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Vitamin D dosing is very personal:

Each person has their own personal dose of vitamin D that must be learned by testing the D blood level. An example: A mother is dosing three of her kids with 2,000 IU/day for one month in the winter, Nathan goes from 20 ng/ml to 50 ng/ml, Samantha goes from 18ng/ml to 25ng/ml and Alex goes from 25ng/ml to 95 ng/ml, each are taking exactly the same dose for same period of time.

The maximal amount of vitamin D made on the skin of a light skinned person, fully sun exposed, middle of the summer, is said to be 20,000 IU, so that is the largest dose that I will start even in someone whose level is very low (undetectable –10ng/ml). That does not mean that everyone gets into the right range with that dose, however. Some of my patients required much bigger doses, up to 50,000 IU (D3 not D2) per day for several years. They had usually been very sick for a very long time and we worked up to that dose over many months as their D level failed to increase on lower doses. Though it is documented that there are people who have specific problems with absorption, I have tried various types of replacement in those who needed larger doses: on the skin, sublingual etc, and I did not find that those methods were any more reliable than oral pills.

I disagree with the proposed idea that fat people have lower D blood levels because they’re fat. It has been suggested that they dilute their vitamin D by storing it in their fat, instead of their blood. Obese people may indeed have lower D levels, and require higher doses, but I think that is because they have been sick longer. Their low D level caused their obesity, not the reverse. 5-6 years of dosing the same obese person also revealed that the dose requirements fell over time, into a more routine range, even while the weight remained the same.

There are several other variables that affect vitamin D blood dosing. Based on my experience with over 5000 patients, about one in 50 people needs much smaller doses. These people operate in a dose range of 1/10th of what everyone else needs. (This probably suggests that they also make less vitamin D per sun exposure, though that has yet to be proven.) It is also impossible to predict who will need these smaller doses; they can have any initial D blood level, can be any color and any age. If you are one of these few you will feel terrible within a week of starting a D dose that is ten times too big, and this is one of the reasons I suggest that you start slowly.

I did not attempt to measure any of the genetic mutations that affect skin production of vitamin D, vitamin D binding protein, GI absorption, or the vitamin D receptor. These are all variables that do indeed exist and need to be sorted out once the “healthy” D level is actually agreed upon. Until then I don’t think it makes sense to blame all differences in D dosing and blood levels on “problems with absorption”. What I learned over time was that if the level wasn’t going up usually the dose being given was just too low. Please see the chapter on “Vitamin D Controversies” for more details.


  1. Chris R

    I have sleep apnea and find your site very interesting. I failed on CPAP therapy but use an oral device every night. I have tried several brands of vitamin D but each vitamin D gives me a severe headache. I have never been able to take it more than 2 or 3 days. Any thoughts on why this would be? I’m a landscaper so I get tons of sunlight in the summer. My doctor was at a total loss why my D levels would be in the 20s. And clueless as to why vitamin D would give me a severe headache.

    • Dr. Stasha Gominak

      Dear Chris: Two possibilities on why you have a headache in response to D One: your level is very low but you only need a very small doseand the dose you’re taking though small is still too big for you. Usually those people complain of feeling generally horrible but not specifically of headache.
      The second and most likely reason is that you are not just D deficient, you are also magnesium deficient. If you’ll read further on my site I explain why you are also very deficient in several B vitamins and minerals that are either made by the intestinal bacteria or are helped in their absorption by those same bacteria. The way around it is usually to supplement magnesium, in the form of sunflower seeds, 1/4 C. per day or any magnesium pill except magnesium oxide, usually about 500 mg/day. If you read further on my site you will also see that you need to check your B12 and to start on B50 as well. Hope you get better!

    • Dr. Stasha Gominak

      Please read further on the site. D is managed by blood level not by dose. There’s a lot to learn about how to use D and this site is dedicated to teaching you about that complexity.

    • Dr. Stasha Gominak

      I don’t think it matters. Logically we would receive it during mid day from the sun.

  2. Alison

    Hi – our dentist recommended that we check out your work as my 13 YO daughter’s sleep study showed almost no REM (although her growth has been normal so I guess she’s been getting some over the years). Her D3 levels were very, very low but her B12 levels were fine BUT I also know she has methylation issues so am concerned about taking regular B12 (in B25 or B50 pills) as opposed to methyl B12 or is that a completely different issue and we should just start with the B25 along with Vit. D3? I haven’t seen any discussion of methylation – not sure if the B12 used as part of the sleep process is a completely different process than what happens as part of the methylation process. Thank you so much for your work – I’ve been telling everyone about it!! I

    • Dr. Stasha Gominak

      Hi Alison:
      My clients who have been tested have chosen a B complex that is compatible with what they’ve been told by the caregiver who did the methylation testing. You are correct that B12 is not an issue for your daughter if her level was >500, but at thirteen she should use the full dose B50 not B25. It will not hurt her in any way to buy a regular B50 that does not have the metylated B12.


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