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Looking back: A vitamin D toxicity review from 1937

Posted on: November 20, 2013   by  John Cannell, MD


A few days ago I ran across a unique 1937 paper. It was commissioned, in part, by the American Medical Association and appeared in the prestigious Annals of Internal Medicine. The paper was about the toxicity of mega doses of vitamin D.

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9 Responses to Looking back: A vitamin D toxicity review from 1937

  1. Rita and Misty

    I enjoyed this article very much.

    A word on canines and vitamin D:

    Mistygirl, my Australian Shepherd, is a rescue dog. We estimate that she is between 13-15 years old. She is approximately 60 lbs. And, she has been supplementing with D3 for going on 3 years now. She takes a conservative 4,000 iu D3 WEEKLY.

    Misty is an old dog. But, she has no health problems associated with her breed. She has no hip dysplasia…no dental or gum problems…no eye problems. She is extremely healthy.

    Misty used to run 6 miles every day. But just this past year she can no longer keep this pace. Now, I am sad to say, she can only walk 3 miles a day. But, she truly looks forward to these walks. She has no idea she is old. She has the heart of a much younger dog. I would venture to say few Australian Shepherds make it to age 15 with no health problems whatsoever. I think Mistygirl is truly lucky.

    I often consider upping her dosage of D3, but I am afraid. I would take more health risks on myself than on Mistygirl.

    (If people were more like dogs the world would be a happier place).

    Be well,

  2. IAW

    To: Vitamin D Council
    Just wanted to say thanks so much to you for deciding to publish this blog. I really do understand that you do not want people to get “carried away” by how much Vitamin D they take and yet you really do need to give information to dispel the “myth” that it is dangerous!.

  3. Magic

    I worked in the investment business. I was always disappointed when a small company with great ideas in health care wouldn’t have enough money to continue. Enough was often a couple of hundred million dollars which they ran out of. I felt it was the FDA’s fault in requiring a company to spend in the billions to get a hot product approved. Now as I have reason to see lots of end of life situations I am firmly convinced that IAW is right. Vitamin D3 is suffering from such a myth. We were fired by one doctor who said that 1000 IUs a day was toxic and wouldn’t listen to or read about anything different.. My wife’s next doctor told her the same thing…(A pretty good chance that both doctors have the same sales rep.)

    Our health care situation will keep the US in the middle of the pack and our costs will continue to rise until somehow things are changed. I do not give it much hope.


  4. Rita and Misty

    I choose to keep my 25(OH)D level at the higher end of optimal, range defined as between 50 ng/mg –80 ng/ml….

    I am always grateful for the Vitamin D Council, and the courage of Dr. John Cannell to post articles such as this one, upon which we are, all of US, commenting.

    I understand that the Vitamin D Council is in no way recommending mega doses, or anywhere close to them.

    Here is the problem as I see it (and I am not a researcher nor am I a physician–just an outspoken woman–though I have tried to tone my outspokenness down to an appropriate level):

    There is no consensus within the vitamin D community as to optimal reference range for the 25(OH)D level. If there is little agreement amongst those who have studied vitamin D, how does anyone propose we go about educating others in mainstream medicine…those who have historically been taught in med school that vitamin D can be toxic?

    Yes, studies like this 1937 study do help…but it isn’t enough….

    I have said it before…I will say it again (BTW, I am turning blue): consensus within the vitamin D community is the first step….

    (NB: When I talk to those in my daily virtual existence, they are quick to point out lack of consensus.)

  5. [email protected]

    I have to assume that the D used in this study was D3, not D2 because 1937 was before development of the patent drug D2. Y/N?

    Pressure to ignore Steck et al’s work obviously comes from the Medical Industry because it is an old study and old scientific studies like these lose relevancy with age for some mysterious reason. In addition, the MI has nothing to gain and a lot to lose, financially, if a significant proportion of the populace normalizes their 25(OH)-D3 levels and they are well aware of that.

  6. Rogerio Luz Coelho

    I am thrilled by this study …

    Body of evidence has been poring on ideal 25-OH … but people are still very scared to publish their findings, and publishing anything in Vitamin D is not a easy task. I have an epidemiologic study with professional football (soccer players) that show that even in pro footballers in Brazil we have somewhat of >20% deficiency (and I assume 30 ng/dL as enough) and am having trouble to publish it (even in english journals).

    So is the difficulty right now for Vitamin D research.

    Cheers πŸ™‚

  7. Rita and Misty

    So Misty went to the vet’s office yesterday morning. The vet said that for around 15 years of age Misty is doing fantastic. Much more like a 10 year old doggie than a 15 year old. The vet thought it perfectly fine for Misty to take vitamin D3 supplements…and said that my giving Misty 4,000 iu D3 per week was quite conservative…and that this dose in all likelihood could be raised by weight…. Misty weighs 50 lbs… (the appropriate dosage wasn’t discussed, unfortunately…so I am left to guess whether canines can be dosed similarly to humans…) BTW–the vet herself is a big (huge) advocate of D for humans…but she refused to comment on her daily dosage…. (sigh)… bittersweet… πŸ™‚ πŸ™ πŸ˜‰

  8. [email protected]

    hello Rita and Misty

    I gave my Golden 50 000 IU per month and I will do the same again, when I get a new one.

    Elisabeth πŸ™‚

  9. Rita and Misty

    Thanks Elisabeth ! I’ve already started to give Misty 2,000 iu every other day. I am going to start her on 2,000 iu daily….

    She is an awesome Australian Shepherd, and I would like her to make 20–only in good health, of course.


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