Doctor's Note

This is the seventh video in a nine-part series on vitamin D. Be sure to check out yesterday’s video: The Difficulty of Arriving at a Vitamin D Recommendation.

For additional context, check out my associated blog posts: Vitamin 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 seventh video in a nine day series on vitamin D. Be sure to check out yesterday’s video-of-the-day The difficulty of arriving at a vitamin D recommendation.

  • paul3917

    In the list of tissues involved with vitamin D, there’s something called the eggshell gland. What’s that? Do humans have this eggshell gland or is it found in birds only?

    • Michael Greger M.D.

      Good eye! That’s just in birds and some fish and reptiles (though presumably in platypuses as well?). It’s part of their oviducts that forms the eggshells.

  • murtaza

    hello, can u let me knw wat are the effects of vit D deficiency in adults..and wat if the level is below 5 ng/ml..?

  • DrDons

    The effects of Vit D deficiency are many as you can see from the list on the right side of this video’s diagram. It is always difficult to say which effects occur in an individual. However a level of 5 ng/ml would be considered deficient by any recommendations. For further discussion see: The best way to keep our vitamin D levels at the appropriate level is to get adequate sunlight see: For individuals with very low levels as you mention I would recommend working with a physician to get recommendations and appropriate followup.

  • ajwagner

    There was a NY Times story several days ago noting a study suggesting that CRP levels went up once blood Vitamin D levels reached 21ng/ml. ( ) Would this have any effect on your recommendations on Vitamin D supplementation?

    • JoAnn Downey

      My CRP was under 1 and my D3 level was 40ng/ml

  • Michael Greger M.D.

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

  • autumn jasmyn

    Can ;post-menopausal women take vitamin D supplements? I read somewhere that Vitamin D was not recommended for that supplementation. I would like to know the correct answer. Thank You!

  • Claudi

    Hello, it is possible, when many year not in the sun,and you have only 9 from 40 or 50 nmmol you geht trouble mit Parahytroid? I have hyperparathyroidism with 1 cm ademom? Can I lose the ademom, when eating vegan with much vegetable?

    There are studies hyperparathyroidism relating and nutrition? Thanks

  • brukburk

    Feel free to jump to the question below. I searched the site and haven’t found anything on hyperparathyrodism. There are so many stories out there that are “Pro-vitamin D” however if one has hyperparathyroidism, vitamin d can make you very ill. This happens to me. I had all the symptoms of hypercalicemia. My vitamin D level at this time was 30. Once I stopped taking vitamin d, all my symptoms went away. Since then, my D plunged back to 15 and yet I still have a tan from the summer. I finally had one high parathyroid test even though my calcium is normal. I’m 41, and patients my age ususally do not have hyperparathyroidism but my experience with vitamin d and becoming ill made me aware that something was not right in my body.

    My Question:
    What I am wondering about is that I’ve read that there is a correlation between severe obesity and parathyroid tumor growth, that is, the more obese, the larger the growth. So my question is, if one is “severely obese” based on BMI, then would it be possible or plausible if one were to lose weight and reach a healthy BMI, that one could reverse tumor growth and heal one’s self? Like in the case of some other systemic diseases like diabetes, if one removes the causation of the condition? Or once a tumor is there, can it only be removed via surgery? Also, is there any other research that points to the cause of hyperparathyroidism? Is it also a disease of the western diet like diabetes, heart disease, and stroke?