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Pregnant Vegans at Risk for Iodine Deficiency

Disinfectants used to sanitize cow udder may provide a source of iodine for dairy consumers but can also increase the concentration of pus in milk from cows with staph infection mastitis.

September 8, 2011 |
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Supplementary Info

Sources Cited


Images thanks to Tyabji [GFDL or CC-BY-SA-3.0] via Wikimedia CommonsPhotos by Lina, and Cafe Press.


The mineral  iodine is important for thyroid function, but during pregnancy is critical for fetal neurological development. Even a mild deficiency can impair cognitive ability.

The derogatory word cretin, was originally a  medical term describing those with stunted physical and mental development  due to an untreated congenital iodine deficiency.  It remains one of the most common preventable cause of brain damage worldwide, because of iodine deficient soil, which is why most table salt is iodized.

 “Iodine can also be found in dairy products due to iodine supplementation of cattle feed and it leaches into the milk from the use of iodine containing disinfectants to wash the udders, dip the teats, and clean the milk tanks out with. Dipping the teats in iodine can decrease the bacteria concentration,  but in cows with staph mastitis can actually increase the pus content in milk as much as 60%. Regardless,  “The iodine content of dairy products contributed by sanitizing products may not be well regulated and may not be a nondeliberate source of iodine, but it is a source of iodine nonetheless.

 These considerations therefore “raise concerns about the iodine status of pregnant women and women of reproductive age who are not consuming dairy products.” So, last year they concluded,  “Iodine levels among U.S. women should be monitored, particularly among subgroups at risk.” Good idea,  so this year they did it: “Iodine Status and Thyroid Function of Boston-Area Vegetarians and Vegans.” How did they do?

One way to measure iodine status is with a urine test.  The World Health Organization recommends we should average a 100 micrograms more in our urine, unless we’re pregnant in which case we’d really like to see it up around 150.  This is where vegetarians came out, not bad:  “U.S. vegetarians are iodine sufficient.”

 What about the vegans? 78.5. That’s not good. The  findings suggest that U.S. vegans may be at risk for iodine intake.Therefore: “vegan women of child-bearing age should supplement with 150mcg of iodine daily.”

The best new resource for those planning a plant-based pregnancy is probably  Vegan for Life by Norris and Messina, released July 2011. 

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.

To help out on the site please email

Dr. Michael Greger

Doctor's Note

For details on exactly how much iodine we need and the practical tips on the best way to get iodine (without the pus), check out one of my earlier videos: Avoiding Iodine Deficiency.

For even more context, check out my associated blog posts: Do Eden Beans Have Too Much Iodine?How much pus is there in milk?, and Heading Shrinking from Grilling Meat

  • Michael Greger M.D.

    See the corresponding blog post How much pus is there in milk? For details on exactly how much iodine we need and the practical tips on the best way to get iodine (without the pus), check out one of my earlier videos: Avoiding Iodine Deficiency.

  • Eric Needs

    this isnt really related, but how does this make you feel? makes me a little queezy

    • Michael Greger M.D.

      Thanks for pointing that out–do you want to repost that comment in one of the organic foods videos? Maybe in Can Pesticides Be Rinsed Off? That way people interested in organics won’t miss out on your post!

  • Heidi Woodruff

    Dr Greger I have a friend who drinks low fat soy milk at home but skim milk cappuccinos when out because she is worried that the full fat soy milk they have at cafes has too much fat (she is watching her weight).
    What can I tell her?

    • Michael Greger M.D.

      You may want to send her the link to Hormones in Skim vs. Whole Milk so she can be fully informed before she makes her decision.

  • Eric Needs

    i will!

  • Kate Veltkamp

    Dr. Greger, I’m a pregnant vegan taking a prenatal vitamin that supplies 150 mcg of iodine. Am I still at risk for deficiency? Thank you!

    • Toxins

      As the good doc pointed out, prenatal vitamins have folic acid and iron which may harm your baby.

  • Michael Greger M.D.

    Please also check out my associated blog post Do Eden Beans Have Too Much Iodine?

  • Don

    My bride and I very, very seldom add “salt” to our foods. to supplement our iodine intake, we take “sea kelp”. Don :-))

    • Alex

      Hi Don, I hope all is well with you and your family, more than nine months later! I eat kelp occassionally but only recently learned it has enormous quantities of iodine. From the numbers I’ve seen 100g dried kelp can have about 60 000 mcg of iodine (not quite a fatal dose, but way over the recommended upper limit). I’ve chopped my dried kelp into hundreds of stamp sized strips for a daily tab. I also soak the kelp a bit before using to remove the occassional ‘crunch’. I assume that lowers the salt content but probably not the iodine.

  • Elissar Gerges

    Dear Dr. Greger,
    I am 4 weeks pregnant and i’m vegan. I have watched your videos and I am concerned about iodine and vitamin B12. I eat a healthy varied diet of fruits, vegetables, nuts, beans and other legumes.
    Should I start taking vitamin B12 and iodine supplements? What do you suggest?
    Thank you

  • Svetemel

    Dear Doctor Greger, do you have any data on whether alcohol free beer is safe during pregnancy? The data in internet is quite contradictory. Many thanks in advance.

  • Technus

    What about cranberries, seaweed or baked potatoes, aren’t those good sources of iodine? I will probably start eating cranberries everyday again like I used to.