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Posted by mfholick on November 26, 2008 under Vitamin D | 26 Comments to Read

Vitamin D is Called the Sunshine Vitamin for Good Reason

Michael F. Holick, PhD, MD
Professor of Medicine, Physiology and Biophysics
Director of the General Clinical Research Center
Director of the Vitamin D, Skin and Bone Research Laboratory
Director, Biologic Effects of Light Research Center
Boston University Medical Center

Vitamin D is not a vitamin but a hormone. It is unique in that it is made in the skin as a result of exposure to sunlight. Photosynthesis of vitamin D has been occurring on earth for more than 750 million years. Some of the earliest life forms that were exposed to sunlight for their energy requirement were also photosynthesizing vitamin D. Both children and adults have in the past depended on adequate sun exposure to satisfy their vitamin D requirement. It is well documented that at the turn of the last century upwards of 80% of children in the industrialized, polluted cities of northern Europe and northeastern United States suffered from the devastating consequences of vitamin D deficiency rickets. The skin has a large capacity to make vitamin D. Exposure of a person in a bathing suit to a minimal erythemal dose of sunlight, which is typically no more than 15-20 minutes on Cape Cod in June or July at noon time, is the equivalent to taking 20,000 IU of vitamin D orally. It is now well documented that in the absence of any sun exposure 1,000 IU of vitamin D3 a day is necessary to maintain healthy levels of 25-hydroxyvitamin D in the circulation. An analysis of the NHANES III data has demonstrated that neither children nor adults are receiving an adequate amount of vitamin D from their diet or from supplements.

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Figure 1: The causes and consequeces of vitamin D deficiency (click the image for a larger version)

Is there any advantage to being exposed to sunlight to produce vitamin D rather than taking a pill that contains an adequate amount, i.e., 1,000 IU of vitamin D3 It is known that when exposed to sunlight the vitamin D that’s made in the skin enters the dermal capillary bed, and essentially 100% is bound to the vitamin D binding protein. When vitamin D is ingested, it is incorporated into the chylomicrons and is transported through the lymphatic system, which in turn, is deposited into the venous system where it eventually is metabolized in the liver to 25-hydroxyvitamin D. As a result, no more than 60% of the vitamin D that is ingested is bound to the vitamin D binding protein, whereas the other 40% is mostly bound to lipoproteins. Thus, the vitamin D that is made in the skin has a longer half-life in the circulation than it does when ingested from the diet or from a supplement. Furthermore, the vitamin D produced in the skin from sun exposure is free, unlike a vitamin D supplement. You can never become vitamin D intoxicated from sun exposure, but you can if you take too many vitamin D pills.

90-95% of most people’s vitamin D requirement comes from casual exposure to sunlight. Why is there such a controversy about sensible sun exposure as a recommendation to satisfy our vitamin D requirement? The sun has been demonized, and as a result, most of the world’s population has been brain washed into thinking that any exposure to sunlight is bad medicine. This is unfortunate since there is essentially no substantiated scientific evidence to suggest that moderate sun exposure either significantly increase risks of squamous and basal cell carcinomas, and more importantly, the most deadly form of skin cancer melanoma. There is no question that excessive exposure to sunlight and sun burning experiences significantly increase risk of both basal and squamous cell carcinoma. However, these cancers are often easily detected, and if detected early, are easily treated and often cured. Melanoma on the other hand, is a very aggressive and deadly form of skin cancer. However, most melanomas occur on the least sun exposed areas, and a recent meta-analysis of 35 studies suggests that occupational exposure to sunlight decreases risk of developing melanoma.

Why not take advantage of sensible sun exposure? Not only do people feel better but they also will obtain their vitamin D requirement during the spring, summer and fall. It is possible to maintain adequate vitamin D stores by taking an adequate amount of vitamin D from a supplement. It is extremely unlikely that a person can get an adequate amount of vitamin D from their diet, however. The major issue of obtaining vitamin D from a pill is that the person has to remember to take the pill, and they have to be able to find a pill that contains the needed amount of vitamin D, i.e., 1,000 IU of vitamin D3.

There needs to be a reevaluation of the important role that sensible sun exposure has in providing vitamin D for the world’s population. Indeed, in Australia and New Zealand where the incidence of skin cancer are the highest in the world, the New Zealand Bone and Mineral Society in collaboration with the Australian College of Dermatologists and Cancer Council of Australia have recommended that a balance is required between avoiding an increased risk of skin cancer and achieving enough UV radiation to maintain adequate vitamin D levels. I believe Charles Shultz said it the best in his Peanuts comic strip where Linus is sitting in the school yard, opens his lunch to find a note from his mother encouraging him to “make good friends, get good grades”, and she notes, “I hope that you are sitting in the sun, for a little sun is good as long as we don’t over do it. Perhaps 10 minutes a day this time of the year is about right.” He was right on target. Hopefully this message will be heard, and this recommendation will be adopted world-wide.

References:

Holick, M.F. Vitamin D: Importance in the prevention of cancers, type 1 diabetes, heart disease. and osteoporosis. Am J Clin Nutr 2004; 79:362-371.

Holick, M.F. Resurrection of vitamin D deficiency and rickets. J Clin Invest 2006, 116(8):2062-2072.

Holick, MF. Vitamin D Deficiency. N Engl J Med 2007;357:266-281.

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  • Judy Converse MPH, RD, LD said,

    I provide nutrition assessment, care, and monitoring for children with developmental and learning disabilities – a population usually overlooked for nutrition concerns. Between their poorer food intakes, intestinal infections, and frequent malabsorption issues, they must surely have poor D status – I’d wager, worse than the already questionable D status of typical peers. Nutrition deficits in autism have emerged in the literature already for other nutrients like calcium, zinc, or iron. Fascinating topic, and the 3 hour lecture I attended by Dr Holick never once became dull.

  • Karen Neil said,

    The lecture on Vitamin D was very interesting. Why is it that doctors do not evaluate for proper levels in patients? It seems to me that they could diagnose many of the problems that patients complain of, by this blood test. How come the doctors aren’t doing this?

  • Evelyne Tourigny said,

    I think the major issue of obtaining vitamin D from a pill such as 1,000 IU of vitamin D3 is that a person can elevate his D125.
    Dr Holick do you think that too much D3 can be dangerouse? Why The FDA only allows D2 for treatment???

  • Carolyn Hudson, RD, LD said,

    Any chance we can get the Dec 10/2008 Webinar put back on this site? I continually have people ask me about it and would like to direct them to it again.
    Thank you so much!
    Carolyn Hudson, RD, LD
    Midwest Dariy Association
    2015 Rice Street
    St. Paul, MN 55113
    1-800-406-MILK (6455)

  • GEORGE MANDLER said,

    Dear Dr Holick,
    At the Integrative Healthcare symposium in NYC you spoke that breast milk is deficient in vitamin D and giving vitamin D to the mother does not help the baby.
    Can you please point me to your research showing the if a mom is replete in Vitamin D then her breast milk is still deficient.

    There are several published studies from Hollis and Wagner from U of SC that show breast milk 25(OH)D levels correlate well with plasma 25(OH)D levels. Here is one:
    Am J Clin Nutr. 2004 Dec ;80 (6 Suppl):1752S-8S Pub Med ID: 15585800

    thank you
    George Mandler

  • mary mcdarby said,

    my blood tests showed my vitamin D to be well over the established limits.(I think about a 40); But I did have elevated para-thyroid hormone. The 24 hour urine test proved to be normal. However, I was advised to take more vitamin d. I now take a 1000mg daily supplement in addition to the additive in my calcium supplement (2/day) and the vitamin d in my multiple vitamin. In addition, although I live in the Northeast, I am outside whenever I can be (daily from April to October about 5 hours). Can you overdose on Vitamin D?

  • Kali said,

    A doctor recently told me that us people in the Pacific Northwest (in Washington state) should take total 1,000-2,000iu of vitamin D. My multivitamin has 800iu and I just got a vitamin D supplement of 400iu. Do you think that’s ok? I also take total 950iu of Calcium, because to prevent Osteoporis, (recommended by another dr. of mine)like my mom has. (I’m 39)

  • Anna said,

    Mary,

    At 40 ng/mL you are not “well over” the established limits at all, though the majority of doctors will think your level is fine (my very conventional endocrinologist thought the 40s was fine for me, but my more creative and thoughtful primary doc thought I should get it higher.

    Your level is just barely inside the bottom of the reference range, which is 30 ng/ml by most labs. At least over 50ng/ml is generally considered a more optimal level by those who keep up with Vitamin D research.

    Living in the Northeast, you are lucky to even have a D level that high (all but one of my upstate NY family members were extremely deficient when they tested this winter, even the teenage girls, due to overcast climate, little or no D3 supplementation other than skimmed milk, and liberal high SPF sunscreen use).

    Taking 1000iu daily you won’t have to worry about toxicity at all. You can take several times that amount without worry. Our family tries to keep our 25(OH)D level between 70-80 ng/ml, and we need to take 1000iu per EACH 25 pounds of body weight to achieve that in the coastal San Diego region. That’s 3000iu for our 10 yo son during the school year when he’s indoor more, 5000iu daily for me (age 47), and 8000iu for my husband (age 54). Even in SD, CA, I could only get my level to 44 taking 2000iu daily. I tried getting more (prudent) sun instead of supplements last spring and summer (including a 2 wk vacation in Italy) and my level dropped to 40 ng/mL in late August, when I would have the highest levels of the year. Purdent sun exposure wasn’t enough. 5000iu D3 daily brought it up to a nice 76 ng/ml this winter and I feel much better than I’ve felt in years – more stamina & energy, more resistance to colds, better winter mood.

    Good luck to you.

  • Hend said,

    Dr. Holick-I am a Muslim woman who covers. I am studying dietetics and one of my concerns is that many Muslim women are not getting enough Vitamin D–either from the sun or from food or supplements. I am trying to get some help to conduct a study or some sort of education for Muslim women. Could you give me any advice…point me to some tools?

  • Debra said,

    I have been diagnosed with RA and also Vitmin D level is deficient at 17.I was put on a Rx of Vitamin D for 8 weeks then told by my rheumatologist to take caltrate with D.I just started having the same muscle pain and fatigue that made me seek attention in the first place. My liver enzymes are also slightly elevated and I take 5mg of Folic acid per day for this.
    My question is should I try to get more sun exposure, or wait until my doctor gets the level results back to see if I am still deficient? I believe in my own opinion it has deceased and since I know I have a issue already it is worrisome.

  • Anna said,

    Is there any danger in a very high 1,25 level??? Mid May, my 1,25 level was 130 (normal is 6-62) and yet my OH was only 46.2. I had been tanning (NYC murky sunlight, some tanning booths and supplementing with around 800 iu of vitamin d3 per day.) I subsequently have upped my supplementation to 2,400 IU per day plus outdoor sunshine. I’ve been feeling inexplicity exhausted and often nauseaus? Can I have gone toxic??? I weigh 105 pounds, am 46 year old female. My diet is near paleo style: NO dairy — just organic meats, fish, organic veggies, nuts and fruits. I drink all manner of teas and some coffee. I eat sardines & salmon with bones and also chew on chicken bones and eat the marrow. No calcium supplements. I take hypothyroid meds (armour plus cytomel). Anyone have any lay persons non-medical advice thoughts on what could be causing the fatigue, weakness and intermittent nausea???

  • Lamya said,

    Dr. Holic,
    My vitamin D level was found to be 17nmol/l, i started taking vitamin D3 but it made me very photo sensitive even very strong sunsblocks are not effective with me. only 15 min indirect sun exposure would make my face as if just came out of an oven so i stopped taking vitamin D and the sun is more tolerable for me now but my levels are still low!!
    do you have any suggestions?

  • D.L. Smith said,

    Are you aware of any studies that have looked at whether or not there is a difference in the “biological potency” of supplement-induced vitamin D vs UVR-induced vitamin D?

  • Kurt Butler said,

    Shame on Dr. Holick for appearing on Coast-to-Coast-AM right after yet another of the program’s many hysterical anti-vaccination propaganda sessions and not taking George to task for it and registering a strong dissent. These nuts are killing people. Responsible physicians should boycott the show until it gives equal time to vaccination rationalists. Otherwise you lend credibility to the garbage. Also, an award from the Linus Pauling foundation (or whatever it’s called) is nothing to be proud of. Pauling and his followers
    promote(d) lots of pseudoscientific clap-trap. After decades of promoting the miracles of massive (and dangerous) doses of vitamin C for everything under the sun there is still no evidence for their claims, yet they persist. However, I applaud your excellent work on vitamin D.

  • joe said,

    Are there vitamin D benefits associated with the light produced by tanning beds?

  • Ann said,

    I was feeling very tired and sluggish, went to my doctor who ran full battery of tests. My vitamin D level was only 10. Severely deficient. I was put on 50000 iu three times a week and immediately felt better. Took this dosgae for 3 months. Then my doctor took me off saying I was “full” and should be fine. About 8 weeks after I stopped taking the D I began to feel sluggish and tired. Went back to the doctor told him my D was low again- he said it couldn’t be, he had filled my store house with D. I asked for another D test anyway, and sure enough I was very low again. So, I am on 50000 iu, once a week – feel better again. Had not realized just how much we need out D.

  • Johanna Sayre said,

    A wonderful website, but it would be good–if possible–to have responses to some of the issues raised.
    So far missing in my perusal of the website, are age references, and ultra-violet, and infra-red lamp exposure, esp. in the winter.
    Age: I am 81, have serious health issues from osteoporosis, to RA factor, Hep. C, and very ‘weak’ input from the primary doctor and specialists as to how/where these aspects intersect and how e.g. Vit D fits into the picture.
    I have a long background of sun exposure information. From being toddlers we were put into the sun, for carefully monitored time, from 10′ building up to 20′ or 25′ then back down, then back up again, over weeks of this in the summer. My mother put rendered pig’s fat on us (unsalted), and a little white hat. In the winter ultra-violet lamp exposure was part of the routine. It started with 3′ going up to 8′ to 10′; then down etc. Distance from the lamp was as important as duration.
    I remember that being on water, and in snow was a consideration in the type of sun exposure, and protective care, esp. eyes. Sun baths in winter were of course plus clothes, but the idea of being on a deck chair in blankets, in the sun, has been with me from early childhood.
    All this, I would say was quite common knowledge.
    Later, things were more irregular and out of control because of the war. But still later, one summer, I went to a ladies’ sunbath regularly. For about two years hence it was a time of being and feeling well.
    This summer I started–somewhat late, alas–with sun baths, at a time when I am beset by health problems. The sunbaths are just wonderful, and I long for sunny days.

  • Mel said,

    I had severe fatigue ,nervous issues and alot more symptoms start about a yr ago and several specailists and tests later my vit D was low (D2 was 4 ,D3 was 17) total D was 21……..also my bun alt als levels were the “low” normal….was weird with all my symptoms and no findings at first , i was labeled anxious,depressed and basically hypochondriac! i was humiliated…most doctors dont agree that vit D def can have a huge affect on ones health…should more doctors be educated on this world wide issue?

    MY issue is i dont seem to tolerate taking D3 my body gets lethargic after taking it and i even pass out…this is with any amount. of course this made me look even more insane …but ive come to find out im not the only one like this.

    i handle sun well but dont think im getting enough….im in NC and soon will be moving to NY even worse for sunshine…
    my body /muscles are losing weight , i have pains in legs and all over… blood press goes up and down….
    this vit D seems to effect the whole body systems….

    my whole body seems to be off…..i read about a sun lamp on sperti i think its called…….will this lamp really work for 300 dollars?
    or is the FL sun best and worth the move there?

    i only take 600iu of plain D from right aid its ergocalciferol not D3 which i cant seem to tolerate…its a hard chalky pill…..and i seem ok with it somedays…..i try to drink almond milk with D2 and eat eggs alot….for D3 but i know this isnt sufficient.
    its a catch 22 here most high cholesterol foods have D3 but you need D3 to regulate it….!so if your deficient your cholesterol will be high!

    I looked into D3 and its source and most are made from lanolin or sheeps wool……..im highly allergic to wool in general could this be why i cannot even take a supplement that was processed from it????

    i noticed too that i dont seem to process fats the same as i use to , cant tolerate fish oil or certain fats…my stool floats……..never had this before.

    i was told to take D2 50,000 iu week but refused only because if my body cant tolerate a sm amt at this point what would happen with such a high dosage…i think sm amt over long periods is best in my case.

    for now i try to get sunlight on the porch but would like to know what hrs here in NC are best for the rays i need.? and what about NY?

    this is very scarey going through this D deficiency and i wonder if its not the cause of most diseases in this world….ive never felt worse ! and hope someone comes up with some alternative way to get D for pple who cant tolerate it or for pple i know who just dont absorb it…..

    Is there hope for us doctor ????

  • Saida Abdul-Aziz, RN said,

    You have inspired me to change my approach to community health. I also changed my Masters project to discss the cult\ural implications of Vitamin D Deficiency in African American Veiled Muslim women and have started to look at the possibility of completing research on this phenomena at the Doctoral level. I am wondering if I have sited you extensively and wanted to have permission to use your quiz aws an assessment tool to have school nurses assess their knowledge and seek more. I have cited your work so that it may be located easily. May I have permission or is ther a charge. I do not intend to sell or distribute your work without crediting. Would appreciate a response and discussion when I complete my MSN/MBA-HCM about taking your work to nurses Internationally.

  • Evelyn said,

    I was taking 1000 IU of a liquid Vitamin D3…[one used by researcher here in Canada] for about 4 years. My 25[OH]D level was 94nmol/L.
    In Jan.2009 I upped my Vitamin D to 3000 IU. At the end of the summer I had a cataract removed and the eye doctor insisted that I use Maxitrol[antibiotic& steroid] eyedrops in my eye after surgery to prevent infection. even though I’m allergic to steroids. After a few days on the eyedrops I had severe muscle,bone,joint and ligament pain.I also have RA which up to this point I felt was benefiting from Vitamin D.I went for a Vitamin D blood test and my blood level dropped from 94 while on 1000 IU vitamin D down to 81 while taking 3000 IU. I had upped Vit D to 5000 IU just before the surgery.
    What caused my Vitamin D level to drop and for me to have such pain?Could it have been the steroid eyedrops depleting the Vitamin D?
    I would appreciate a reply through my email from Dr,Hollick if possible.

  • Jeannie said,

    Dear Dr. Holick:
    After listening to your interview with Alan Chartock of WAMC, I asked my PCP for a 25-hydroxyvitamin D test. My level is 17.5. I live in the northeast and am only outside while commuting. Can I bring level up to acceptable levels by over-the-counter supplementing? And if so, how much would I take?

  • V.P.Veluswamy MD said,

    Dr Holick, I am a retired Physician. I attended the SMA conference in Dalla TX in Dec 09. Your talk on Vitamin D was both enj0yable and instructional. I teach preventive cardiology. I have to look at osteoporosis as a preventable disease and inform the public. Is your lecture on Vitamin D, available as a DVD?? If so I would like to get one. If not I recommend that you produce one for Physicians and I will buy a few to give it to my physician friends in USA and abroad. V.P.Veluswamy MD 941-3834249.

  • Alex said,

    DR.Holick
    I have had lots of problems going on with me and nothing Dr.s can’t find nothing wrong with me!I lost 27 lbs in 2 months and my DR. says it’s Fibromalgia and IBS!! My Vitamin D level is 19 and i have been diagonse with Hypocalcema before in the past while i was in hospital for stomach pains my Sed rate is @ 39 and some protein in urine.Dr checked calcium and their normal. Does Perdisone affect lab results? And what Dr. Should i get refered to? or should i go with anti-deprsents and treat (fibro) and (IBS)….

  • Janet Beale said,

    What is upper limit of Vitamin D supplementation? I have been on 50,000 units twice a week for six months without testing and I am concerned I am getting too much.

  • Gabriela said,

    I’m 38 and my doctor said that my level of vit. D is like a woman in hers 70’s. I’m really scared. I’m from North Brazil and I was constantly exposed to the sunlight and since I came to America I stopped this exposure. Do you think that this is the reason that I have this low level of vit. D? I also got obese; I’m 40 pounds over my normal weight. I would like to increase the level of vit D in my body as soon as possible. The days here where I live are always cloudy; we are still in winter time. What do I do?

  • clay berger said,

    Bravo, the sun is no longer a villain! I practice the George Hamilton Plan. He is known for his fabulous tan and so-so acting. In an interview in a men’s magazine, he was asked what sun block he used. He replied he never used any. He stated that he never stayed out in the sun long enough to burn. I adopted that program and get 15 minutes on the front and 15 on the backside and call it a day, all year round. It works great even in the winter.

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