VDC test kit slider
VDC test kit slider
sperti logo 1
Text size A A A
High contrast on off

Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

New review covers some of the biggest questions in vitamin D

Dr. Arash Hossein-Nezhad, currently a scholar at Boston University has teamed up with senior author Professor Michael Holick to write a spectacular in depth review about vitamin D for the highly respected journal, Mayo Clinic Proceedings.

Hossein-Nezhad A, Holick MF. Vitamin d for health: a global perspective. Mayo Clin Proc. 2013 Jul;88(7):720-55.

The publication covers so many things we currently know about vitamin D, it makes a compelling case for a spectacular role of vitamin D in human health. Here were some highlights and questions answered:

Can vitamin D be washed off the skin?

I have speculated on this before, raising the question that maybe vitamin D can be washed off. The authors say, no it can’t.

Approximately 65% of the vitamin D precursor, 7-dehydro-cholesterol, is found in the epidermis. More than 95% of the pre-vitamin D3 that is produced is in the living cells of the epidermis (underneath the hard cornified outer layer) and thus cannot be removed from the skin by washing.

This explains a forgotten 1937 paper (Helmer AC, Jensen CH: Vitamin D precursors removed from the skin by washing. Studies Inst Divi Thomae 1937, 1:207-216.) in which the authors proved that irradiated surface skin oils (sebum) of young men cured rickets in animals and that vitamin D containing sebum was removed by washing. It is probably the 5% of vitamin D made on the surface of the skin that is removed by washing.

Is there a difference between vitamin D derived from sun exposure and from food/supplements?

Ingested vitamin D appears to differ from sun-derived vitamin D only in the fact that ingested vitamin D is first transported away from the gut by chylomicrons before it binds to D binding protein in the lymphatic system.

Otherwise, vitamin D3 is vitamin D3, no matter if it’s coming from your skin or oral intake.

How does vitamin D work during pregnancy?

25(OH)D is transferred across the placenta; fetal cord blood concentration of 25(OH)D is correlated with the mother’s 25(OH)D concentration. However, the active metabolite 1,25(OH)2D does not readily cross the placenta, despite the mother having up to a fourfold increase in her serum 1,25(OH)2D levels.

The fetal kidneys and the placenta provide the fetal circulation with 1,25(OH)2D. This apparently occurs early in gestation, meaning the fetus can activate its own vitamin D.

Epidemiologic evidence has suggested a link between fetal life events and susceptibility to disease in later adult life. This paradigm, referred to as fetal programming, may have a profound effect on public health strategies for the prevention of many illnesses in later life. This may mean that if you were vitamin D deficient as a fetus, taking vitamin in later adult life may not fully protect you from these illnesses.

Can vitamin D help with autoimmune diseases?

Epidemiologic, genetic, and basic science studies indicate a potential role of vitamin D in the pathogenesis of certain systemic and organ specific autoimmune diseases, such as type 1 diabetes mellitus, multiple sclerosis (MS), rheumatoid arthritis (RA), and Crohn’s disease.

Vitamin D suppresses autoimmune disease pathology by regulating the differentiation and activity of CD4+ T cells, resulting in a more balanced TH1/TH2 response that favors less development of self-reactive T cells and less autoimmunity, by increasing the number of T-regulatory cells. This gives hope to the idea that adequate, perhaps pharmacological, doses of vitamin D may have a treatment effect in ongoing inflammatory autoimmune disorders.

The authors point out that treatment of active RA with a high-dose vitamin D3 analogue resulted in improvement of symptoms of RA in 89% of patients, with 45% of patients entertaining a complete remission.

Whether supplemental vitamin D3 can effectively treat active MS is still a matter of debate. In a trial in active MS using escalating doses up to 40,000 IU/d of vitamin D3 for 28 weeks followed by 10,000 IU/d for 12 weeks, there were no significant adverse events, and there seemed to be significantly less progression of disability in the treatment group.

Do genetics influence vitamin D levels?

The genetic contributions to circulating 25(OH)D represent a complex trait for which family studies have estimated heritability ranging from 43% to 80%.

On rare occasions, some patients who deny taking a vitamin D supplement have unexplained high normal 25(OH)D levels in the range of 40 to 80 ng/mL. It is believed that this is due to a genetic mutation of enzyme that breaks down 25(OH)D.

What effect can sun exposure have on mortality?

The authors point out that it was estimated that if all the people in the United States were to double their sun exposure, the net result could be up to 400,000 reduced deaths compared with only 11,000 increased deaths from melanoma and other skin cancer.

Board member Dr Bill Grant calculated that in a span of 24 years (1970-1994), 566,400 Americans died of cancer because of inadequate exposure to solar UV-B radiation.

The paper is free to read in its entirety, and I recommend doing so.

  About: John Cannell, MD

Dr. John Cannell is founder of the Vitamin D Council. He has written many peer-reviewed papers on vitamin D and speaks frequently across the United States on the subject. Dr. Cannell holds an M.D. and has served the medical field as a general practitioner, emergency physician, and psychiatrist.
This entry was posted in Blog. Bookmark the permalink.

9 Responses to New review covers some of the biggest questions in vitamin D

  1. fredglass says:

    Re: Difference between sun exposure & Vit. D supplements/food.

    My experience with approximately 3 to 4 days of 1 hour full body exposure per week and 5K i.u./day reveals a distinct difference. When I feel a cold/flue coming on one or two extra doses of 10K Vit.D3 will always abort any illness. Getting extra sun exposure doesn’t do the trick.

    My reasoning is that since all or most physiological pathways are very complex there are bound to be differences in the amounts & types of vitamin D which arrive at their usable destinations.
    Fred Glass

  2. samueledelstein says:

    Oral intake of vitamin D is associated with atherosclerosis! Oral intake of vitamin D may cause intoxicaion! Mother nature wanted us to get the vitamin from sun exposure. One may stay nacked 1 month in the sun and will not get vitamin D intoxication!!! Anyone who think differently does not really understand the physiology of vitamin D!!!!!!

  3. fredglass says:

    Samuel Edelstein, your comments are too dogmatic for any reasonable response.

  4. anniecmars@yahoo.com.au says:

    While I agree with Samuel (above) that sun exposure is great, it is not always possible to obtain adequate sun exposure. For example, those living in latitudes further away from the equator cannot obtain enough UVB all year round to maintain adequate serum levels throughout the year. People required to working or studying inside during the day have limited time in the sun – including young children who are required to cover up when they go outside at schools in Australia! For most people, it is far more difficult to take too much oral vitamin D than we have been led to believe – toxic levels appear to be rare in those supplementing orally and there is more of a problem with inadequate supplementation which does not raise serum levels to a replete level. Would like to hear the association between atherosclerosis and oral intake of oral vitamin D – can you provide more information on that please? References to scientific studies would be great.

  5. Rita and Misty says:

    Salutations and greetings,

    Regarding oral supplementation of D, daily dosage is secondary to vitamin D blood serum level. In other words, the only thing that matters is your 25(OH)D level, and you need to take whatever daily dose gets you to between 50 ng/ml–80 ng/ml.

    BTW–Here is an interesting j.a. “Vitamin D deficiency is associated with subclinical carotid atherosclerosis: the Northern Manhattan Study” (if you want healthy arteries, make certain you have an optimal vitamin D blood level)

    Regarding sunshine–it is SO necessary and for so much more than vitamin D production. For example, sunshine increases melatonin and serotonin levels, among other benefits. Please do read the below article on Sunshine. It is my all time favorite.

    BTW–Once your 25(OH)D level is raised to optimal, you won’t burn…you just won’t. And, I have a theory that it is only when your body has an optimal vitamin D blood serum level that it may utilize sunshine for its other multitude of benefits. So, I suggest supplementing to an optimal level, and sunning yourself as well, and appropriately.

    I am happy to share the following. I aim to keep my 25(OH)D level at the higher end of optimal. I rarely get sick. On the rare occasion when I do get sick, I take 50,000 to 100,000 iu D3 for 3 days (did anyone faint?). I immediately get better. Always.

    Oral supplementation helps my mood, BUT not as much as sunshine. Sunning myself perks me up. Always.

    Be well,

  6. Michael says:

    Hello all,

    Well, here in Seattle the sun is glorious all summer and absent almost all winter, plus we are are at a higher latitude than Montreal Canada.

    I purposefully sit in the noon day sun at least once a week all summer for 1/2 hour each side and also walk shirtless in shorts at least 4 time a week in less-than-noon-time sun.

    Yes, I have champion freckles, but I am not very tanned or brown.

    When I bathe daily I usually just rinse with plain water. Every two weeks give myself a real scrub-down with a rough towel. What a difference! The rough towel rubs off almost all my “tan” including also diminishing the freckle intensity.

    We are now on a soap free bathing jag, for science. I used to go soap free when younger for convenience and also a little bit because of the idea that “only very modern man uses soap”. You know, in the vein that “only modern man eats processed food, eats/drinks chemicals concoctions that have flavor or color, has epidurals, nose jobs, etc” It gives me direct insight into the natural “tanning” process cycle.


  7. Stan says:

    With natural Synthesis from the sun you not only get all the biological benefits as with the ingested form their is at least 12 of these biological benefits missing.
    One of the crucial benefits is the nitric oxide from sunshine which not many people seem to realise the importance of this.I have used sunbeds for 31 years now and i am very fit and still visit the gym each day,practice martial arts in the evening. Not bad for a 60 year old who trains with teenagers.I am never ill and never been of work.I put a lot of this down to my life style and the 25Ohd reading of mine being 99ng/ml. I also take 5,000iu daily to elevate my serum levels to this figure.

  8. allometric24 says:

    In my opinion high intake of vit D 3 might enhance absorption of calcium which has been shown in some studies to increase CVD risk. It also seems probable that this likely increased risk could be entirely mitigated by adequate intake of Vit K2 (MK-7), a component not easy to obtain in the usual Western diet.
    Have a look at http://www.vitamink2.org – or just take 200 mcg of MK-7 daily.