Q & A

Dr. Holick appreciates your comments and questions. While he cannot answer every question, he responds to as many as he can and will periodically post answers to questions here. Please submit your comments and questions in the window at the bottom of the page.

Some of these comments, and Dr. Holick’s responses to them, come from previous versions of this website. They have been re-posted here by this site’s administrator.

For more discussion of specific issues related to Vitamin D, and to download some of Dr. Holick’s original journal articles, click here to go to Dr. Holick’s other website, VitaminDHealth.org.


  1. Joanne
    Posted July 7, 2014 at 8:37 am | Permalink

    I have just been told my vitamin D levels are within the insufficiency range at: 34nmol/L they have prescribed Fulfilment D3 800 in daily is this normal?

    • admin
      Posted July 14, 2014 at 9:53 am | Permalink

      Dear Joanne,

      Unfortunately I doubt that 800 IUs of vitamin D daily will treat your vitamin D deficiency. I usually give my patients the equivalent of about 5000 IUs daily for 2 months to fill up the empty vitamin D tank and to keep it on fall I give them an equivalent of 3000 IUs daily forever. I personally take 4000 IUs daily and my blood level of 25-hydroxyvitamin D is 150 nmol/l which is equivalent to 60 ng/mL.

  2. Nupur
    Posted June 29, 2014 at 12:13 pm | Permalink

    My vitamin D level was at 15, so was asked to take 60,000 iu granules pack with milk, I was already taking 1000 iu capsules for a month before I took the 60,000 iu dose before sleeping at night. This high dose is making me extremely restless and causing insomnia. Is that a normal symptom?

    • admin
      Posted July 14, 2014 at 9:52 am | Permalink

      Dear Nupur,

      I typically recommend 3000 IUs of vitamin D daily and thus about 100,000 IUs a month. Unclear exactly how much you are taking. Normally vitamin D does not cause restlessness nor insomnia.

  3. Naveen Nahata
    Posted June 5, 2014 at 3:31 am | Permalink


    Yesterday only i have 25-OH vitamin D total test, found its very low 4.94 ng/ml.
    My question is why do i have so low vitamin D. However i am having enough sun exposure ? and what further action should i take ?

    Thanks alot.

    • admin
      Posted July 14, 2014 at 9:50 am | Permalink

      Dear Naveen,

      I am not surprised that you are vitamin D deficient. There is essentially no vitamin D in the diet. Most people vitamin D comes from sun exposure. If you’re not getting adequate sun exposure you’re at high risk for vitamin D deficiency. You can use the app dminder.info that can provide guidance for sensible sun exposure. Alternatively I give my patients 3000 IUs of vitamin D daily.

    Posted May 13, 2014 at 3:54 pm | Permalink

    Dear Doctor Holick,

    Thank you for your D-lightful expertise on Vitamin D and bringing about great changes in the world view of the importance of sun exposure to human heath and wellbeing.
    Following your advice I had my blood level checked; even though I spend time outside sea swimming and running all year I was supprised to find my D level was quite low. Having had painful acne from my early forties I was pleased to find that after a few months on Vitamin D the pain associated with acne ceased and eruptions were not as severe. It is now two years on and my present blood level is 87ng. Last christmas my wife and I decided to go organic or more precisely eat what is natural in its natural form, so no sugar, cakes, sweets, man made drinks, processed foods, pasta and GM. We only consume organic meat, eggs, cheese, raw milk and vegatables, limiting potatoes and bread to a minimum per week.
    Since christmas the acne has ceased altogether and excess wieght has just dropped off; 30 lbs and still going. We are feeling great, have better looking skin; perhaps strange for a man to say, but true , more bouyant attitudes and more energy.
    Obviously carbohydrate or more accuratly sugar seems to have a detrimental effect on health. As you rightly point out humans evolved in sunshine, and sunshine is an important factor for human health. The diet of evolving mankind would have been very different from todays junk foods and sugar would have been mostly unavailable to them.
    What are your thoughts on a combined approach to improving health through quality sun exposure and a much less refined diet.


    • admin
      Posted July 14, 2014 at 9:51 am | Permalink

      Dear Leonard,

      I agree with you that sensible sun exposure and a more natural diet that is not refined is good for overall health and well-being.

  5. Villy Mitchell
    Posted May 9, 2014 at 3:05 pm | Permalink

    Dear Dr. Holick,

    I would like to ask for some advice, please, and would like to thank you in advance.
    I live in the UK. I recently tested myself and my children for Vit D (25 hydroxy) and the results were:
    me, age 39: 13.5 nmol/L
    my daughter, age 13: 29.3 nmol/L
    my son, age 12: 40.2 mnol/L

    What dosage vit D should I give my children,please, in addition to sun exposure when available in the UK?

    A nutritionist prescribed to me 8000 IU per day plus a multi which gives 800 IU – a total of 8800 IUper day. Would this work ok or would it be best to take the 50000IU per week?
    I have been experiencing various symptoms for the last 4 years, such as back pain, leg pain, pins and needles, palpitations, shaking, constant tiredness, problems swallowing, tightness and pain in the chest and not being able to take a deep breath, brain fog, weakness and generally feeling unwell to do anything but blood tests, ECGs, chest X-rays have not revealed anything and brain and spine scans showed benign tumour on the hearing nerve and osteophytes in cervical spine. The neurologist said that my symptoms are not related to the tumour or osteophytes. My GP never did a vit D test so after research into the possible cause for my symptoms, I did a private test and found out that I was very deficient.

    Could vit D deficiency cause any of the above symptoms or should I continue searching for other causes?

    Thank you very much for your time.
    With best wishes
    Villy Mitchell

    • admin
      Posted July 14, 2014 at 9:48 am | Permalink

      Dear Villy,

      The baseline levels make little difference. I give children 1000 IUs of vitamin D daily and adults 3000 IUs vitamin D daily. Yes vitamin D deficiency can cause aches and pains in the bones and muscles. This is known as osteomalacia. Osteophytes can be caused by many things but usually not vitamin D deficiency.

  6. David S. FootermanMD
    Posted May 2, 2014 at 2:10 pm | Permalink

    Dear Dr. Holick,

    I can review all your literatures and find daily doses ranging from 2,000 IU to 8,000 IU.
    I realize that the issue of daily dosing is a work in progress as you woo the medical community and straighten out the IOM, but it should surely be possible, with a large enough study, to set forth guidelines based on empirical biochemistry. At the moment, it feels to me more like a grand auction, different clinical indications being the works of art, different daily values being the bids, and different physicians and others being the bidders….. “sold to the woman with the wooden leg”.

    David S. Footerman, MD.

    • admin
      Posted July 14, 2014 at 9:37 am | Permalink

      Dear David,

      The Endocrine Society Practice Guidelines does provide physicians with the rationale for how much vitamin D to give to patients. They defined deficiency as a 25-hydroxyvitamin D <20 ng/mL and insufficiency as 21-29 ng/mL and sufficiency as 30-100 ng/mL. From my experience I treat vitamin D deficiency with 50,000 IUs of vitamin D once a week for 8 weeks and then to prevent recurrence I placed him on 50,000 IUs of vitamin D once every 2 weeks forever. We published the paper in Archives of Internal Medicine 2009 demonstrating that this is effective. Obese people with a BMI >30 often need 2-3 times more vitamin D2 to both treat and prevent recurrence of vitamin D deficiency.

  7. David S. FootermanMD
    Posted May 2, 2014 at 1:54 pm | Permalink

    Dear Dr. Holick,

    1. Can you please quantify your definition of vitamin D deficiency versus insufficiency?

    2. I was surprised by the small dose of D – 15mcg/100g of vaseline – that will reduce hyperproliferation in the skin. Have I got it right?

    3. Have you done any controlled quantitative studies showing what different daily doses of D 3 will do to the 25OHD3 level in different cohorts for weight, height and age. I want to get a handle on how much for how long it takes for my patients to get to 30 ng/mL, 60 ng/mL, 100 ng/mL and 150 ng/mL?

    I’m interested in the biological variation for people with a given physiognomy or, more narrowly, for a given height, weight, and age, ignoring all the other variables?

    Thank you so much for your attention.

  8. Mazell Kolvyn
    Posted April 25, 2014 at 11:01 pm | Permalink

    What is your opinion of Vitamin K necessary for Vitamin D absorption?
    Thank you very much.
    I really enjoyed your book and recommend it to everyone I know!
    Regards, In health.

    • admin
      Posted July 14, 2014 at 9:39 am | Permalink

      Dear Mazell,

      There is no evidence to suggest that vitamin K is necessary for vitamin D absorption. This in my opinion is a myth. We have done numerous vitamin D absorption studies and demonstrated that it was being absorbed without the need for anything else including vitamin K.

  9. fabi
    Posted April 25, 2014 at 12:09 pm | Permalink

    Hi. I take one 50000 monthly. (Or maybe 500000 im not sure. Its not written on the box and i cant read the drs handwriting). I take one on 1st of each month. At tje end of the month, around 24th, 25th i start feeling fatigued and sleepy till 7th, 8th of the next month. Is that normal? It happens everymonth and durinv that period i have problem doong my job cause i feel tired during the day. What should i do? Should i ask dr to give me weekly or daily vitamin d supplements?

    • admin
      Posted July 14, 2014 at 9:39 am | Permalink

      Dear Fabi,

      I give my patients 50,000 IUs of vitamin D twice a month. You may want to try this. It’s possible that you are becoming insufficient by the end of the month.

  10. Sara
    Posted April 19, 2014 at 7:15 am | Permalink

    Hello Dr Holick,

    My son has alopecia universalis. He is 12 years old. We feel like we have tried everything, but with no luck. Is there significant evidence of a link between alopecia and vitamin D deficiency? He has been taking vitamin d drops (1000IU x 2 a day) for the past 6-8 weeks, but I’ve only noticed some regrowth in his eyelashes in that time. Ideally, how much vitamin D should he be receiving? Kind regards, Sara.

    • admin
      Posted July 14, 2014 at 9:41 am | Permalink

      Dear Sara,

      Although there is no evidence that vitamin D can treat alopecia universalis it is known that vitamin D can improve immune function and reduce risk for autoimmune diseases. Therefore correcting vitamin D deficiency may be beneficial.

  11. mansi
    Posted April 9, 2014 at 12:26 pm | Permalink

    hello, here i am suffer from 25 oh total vitamin d3 iam suffer from asthma since 7 yrs
    iam 17 yrs girl i wanted to get rid of them help medican are regular

    • admin
      Posted July 14, 2014 at 9:34 am | Permalink

      Dear Mansi,

      Vitamin D will not treat asthma but may help reduce risk for developing it and may help in reducing upper respiratory tract infections that can exacerbate it.

  12. Jeffrey
    Posted April 3, 2014 at 8:18 am | Permalink

    Dr. Dr. Holick,
    People owe you a great debt of gratitude for bringing to “light” (pardon the pun) the importance of vitamin D. Many studies that confirm what you say tend to get glossed over by the mainstream. I suspect when it comes to D, a decade or two from now, doctors will be hitting their heads and saying, “If only we had known!” Dr. Holick knew!

    I do have one question for you though. Do people need to worry about too high a level of oral supplementation to reach a good blood level? I currently take 10,000 IU of a mushroom-based D, and my levels range from the high 30′s ng/dl to 50+ ng/dl, the latter during the summer when I can add some good sun. Is it safe to continue to take 10,000 IU orally? Thanks in advance for your opinion on this!

    • admin
      Posted May 13, 2014 at 2:04 pm | Permalink

      Dear Jeffrey,
      The Endocrine Society recognizes that up to 10,000 IUs daily is safe. The fact that your blood level is in the range of 30-50 ng/ML means that it is fine and there should not be any concern for toxicity.

  13. maria
    Posted April 2, 2014 at 10:22 pm | Permalink

    Dear doctor,
    I had written to you earlier when i was low in vitaminD, which was 13.7 ng/ml. the doctor prescribed vitanova granules 60,000 iu once a week for two months and calcimax forte everyday and wellwoman once a day for two months. After consuming this my vitamin d level rose to 93.8ng/ml and i got severe pain in my left thighs and hands. I went to the orthopeadic doctor who told me to stop all medication which i did for three months and now the severe pain in my left thigh has gone except at times i do feel a tight pulling pain in that thigh. Now my vitamin D level has dropped to 25.3ng/ml and for the last 1 and half week im getting pain in my fingers and in my feet. Is it due to this. Im scared im getting arthritis. How much of the above medicine should i consume to be stable again in vitamin d so it does not go too high or too low. Im now 44 years old and when i was born, my mother told me that i was going in for rickets but the doctors gave me injections and i was okay. I will be grateful if you could advise me. Besides i will be going to my orthopeadic doctor in the next two days. God bless you doctor for helping people like us thankyou.

    • admin
      Posted May 13, 2014 at 2:03 pm | Permalink

      Sometimes patients with chronic vitamin D deficiency can have low discomfort after treatment with vitamin D. I typically keep my patients on 50,000 IUs of vitamin D once every 2 weeks. You should maintain a blood level in the 30-40 ng/ML range. I doubt that the bone pain is a precursor for arthritis.

  14. Posted March 24, 2014 at 6:04 am | Permalink

    „8.000 I.U. of Vitamin D3 as a daily supplementation need 1.000 Mikrograms (=1 mg) of Vitamin K Menachinon-7 (MK-7)” = Statement from Minute 27:30 in Dr. Mercolas Interview with Dr. Kate Rheaume-Bleue – matrix-Gla-protein (MGP)

    = https://www.youtube.com/watch?v=Vbd8FqnVT4c

    Can You recommend a K 2 Supplement.

    • admin
      Posted July 14, 2014 at 9:32 am | Permalink

      Dear Volker,

      In my opinion the utility of vitamin K2 in enhancing bone health is still questionable. However for those who wished to take a vitamin K2 supplement a national brand is usually fine.

  15. Annabel Wheaton
    Posted March 23, 2014 at 11:42 pm | Permalink

    Hi Dr. Holick

    My name is Annabel and I am a year 11 student at Seymour College in Adelaide, Australia. As a part of recieving your HSC here you have to complete a research project on the topic of your choice. I have chosen to do mine on Vitamin D deficiency in Australia and how modern society is contributing to it.
    If you could please contact me, I’d love to ask you some questions and see your thoughts and opinions on the issue.

    Thank you most kindky. I look forward to hearing from you soon

    • admin
      Posted July 14, 2014 at 9:32 am | Permalink

      Dear Annabell,

      I presume you have been to my website DrHolick.com. You’re welcome to contact me at Boston University Medical Center.

  16. Philip Dellin
    Posted March 22, 2014 at 2:16 pm | Permalink

    Dr Holick:

    I have been quite sedentary, not going out much, due to two back surgeries in 2012 and 2013. As I was trying to become more active in January 2014, following my surgical recovery, I noticed that I had neck muscle pain, upper back muscle pain, and then I developed calf and hamstring pain if I tried to walk more than a few hundred yards. I tried two months of PT with no help. Exercise of any kind (lifting groceries, walking ) makes the muscle pain worse.

    My GP checked my CPK – it was normal. He also took me off my statin a month ago as a test (no impact yet). My neurologist did a physical exam and thinks that is not neurological. Two weeks ago my rheumatologist did a complete blood panel – all normal except my Vitamin D was 15 ng/ml. My endocrinologist saw the results and put me on 50,000 IU /wk of D2 a week ago for 8 weeks. I also observed that I do have some bone pain when someone pushes a finger into my upper ribs or tibias.

    Now that the sun is becoming more effective (in NYC) should I try some smart sun exposure also or will that be too much, given the 50,000 unit/wk pill? I have the dminder app.

    Other health websites suggest taking magnesium for muscle health and calcium so that the increasing D can help the calcium be absorbed. Should I also take magnesium and calcium supplements? If so, I assume that the calcium pills should not contain additional Vitamin D. I drink 3 glasses of milk a day.

    If the muscle pain (and mild bone pain) is Vitamin D deficiency related, how soon would it feel better?


    • admin
      Posted July 14, 2014 at 9:29 am | Permalink

      Dear Philip

      If you have a balanced diet especially with green leafy vegetables you should be getting enough magnesium from these dietary sources. You do not need to take magnesium with calcium in order for the calcium to be absorbed. It does not matter if the calcium pill contains vitamin D since the vitamin D has to get activated in the liver and kidneys before it can work on increasing intestinal calcium absorption in the intestine. Drinking 3 glasses of milk a day will supply you with an adequate amount of calcium. That is what I do every day for my calcium requirement.

  17. Mahmood
    Posted March 19, 2014 at 7:30 am | Permalink

    Dear Dr.Holicks,
    I am diagnosed with a vit D deficiency (38 nmol/L, where the hospital ref range= 75-200 nmol/L). Last week i took a 50000 IU D3 tablet and yesterday for my coming week. The DR now has prescribed a 300000 IU injection and asked to stop taking the tablets for a month. I just wanted to confirm that i can go ahead with the injection and no need to worry about the overdose symptoms.

    Also can this low level for a long time has the ability to amplify Knee meniscus tear injuries, and cause Osteoporosis or Arthritis. Thanks a lot and God Bless U for your great work!

    • admin
      Posted May 13, 2014 at 2:07 pm | Permalink

      Dear Mahmood,
      The tablets are fine and should correct your vitamin D deficiency. The 300,000 international units injection is usually only for people who cannot absorb vitamin D because of some type of malabsorption syndrome. It should however not cause toxicity.

  18. Mahmood
    Posted March 19, 2014 at 7:28 am | Permalink

    I am diagnosed with a vit D deficiency (38 nmol/L, where the hospital ref range= 75-200 nmol/L). Last week i took a 50000 IU D3 tablet and yesterday for my coming week. The DR now has prescribed a 300000 IU injection and asked to stop taking the tablets for a month. I just wanted to confirm that i can go ahead with the injection and no need to worry about the overdose symptoms.

    Also can this low level for a long time has the ability to amplify Knee meniscus tear injuries, and cause Osteoporosis or Arthritis. Thanks a lot and God Bless U for your great work!

    • admin
      Posted July 14, 2014 at 9:29 am | Permalink

      Dear Mahmood,

      The 300,000 IUs injection should be fine even if you took a 50,000 international units dose of vitamin D. This should not cause toxicity. There is no evidence that vitamin D deficiency will cause arthritis but it can exacerbate and precipitate osteoporosis.

  19. melissa Gonzalez
    Posted March 18, 2014 at 11:11 pm | Permalink

    I took three doses of 50000 once a week, but got sick how long will it take before its out of my body?

    • admin
      Posted July 14, 2014 at 9:28 am | Permalink

      Dear Melissa,

      The half-life for vitamin D is about 24 hours so it should be gone within a few weeks. It’s possible that you are allergic to one of the ingredients in the supplement. Alternatively I have my patients take 2000 IUs of vitamin D3 daily.

  20. Stephen Rudyk
    Posted March 18, 2014 at 1:25 pm | Permalink

    Hello. Thank you for all your work over the years on Vitamin D. You have been alighthouse for many of us in an ocean of darkness. Thank you!
    My question is related to Vitamin D3 intake and Vitamin K2 (Mk-4 or Mk-7). Many are advocating that K2 be taken along with Vitamin D3. In fact some have even suggested the following: Rheume-Bleue suggests that for every 1,000 IU’s of vitamin D you take, you may benefit from about 100 micrograms of K2, and perhaps as much as 150-200 micrograms (mcg). It goes on to say that not doing so would cause calcification of the arteries of the heart. Is this true? Or is this simply another outrageousstatement? I am concerned because there have been reports indicating that MK-4 and MK-7 have caused arrhythmias in some people, although I have no science to back it up. Can an adult safely take 4000 IU of D3 indefinately without taking K2? Do you recommend any compliment supplements to ne taken with D3?
    Thank you for your time.

    • admin
      Posted May 13, 2014 at 2:07 pm | Permalink

      Dear Steven,
      The vitamin K2 -story is still open to question. I typically have my patients on 3000 IUs of vitamin D daily without taking vitamin K2. I take 4000 IUs of vitamin D daily without vitamin K2.

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