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 8th video in a nine day series on vitamin D. Be sure to check out yesterday's video-of-the-dayHow the Institute of Medicine arrived at their vitamin D recommendation.

For some context, please check out my associated blog posts: Vitamin D: Shedding some light on the new recommendationsEating To Extend Our Lifespan, 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 8th video in a nine day series on vitamin D. Be sure to check out yesterday’s video-of-the-day How the Institute of Medicine arrived at their vitamin D recommendation.

  • dgmusselman

    Thanks for the comprehensive info. re: vit. D. I’m still unsure, however, about which form of D supplement is effective–D3(nonvegan) or D2(vegan). I’ve even seen ads for vegan D3. Over the last 3 years I’ve seen conflicting reports about the effectiveness of D2? Can you clarify?

    • Michael Greger M.D.

      Taken daily in doses at 2000IU or less, vitamin D2 (ergocalciferol) and D3 (cholecalciferol) appear bioequivalent (meaning they both work just as well in your body). However if your physician suggests you take large intermittent doses (such as 50,000IU weekly, then D3 is probably superior).

      • Toxins

        I take 2400 daily, is this too much?

        • Michael Greger M.D.

          Nope, the current upper daily limit is 4,000 (though more likely 10,000).

          • Cyclo Uten Etternavn

            I’ve found a affordable supplement, however the dosage is 5000 IU per capsule. Would you consider this as too much, Michael? 

          • DrDons

            If you decide you should take a supplement remember that Vitamin D is stored so if you were to take your 5000 IU every other day you would average 2500/d. I think caution is in order especially with supplements which can be toxic. Also cautionary is the study showing that taking isolated supplements Beta Carotene, Vitamin A & E lead to increase morbiditiy and mortality see The best recommendation is to get your Vitamin D from sunlight. It would not surprise me if future studies show that there are other factors that our bodies make with exposure to sunlight that are helpful… time will tell. So I would recommend factoring in your location and amount of sun exposure you get to your decision whether to take supplements and how much to take see Keep tuned as new scientific studies shed light on these complex issues.


    Thanks for the awesome website!
    So I’m assuming that the suggestion of 2000 IUs/d to hit the “sweet spot” are the total IUs of vitamin D/d, meaning from all sources such as supplements, food, and sun. Is there a correction factor to apply to 2000 IU/d to account for sun at various latitudes and times of the year? (For example, Denver, CO — Summer versus Winter.)


      So I watched the videos in reverse order a saw that there’s no “one-size-fits-all” correction factor. Guess I’ll just shoot for 2000 IU/d in the Winter and less if I’m getting some sun.

  • JoyZakarian

    Hi Dr. Greger,

    Is the 2,000 IU/day recommendation the same for vegan Vitamin D2? I thought one of your articles in a previous video explained that they aren’t exactly equivalent. Thank you!

    • Michael Greger M.D.

      Same recommendation Joy–see my response to dgmusselman above.

  • dave23

    Thanks for the this informative video. Aren’t there other health benefits from the sun that we can’t get from supplements?

    Also, if I live on the east coast and get pretty much zero sun during the winter should I just take vitamin d or should I get tested because perhaps I have enough stored from previous sun and/ or from mushrooms?

  • Michael Greger M.D.

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

  • Sheri O

    Are your recommended levels the same for children as they are for adults?  

    • beccadoggie10

      I’ve read that adult dosages given to children are toxic. Any comment on this?

      I’m worried about the source of vitamin D3 CHOLECALCIFEROL, coming from cod liver oil or the liver of other fish. That also depends upon the waters from where those fish live, but all waters are increasingly toxic with chlorinated pesticides, PCBs, Dioxins. Don’t those also contaminate the liver?

      I would feel more comfortable about a vegan vitamin D2 supplement, but my local health food store only carries vitamin D3 from cod liver oils. I desperately need vitamin D to keep my bones strong especially with osteoporosis but need a brand name for security.

  • Marek Záda

    I have read a number of articles on vitamin D and dundruff. I suffer from dundruff for over 10 years, no shampoo really cured my scalp. However, when I go for vacation – usually nearby sea during summer time, dandruff almost disappears within a week. I never thought of vit. D deficiency as I never had a broken bone (yet live an active lifestyle). I live in central Europe and am an office rat, lack of sun exposure is quite common in my case. I concluded that a weekly safe tube tanning might be a good way how to get D3 they way we are supposed to. Your opinion on the matter?

  • Julia

    I just discovered that Magnesium supplement helps/cures not only my newly revived muscle cramps, but also longstanding insomnia. Foot cramps (usually at night) arose after taking 2000IU/d Vitamin D for a few weeks. I read a story about a woman whose serum D levels didn’t go up with supplementation until she also took magnesium. Apparently it takes a good bit of Mg to convert the D to its usable form. Did any of the research on optimal D supplementation levels take Mg levels or intake into account? BTW, I’ve been eating nutrient dense whole plant food, lots of greens, for going on 6 years. Still I noticed if I skipped more than a day or two eating spinach, I’d get the leg and toe cramps. Wondering if i need less D when i get enough Mg. I am 61y.o. female. Thanks!

  • Celia Ready

    Hi Dr Greger please answer my question. ???? Last year I had 1/2 my thyroid removed due to a undiagnosed nodule, which was benign. So I could have left it there. Very frustrated about that. Seeing my parathyroid glands have been interferred with during the operation and always keeping a check on my thyroid levels, due to having OSTEOPENIA, degenerative discs in my cervical spine. I would like to know which is the best way to avoid more bone loss seeing I am only 49. Should I eat more mushrooms and magnesium rich food. Is it only certain mushroom that have a high level of vitamin D OR do all mushrooms have vitamin D. Should I be taking vitamin D and magnesium supplements and vitamin K supplements and BORON supplements, Because don’t you need all of those vitamins working together to absorb enough calcium for your bones and other organs to keep healthy. Please explain. Should you be getting more vitamins from eating real food, or topping up on supplements. I would like to be able to educate my children as well. So this would really be appreciated. Advice from you.

  • Celia Ready

    I will be having more surgery shortly a hysterectomy so more recuperating, not a lot of exercise happening for a few weeks after that operation. So not much sun around during winter. So do you take supps or not.???

  • Noboa

    can I take vitamin D 50,000 IU D2 one time a week along with my reg dosis of Donepezil 5 mg

  • Anna Kathrine Fløistad

    Thank you. I am a woman (from Norway) with ms- and are quite confused of how high level of D vitamin I should have and the best way to take it. There are not much sun here in Norway. At the same time, it could reduce attacks, so I’ve heard. I am confused, because there are several ways of measure the vit D level.. Is solarium the best mean or should one take substitudes? And are there other factors that lowen the leven of vit D? f.ex in food etc.

    • JacquieRN

      Hi Anna, you may want to check out all the other videos on Vit D:

    • Dr Colin Walsh

      Hi Anna – even more important than vitamin D is eating the right kind of diet. An American neurologist called Swank used a very low fat diet for recently-diagnosed cases of MS and got excellent results which were published in the Lancet around 1990. A 30 year follow-up revealed that all his patients who stayed on the diet were alive and well, with little or no disability. Another study is being done at the centre where Swank worked (Oregon USA), with Dr John McDougall acting as the advisor on diet. See the Dr McDougall website By the way, Dr McDougall is happy to answer emails. Good luck. Dr Colin Walsh

  • techomaniac

    why not just take 60,000 once every month since the body regulated the mega dose down to that sweet spot level?

  • Beate

    My husband had 4stage liver cancer 2 years ago. He is healing himself with nutrition supplements and cannabis oil. My question is, his vitamin D3 levels have been way to low, around 27. He is taking daily 10000 D3 in liquid form. He feels healthy, gets plenty of sunshine also. Why aren’t his levels coming up? His cancer shrunk 2/3 and tumor markers are normal

    • Lokesh Soni

      Hi Beate. This is a remarkable comment to read. I wonder if there is any chance i could speak with you by phone / email? I have family who is treating their tumor naturally and would love to be able to speak with you if possible. I can be reached on or +34 674552214(Spain). Thanks, Lokesh

    • dogulas

      Way low? 27 is pretty close to the supposed ideal of about 30 ng/ml. He’s healthy, and he should be. Why try to assume his body needs to be in a place it is apparently fighting hard to stay at? The body knows what it needs, and his needs what everyone else’s does: around 30 ng/ml. I bet if he tested again it wouldn’t be 27, it would be different. Levels fluctuate.

  • Edith

    Dr. Greger, my (young) doctor has just given me a prescription for Ergocalciferol 50000 Unit Oral Capsule (**8** Capsule) to take one/week for eight week and then retest. I have sarcoidosis (currently no symptoms) and have been told in the past not to take Vitamin D supplements. I’ve just moved to Florida from Michigan. Blood test results were 26 ng/mL. Do you consider this a reasonable course of action?
    By the way, Sunday cup of tea is always enjoyed reading your email.

    • Nicole Jaja

      My mom has sarcoidosis too. So if i understand your post correctly, vitamin D supplementation is not advised for people with sarcoidosis? And if i could ask, how are your vit.D levels now and do you still supplement with 50000 IU?

      • Edith Andersen

        The last blood test shows it to be normal. I took the supplement for one week.

        • Joseph Gonzales R.D.

          Glad to hear numbers improved! I suggest more Florida sun :-) and continuing having levels checked by your doctor.

  • davidbala

    I have read recommendations that all of us–whether one is diabetic/pre-diabetic or not–would benefit from taking Metformin. Life Extension has been recommending it for 20 years. Metformin is the only drug they recommend. It appears to have positive impacts on cell function and longevity, decreasing cancer rates and increasing cellular metabolism, specifically by increasing the production of AMPK. I am interested in your perspective of Metformin use for non-diabetics.

  • Joe Tilman

    Are there any studies regarding eczema and vitamin D? Looking at medically prescribed eczema treatments such as UV treatments, and anecdotal evidence regarding vitamin D, it seems like a promising path…from a layperson’s viewpoint. Would love to see if there is anything more than anecdotal evidence.

    • Don Forrester MD

      A quick PubMed search showed a number of articles but at this point it doesn’t appear to be a relationship between eczema and Vitamin D. There is evidence to support treating Eczema with diet see… Of course keep tuned as you never know when some new science will help shed light on the best lifestyle especially nutritional approaches to patients suffering from eczema.

  • dogulas

    If a human living far enough away from the equator supposedly cannot expose themselves to enough sunlight during certain months of the winter to sufficiently make vitamin D naturally, how is it that they can still get a sunburn during those winter months?

    • Don Forrester MD

      As we moved away from the equator we tended to lose our pigment to allow for more production of Vitamin D and the other beneficial aspects of sun exposure. Losing our pigment, however, makes us more susceptible to sun damage so we have to be careful not to get too much exposure.

      • dogulas

        Thank you!

        I found some more helpful information elsewhere that explains the paradox as well: Vitamin D synthesis is enabled by UVB absorption, which the atmosphere scatters more. Sunburns are mostly from UVA, which the atmosphere doesn’t scatter much, even at the north pole.So even a sunburn doesn’t mean getting enough UVB in winter months at certain distances from the equator.

        • Don Forrester MD

          Good point. Thanks. Interestingly the UVA seems to be responsible for liberating nitrate like compounds into our blood and helping our arterial system.

  • C Hamel

    Is the 2000 U/day recommendation based on an oral or sublingual dose?

    • C Hamel

      Ooops! I meant to ask this question under a Vit B12 thread (@ 2.5 mg/wk).

      • Don Forrester MD -NF Volunteer

        It is recommended as sublingual but oral would most likely work as well. The Vitamin B12 needs to be absorbed in the upper part of your GI tract. Be well.

  • nicolasmainella

    I’m only able to find 10.000 IU capsules where i live, is it ok for me to consume this dosage every 5 days, reaching this way the 2.000 IU sweet spot?

    • Joseph Gonzales R.D.

      Hi Nicolasmainella, I think there are too many factors to say for certain. (age, skin color, dietary Vit. D intake, location, etc) I would ask your doctor the best dosage for vitamin D supplementation right for you. As I understand it needs are very personalized. Quick thought can you order lower doses of Vitamin D online?

      Best to you,

      • nicolasmainella

        Ok, thanks i’ll check it with my doctor!

  • Carlee

    Dr. Greger, I’m a mom of two little ones under 3, and am having a really hard time losing ANY weight (I still have about 10 pounds from my first baby to lose, and about 20 additional to go to my optimal weight). I have been on a diet and exercise program for the last 6 weeks, and have not lost a single pound; in fact, the scale is going UP! I’ve read that Vitamin D can help with weight loss, but I’m also wondering how hormone levels affect weight loss. From what I can find, there is very little information about mothers and weight loss, except the old “It takes 9 months to put it on, give your body time, bla bla bla.” I can’t be the only mother who can’t get rid of this belly! Any insights would help!