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. This is the fifth video in a nine day series on vitamin D. Be sure to check out yesterday's video-of-the-dayVitamin D and mortality may be a U-shaped curve.

Also, check out my associated blog posts for additional context: Eating To Extend Our LifespanVitamin D: Shedding Some Light on the New Recommendations, and Vitamin D from Mushrooms, Sun, or Supplements? 

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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. This is the fifth video in a nine day series on vitamin D. Be sure to check out yesterday’s video-of-the-day Vitamin D and mortality may be a U-shaped curve.

    • Ali Canani

      Hi Doctor,
      I noticed that since I started taking Vitamin D3 supplements, I feel really itchy all over. Could that be related to the D3 supplements? The onset is usually within an hour of taking it and it takes a few hours for me to stop itching. If it is related to the D3, what are the alternatives in winter?
      Thanks for your help.

  • filippodibari

    In some European countries, Vit D supplements prescription to adults over 70 years of age, with ostheoporosis, consists of monthly dosages of 25.000 IU (=820 IU/d considering 30.5 days/mo).

    IOM Upper Level is 4000 IU/d.

    Question: any study about the possible toxicity for such a large monthly dosages?

    NB: I recall similar questioning about Vit A mega doses in large national campaigns in developing countries in the last decade.

    I could not find anything so far on PubMed for Vit D.

    Thanks Dr Greger.


  • DrDons

    Hi filippodibari, I do not think a single monthly dose of 25,000 would lead to toxicity based on information at this time. Your concern is well placed though… since we have a history of making recommendations only having to change them after finding out about toxicities later.

  • vfayes

    Dr. Greger — have you heard about the new vitamin D3 spray? What is your opinion — helpful? Harmful? Waste of money? Thanks!

    • Michael Greger M.D.

      Based on their current pricing, supplementing with that product would cost hundreds of dollars a year. Given the fact that at the preferred daily dosing D2 and D3 appear to be equivalent, I would suggest choosing a less expensive option (D2 is easily 10 times cheaper). Just think about how much kale you could buy with all the money you save!

      • JG

        im guessing from the above comment that you feel D2 is just as effective as D3?  i’m vegan and recently found out im very deficient in D.  from what i’ve read, i got the impression that D3 is more absorbable and d2 could be toxic.  I would much rather take D2 b/c of my moral concerns..but i was scared into taking D3!  what is your opinion on this matter?  thanks so much in advance.

  • Michael Greger M.D.

    For some context, please check out my associated blog post Vitamin D: Shedding Some Light on the New Recommendations!

  • Lidia Varvari

    Dear Dr. Greger,

    Thank you for this interesting video!

    Could you provide us with a list of the best oils/butters to use as a sunscreen (including a range)?

    Thank you so much!

  • Gina

    Hi. thanks for the videos. What about dosing for children? I started giving my 9 & 11 year old children 1000iu/day. Is this safe for them?

  • Tim Janning

    I try to follow a whole food, plant-based diet and I favor Dr. McDougall’s starched based diet. I watch Dr. Gregor’s videos frequently and I find myself conflicted regarding the efficacy of using Vitamin D supplements. It seems Dr. Gregor recommends the use of them; whereas, Dr McDougall does not. See . Dr. McDougall states that these supplements do not have benefit at least as far as bone fractures are concerned and may have negative side effects. Dr. Gregor emphasizes studies regarding overall mortality and the level of vitamin D to be at that optimal level (2000 iu daily). I live in the Seattle area where many days may go by without sunshine. Questions: 1. Does the body produce vitamin D if outdoors even with cloud cover? 2. Are there studies that demonstrate the negative side effects of vitamin D supplements? 3. Dr Gregor’s video seems to suggest that there is no natural means of maintaining an adequate level of vitamin D without supplements so that suggests that perhaps the levels recommended are inflated. Does this seem plausible from available research?

    • Joseph Gonzales R.D.

      Hey Tim, Thanks for reposting this question. Vitamin D seems complex and doctor’s may have varying opinions based on the populations they serve. The choice is yours, as there is not a perfect answer. Know that there will be many more vitamin D videos from Dr. Greger to come, so stay tuned…

      Here is Dr. Greger’s take on vitamin D. Perhaps there is more to vitamin D beyond bone health? Dr. Greger mentions if vitamin D supplements are necessary in this video (the one above) and whether we should obtain vitamin D from sunshine, mushrooms or supplements here. You can also see his video on cancerous tanning beds.