How much Vitamin D is Safe?

Q. I’ve read a lot about the health benefits of Vitamin D. But isn’t there also a limit of how much Vitamin D I should supplement? Is there a danger or limit that avoids a possible toxic amount?

A. The Institute of Medicine recently doubled the safe upper limit (UL) for vitamin D from 2000 IU to 4000 IU. That’s still quite a bit lower than the 10,000+ IU a day that some vitamin D researchers recommend. The IOM tends to be rather conservative and research suggests that 10,000 IU a day is unlikely to cause problems.  But I think the IOM may be trying to provide a counter-balance to what some see as “irrational exuberance” being displayed by some vitamin D aficionados.

The science on Vitamin D, while compelling, is still quite immature. While low vitamin D status has been linked to a number of health problems, we still don’t have strong evidence showing that high dose vitamin D supplements make or keep people healthier.  In fact, And I just saw some research suggesting that a combination of dietary vitamin D (from food and supplements) and moderate sun exposure (which triggers vitamin D production in the skin) offers the most benefit.

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Related Content:

See also my podcast on Vitamin D as well as this interview on WYPR.

5 thoughts on “How much Vitamin D is Safe?

  1. Vitamin D from sunshine and diet are quite adequate, according to all the studies I’ve reviewed and researchers I’ve been in touch with, thus no one needs to take supplements which may only do harm.

    A related article which you may not have seen:

    http://escholarship.org/uc/item/4m84d4fn

    T.A.

  2. Hello!
    My Vitamin D level came back at 34. Range is 30.0-100.0. My PTH, intact came back 29, range is 15-65. I was wondering if I should take a supplement to up my D level?
    I eat a clean diet and am in stage 3 kidney failure under a Doctors supervision. ( I was stage 5) I was told take take a calcium supplement, so I bought it with D in it. It’s 250 Iu of Vitamin D and 600 mg calcium. I do take it BID.
    I am 35 years old and would like to ward off any bones issues later in life.
    So, my question is how much Vitamin D should I start to take?
    Thank you for your feedback. I hope you can help me!
    -Suzanne

  3. Suzanne —

    I would strongly advise you to forget about supplements and obtain your calcium and vitamin D from foods and sunshine only. The calcium in supplements tends to be either excreted or diverted to arteries and organs, rather than benefitting bones, and vitamin D in supplement form only makes matters worse. Choose whole milk, not low-fat or skim, and avoid all refined oils. You can’t do better than that.

  4. Thanks Thomas for your feedback.
    I will look into calcium rich foods and Vitamin D foods. I never thought I would of had this problem but my kidneys thought other wise. Actually, it’s the hormone in my neck that thought other wise. Hyperparathyroidism is the name of it. This is secondary to my kidney failure. Which then effects my phosphorus level, which effects my vitamin D level. Crazy stuff but it’s what I have. I am happy to be alive!
    A little more sunshine won’t do me harm anyway.
    Thanks,
    Suzanne

  5. I just got word from my doctor’s office that my Vitamin level was low and I have to up my intake by 1000. I have osterporosis and have been getting prolia shots,I am 73 years old and live in Canada where the sun is not around in the winter. Was wondering the amount I should have,I take Soya milk,yogurt,fish,fruit and greens.

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