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Mercury in Vaccinations vs. Tuna

Balancing the risks and benefits of fish consumption.

September 11, 2008 |
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Supplementary Info

Sources Cited



There’s been dozens of risk-benefit analyses lately, looking at nutrient and contaminant tradeoffs. Fish consumption provides nutrients, but all fish also provide methylmercury, a known neurotoxin. The more fish you eat the more omega 3’s you get, but the more fish you eat the more mercury you get too. Mercury is a cardiac toxin as well. So while fish omega 3’s are decreasing your risk of a heart attack, the mercury in that same fish is increasing your risk of having a heart attack. So studies like this look through the various species. Salmon has less mercury than tuna, but tuna has less dioxin. The only truly healthy fish in the world would be some fanciful creature made out of dark green leafy vegetables.

Once upon a time, routine childhood vaccinations used a mercury-containing preservative called thimerisol. I was always amused by parents who fed their kids tuna—yet, didn’t want vaccinations because they didn’t want to expose their childlen to mercury. Eating a single serving of tuna is the equivalent to getting injected with how many thimerisol-containing vaccines? One… hundred! One serving of canned tuna.

Sure, dietary exposure to mercury may harm child development, but if you cut down on fish you may get less omega 3’s. So they get out their calculators. In a city about the size of New York, if pregnant mothers ate lots of fish, because omega 3’s like DHA are so beneficial to brain development one would expect to see an improvement in 209,000 years of children’s lives (what’’s called quality adjusted life years). But at the same time the mercury in that very fish would damage 203,000 of children’s life years. So they do the math, comes out positive by a hair and you hear on the news such and such medical authority says the benefits outweigh the risks, eat fish.

Now of course this doesn’t take into account the dioxins, PCBs, which tip the scale the other way, but more importantly: why accept any risk at all? By getting DHA from plant sources you can get all the benefit, with none of the risks. All the benefit without the hundreds of thousands of life years of brain damage.

This reminds me of the dairy and calcium thing. Every time they come out with yet another study linking dairy consumption with something bad, they get out of saying “stop drinking milk” by ending the article with “but one has to balance the risk of cancer, or diabetes or whatever with the risk of not getting enough calcium.” As if the only source of calcium on the planet were dairy—where do you think cow gets it from in the first place? Plants. And the same thing, with DHA. Where do you think the fish get it from? Plants, and we can too—little tiny plants called golden algae.

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 Dianne Moore.

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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. Also, there are 1,449 other subjects covered in the rest of my videos--please feel free to explore them as well!

For more context, check out my associated blog post, Mercury Testing Recommended Before Pregnancy

  • sarahharmony

    i wish i had found this before i fell pregnant – am 8 months along now but better late than never! Am really enjoying your website – thankyou.

  • 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. Also, there are 1,449 other subjects covered in the rest of my videos–please feel free to explore them as well!

  • Janjan

    Saw you speak at the NHA convention, really enjoyed your style of delivering a very important message. I’m here at the Regency health spa detoxing from sugar and aspartame.

  • Didi Nour

    why i can’t see any discussions anymore!

  • gary

    Understood that we should limit or eliminate fish intake, but what about the argument here?

  • Melanie Glover

    thank you for this

  • Ilana

    They still have mercury in vaccines. Is that a concern? I assume you are a proponent of vaccines, that the protection outweighs the risks? (Even though vaccines are not technically vegan.)

    • shayneo

      No. The amount of methylmercury in vaccines is so low the harm can’t even be calculated. There have been plenty of studies and no evidence of harm has been found.

    • Don Forrester MD

      Mercury is always a concern and has to be balanced against the benefit. You can insist on getting immunizations from a single dose vial. The single dose vial do not need to have a preservative in them.

  • Mark

    isn’t an injected mercury meaningfully more toxic than mercury eaten in fish? Doesn’t every dose of mercury accumulate in the body?

    • Don Forrester MD

      No. It has to do with the dose. Organic mercury is very well absorbed by the GI tract. The amount of injected mercury has to be compared to the amount in food such as fish. Also consuming fish which is the greatest source of mercury in the diet comes along with other contaminants such as dioxin, insecticides and even drugs. You might view videos on fish to see the extent of this problem. Mercury is best avoided.

  • Ray

    Hi Doc,

    I was just wondering if you exercise any scientific skepticism when reading the literature for your videos? Do you wait a little while to see what comes out of the post-publication review of the articles? Just because there is a single study with a certain result does not mean that it reflects the direction of the literature. Just curious as to what methods you use.

  • matt

    Hi Doc

    I was just reading about thimerosal. The mercury in thimerosal is an inorganic ethyl mercury as opposed to the methyl mercury in tuna. Isn’t ethyl mercury processed more easily by the body. If that is the case, is it even fair to compare thimerosal and tuna?

  • Claire

    Enjoying every topics as they are presented by Dr Greger with finest and a real passion. Any insight on tinnitus relief? Thank you for any suggestions that might reduced tinnitus by even a decibel. Claire