! people regularly consume 20 – 50000 iu without issue. Many people can’t convert betacarotene to Vit A & thought to cause cancer in smokers for this reason. Many believe since abandoning organ meats we don’t get enough & rdi should be higher.
        It is now known that we don’t convert beta carotene 1 for 1 either.

        • Toxins

          The safe upper limit is 3,000 not 10,000. People do not regularly consume mass quantities of preformed vitamin A as this would lead to toxicity. Your statements regarding beta carotene are untrue and unsupported. Please share evidence to back your claims.

          • Karen Tough

            3000 is the RDI !!! 10000 is the upper safe level.
            Wardlaws perspectives in nutrition , upteen govt sources & the cancer council. Do a search on google scholar.

          • Toxins

            According to the NIH reference tables, 3,000 is the upper limit.

          • Karen Tough

            those figures are ug/d (aka mcg) not iu’s – 3000ug= 10,000 iu’s.

          • Toxins

            Thanks for pointing out the discrepancy. Your absolutely right, I have confused the units of measurement.

          • Karen Tough

            no worries – I would appreciate it if you would correct the article/comments to prevent mis-information regarding intakes.

          • Toxins

            Sure thing.

    • Donna waterman

      What is th

  • Guest

    I have a

  • Laury

    I have an A vit deficiency, should I take cod liver oil? Or what would be best? Right now I eat goji berry.

    • Toxins

      Eating greens, sweet potatoes and many other yellow/orange plant foods provide plenty of vitamin A.

  • oliver

    if distilled=concentrated then perhaps, but distilled=purified to my knowledge, the levels of vit A in fish oil are not toxic. people can consume 10,000 iu with no toxicity.there is a difference between helpful advice and scaremongering- fish oil is the most important supplement today to combat our diets.

  • Mimi

    Recently, the results of a study investigating the effects of omega-3 supplements/fish oil on cognitive outcomes in children were published:

  • Rose

    If fish oil has no benefit, then why did my triglercerides go way down? When I stopped taking the fish oil, it came way back up again! I started to take fish oil again….my triglycerides went back down! WHY?????

    • Joseph Gonzales R.D.

      Hi Rose. I am not sure. I am glad they went down though, most importantly! This video is just mentioning cod liver oil and toxic levels of vitamin A.

      • manuel v

        Michael doesn’t talk at what levels its toxic. Everything is toxic at some level. There are studies that show health benefits.
        In general I find his videos most informative.

        When he creates a video like this I begin to question all his work. Which I hope is not warranted.

        J Am Coll Nutr. 2010 Dec;29(6):559-62.

        Cod liver oil, young children, and upper respiratory tract infections.

        Linday LA1.

        Author information


        liver oil contains long-chain omega-3 fatty acids, as well as vitamins D
        and A. It was a traditional source of vitamin D in the United States
        and was used to prevent and treat rickets. In our clinical research, we
        used liquid cod liver oil of adequate purity and acceptable taste for
        infants and young children, as well as a children’s multivitamin/mineral
        supplement with selenium and other trace metals. In a
        cluster-randomized study of pediatric visits for upper respiratory
        illness during the winter and early spring, these nutritional
        supplements decreased mean visits/subject/month by 36%-58%. Cod liver
        oil is culturally valued and has been used as a folk remedy by many
        low-income minorities in the United States. Nutritional supplements
        cannot be purchased with SNAP benefits (formerly called food stamps).
        Inclusion of cod liver oil in state Medicaid formularies would make it
        available to low-income children, whose families may not be able to pay
        for it out-of-pocket.