Vitamin D Deficiency: Treat With a Supplement or Sunlight?

treat vitamin D deficiency

A friend recommended his nutritionist on Facebook. I visited his site only to come across THIS in an article about vitamin D deficiency and benefits:vitamin D deficiency

My eyes started twitching. Apparently if you don’t have Vitamin D deficiency, then you won’t get burned! There’s research to support this plus a bunch of bloggers say so!

I wouldn’t get extremely angry if skin cancer rates were on not the rise and if we didn’t have more skin cancer cases from UV exposure than lung cancer cases from smoking! Now if you get skin cancer because you thought Vitamin D had you covered, well, c’est la vie.

Because I’m sick and tired of this sunscreen, vitamin D, sun exposure debate, because I’m sick of cherry-picked studies and the wrong information being spread out, I’m gonna put an end to this, today. We’ll cover exactly how to balance sunlight with Vitamin D supplementation to treat Vitamin D deficiency:

  • Why do we need Vitamin D?
  • What are adequate levels of Vitamin D? When do you have a Vitamin D deficiency?
  • How much sunlight do you really need for Vitamin D production?
  • If you supplement with Vitamin D, what’s the right daily Vitamin D dosage for you?
  • How do you balance the trade off between getting enough Vitamin D but not risking skin cancer?

First, why is Vitamin D important for our health?

We’ve all heard about the skeletal benefits of Vitamin D. But it appears we were only scratching the surface. Vitamin D deficiency is linked to increased risk of all sort of different diseases. Quoting WebMD:

There is recent and mounting evidence that links low levels of the vitamin to an increased risk of type 1 diabetes, muscle and bone pain, and, perhaps more serious, cancers of the breast, colon, prostate, ovaries, esophagus, and lymphatic system.

Now who wouldn’t want to get protected from all these diseases? It’s a no-brainer we should aim for adequate Vitamin D levels. But…

The issue: Our population is generally suffering from vitamin D deficiency. This has now reached public health concern status.

Most of us need Vitamin D dosage of 600 IU a day (or higher), yet many of us have less than we should. Most studies talk about our vitamin D deficiency. According to Cristina Palacios and Lilliana Gonzalez:

Vitamin D deficiency is a major public health problem worldwide in all age groups, even in those residing in countries with low latitude, where it was generally assumed that UV radiation was adequate enough to prevent this deficiency, and in industrialized countries, where vitamin D fortification has been implemented now for years.

This has now reached public health concern status. A 2013 study in the European population concluded that infants, children, and adolescents are suffering from Vitamin D deficiency. Heck, even farmers may be Vitamin D deficient! Bodekær et al. conclude:

UVR exposure was generally high among this study population, however, vitamin D levels still dropped below the recommended level during winter for most participants. Differences in UVR exposure between the groups did not result in differences in vitamin D levels.

So how do you know if have Vitamin D deficient? And what are the optimum Vitamin D levels?

You need to do a blood test to find out if you have a vitamin D deficiency. A wide “optimal” range for Vitamin D is reported (25-80 ng/mL), and differences of opinion exist as to the definitions of vitamin D insufficiency (sometimes reported as <30 ng/mL) and Vitamin D deficiency (<20 ng/mL). A level of 20 nanograms/milliliter to 50 ng/mL is generally considered adequate for healthy people.

However, this guideline is now being revised. I’ve seen multiple studies suggest that being in the 40+ range best, with an absolute minimum being 30 ng/mL. For example, Christoph von Domarus et al. conclude that “the combined analysis of bone mineralization and vitamin D status has established minimum levels of more than 75 nmol/L (30 ng/mL) to guarantee at least skeletal health.”

If you’re a bit of a nerd, and are interested in learning the right Vitamin D levels to help prevent a number of diseases ranging from bone fractures to cardiovascular disease, then please go through this paper. It’s not too hard to read, promise!

Despite what you may read on the internet, or on Mercola, Vitamin D does not prevent from burning and does not protect from melanoma either.

Yes, Vitamin D is awesome. But that doesn’t mean it’s an all powerful panacea with magic properties.

First, no, Vitamin D does not prevent from burning.

The nutritionist I mentioned at the beginning claimed there’s research that supports that supplementing vitamin D can all by itself prevent burning. I clicked the link to the study. It’s an animal study. It’s done on freaking mice! Here’s what the authors, Dixon KM et al., say:

“The observed reduction of these UV-induced effects by 1,25(OH)2D3 and JN suggests a role for these compounds in prevention against skin carcinogenesis.”

They talk about a “role” in prevention. That’s it. I’ll add: This is ONE study, done on mice. That’s very different than concluding that yay, as long as you don’t have Vitamin D deficiency, you’re not going to get burned!

This is far away from having multiple studies, on humans, drawing the same conclusion. Because that’s what we’d need to make that strong claims.

Second, no, Vitamin D does not seem to protect from melanoma, despite what Mercola says.

This is what I found on Mercola suggesting the opposite: it’s actually lack of sunlight (and hence lower Vitamin D) that promotes skin cancer! So sunlight decreases your skin cancer risk! What a dangerous lie. Let me explain.

“A study in Medical Hypotheses suggested that indoor workers may have increased rates of melanoma because they’re exposed to sunlight through windows, and only UVA light, unlike UVB, can pass through window glass. At the same time, these indoor workers are missing out on exposure to the beneficial UVB rays, and have lower levels of vitamin D.”

I was intrigued by this claim. I looked up the study. It is published in a “Medical Hypotheses.” The name of the publication seemed weird. So I went to their “submit a manuscript” page. This is what I found:

“Medical Hypotheses takes a deliberately different approach to peer review. Most contemporary practice tends to discriminate against radical ideas that conflict with current theory and practice.

Medical Hypotheses will publish radical ideas, so long as they are coherent and clearly expressed. Furthermore, traditional peer review can oblige authors to distort their true views to satisfy referees, and so diminish authorial responsibility and accountability. In Medical Hypotheses, the authors’ responsibility for the integrity, precision and accuracy of their work is paramount. The editor sees his role as a ‘chooser’, not a ‘changer’: choosing to publish what are judged to be the best papers from those submitted.”

In other words, this is not a peer-reviewed journal. This is a publication where the editor selects the studies without scientifically studying them. Not impressive, not impressive Mercola, you need to give better evidence than that to make the strong claims about vitamin D and skin cancer protection.

Here’s what I found in the Journal of Investigative Dermatology: no connection between vitamin D and melanoma.

“After controlling for age, hair Color, and family history of melanoma, there was no association of melanoma risk with total vitamin D intake, caloric-adjusted vitamin D intake, vitamin D intake from foods, or consumption of milk or vitamin D supplements. We find no evidence to suggest that vitamin D protects against melanoma, and therefore continue to support the ongoing public health campaigns aimed at reducing sun exposure for the prevention of melanoma.”

In fact, sun exposure increases melanoma rates.

Melanoma is caused by a number of reasons including genetics. However, UV radiation is estimated to account for 50% to 90% of melanoma or basal cell skin cancer and 50% to 70% of squamous cell skin cancers worldwide (Lucas RM et al.)

So how do you get the right Vitamin D dosage to treat a Vitamin D deficiency?

No, you can’t treat Vitamin D deficiency through good diet alone. You either need sunlight or a supplement.

I wish we could just focus on diet, but the right answer is that it’s really hard to eat enough Vitamin D rich foods (like fortified dairy products, cereal, and salmon) to get to adequate levels, without being exposed to sunlight.

So if you want to have good Vitamin D levels, you either need to get out in the sun, or get a good Vitamin D supplement.

Now if you go out in the sun keep in mind that sunscreen use may reduce your Vitamin D levels.

Most studies (Matsuoka et al., Linos et al., Faurschou et al.) suggest that using sunscreen interferes with Vitamin D production.

But before you choose sunlight over supplementation know that we overestimate how much sunshine we need for Vitamin D production.

A 2008 study said we think we need more than 10 minutes of exposure every day to produce adequate Vitamin D. So that’s more than 70 minutes a week.

Silva et al. recommend for the tropics just 5 minutes of exposure with unprotected forearms and hands at peak hours! 5 minutes are enough on a clear day, during peak hours, to create enough Vitamin D! You know how much this changes in winter? The number goes up to a whooping 11 minutes!

Ok, but that’s for the tropics and Skin Type II. What about fair-skinned people? I wrote about this study from Australia in my benefits of tanning article:

  • In the summer 2-14 minutes at 12 pm 3-4x a week are enough. So a total of say 10 minutes a week at 12 pm is fine as far as Vitamin D is concerned.
  • In spring or fall 10-15 min 3-4x a week at 10 am or 3 pm are also enough to produce Vitamin D. So a total of 30 min a week, when the sun is not at its peak, are fine for Vitamin D production.
  • In the winter, the study suggests we need longer exposure time. Makes sense if it’s rainy or cloudy most of the time!

Do you choose a supplement or sunlight to treat Vitamin D deficiency or insufficiency?

Now of course, going out in the sun risks skin cancer, so you know what my preferred method of increasing my Vitamin D levels would be!

For supplements: we most likely need a supplement of 1000 IU/day, not less than that.

As Hollick MF suggests in the American Journal of Clinical Nutrition: “The recommended adequate intakes for vitamin D are inadequate, and, in the absence of exposure to sunlight, a minimum of 1000 IU vitamin D/d is required to maintain a healthy concentration of 25(OH)D in the blood.”

Now this finding is especially important if you’re sunlight-deprived. In a Danish study published on the Journal of Internal Medicine, Glerup H et al. conclude that the daily oral intake of vitamin D in sunlight-deprived individuals should be 1000 IU per day. In this study individuals who supplemented with 600 IU had still vitamin D deficiency, hence the higher daily dose recommendation.

Note that these values are recommended for maintenance: not to correct a vitamin D deficiency. Vin Tangpricha, MD suggests: “Regardless of initial vitamin D therapy, and assuming no change in lifestyle or diet, a maintenance/prevention daily dose of 800 to 2000 IU or more will be needed to avoid recurrent deficiency.”

So how do you treat Vitamin D deficiency without risking skin cancer?

Is Vitamin D important? Yes. Are you likely to be deficient? Yes. What should you do about it?

First, do a blood test to check your levels. If you get values lower than 30 ng/mL, then you’ll need to start pumping up your Vitamin D.

Sure you can increase your intake of vitamin D rich foods (check this database out for a full list), but this is probably not going to help much, unless you expose yourself to the sun, or also take a supplement.

Now going out in the sun more comes with the risk of skin cancer, so I wouldn’t recommend it. Skin cancer is on the rise already, and if you’re like me, you also have no intention of exposing yourself to carcinogenic UV rays when there’s a safer way to increase Vitamin D levels.

Instead if my values indicated Vitamin D insufficiency, I’d probably take a 1000 IU/day vitamin D supplement. Note that many multivitamins do contain Vitamin D, but the 400 IU dose is thought to be too low, so don’t think that the multivitamin alone should cover your needs. Check the dosage and ask your doctor to determine what is right for you. Vitamin D dosage may change depending on your age, health, and whether you’re pregnant or not.

Now if your values indicate Vitamin D deficiency, the doctor will most probably create a dosage plan for you, so that you move from vitamin D deficiency to insufficiency to normal levels. You’ll most likely get tested again after a while to check your progress.

Some people may be inclined not to expose themselves to the sun, but to instead keep their current exposure levels but limit their sunscreen use. Don’t do it. Sunscreen helps protect from skin cancer, are you sure you want to risk it? And no, don’t replace your sunscreen with coconut oil please! That’s no suncreen!

And next time you encounter crazy claims, like “sunlight decreases your risk of skin cancer” or “Vitamin D prevents from burns,” well, now you know better.

Have you ever tested with a vitamin D deficiency or insufficiency? How did you go about it? What did your doctor recommend? Leave a comment below.


Cristina Palacios and Lilliana Gonzalez, Is vitamin D deficiency a major global public health problem?, The Journal of Steroid Biochemistry and Molecular Biology, Volume 144, Part A, October 2014, Pages 138–145

Vin Tangpricha, MD et al., Vitamin D Insufficiency among Free-Living Healthy Young Adults. Am J Med. 2002 Jun 1; 112(8): 659–662.

Dixon KM et al, 1?,25(OH)?-vitamin D and a nongenomic vitamin D analogue inhibit ultraviolet radiation-induced skin carcinogenesis., Cancer Prev Res September 2011 4; 1485

Braegger et al., Vitamin D in the Healthy European Paediatric Population, Journal of Pediatric Gastroenterology & Nutrition: June 2013 – Volume 56 – Issue 6 – p 692–701

M. Bodekær et al.,  UVR exposure and vitamin D in a rural population. A study of outdoor working farmers, their spouses and children, Photochemical & Photobiological Sciences Issue 11, 2014

Lucas RM et al., Estimating the global disease burden due to ultraviolet radiation exposure. Int J Epidemiol, 2008;37:654–67

Naylor MF, High sun protection factor sunscreens in the suppression of actinic neoplasia., Arch Dermatol. 1995 Feb;131(2):170-5.

Thompson SC et al., Reduction of solar keratoses by regular sunscreen use. N Engl J Med. 1993 Oct 14;329(16):1147-51.

Autier P et al., Melanoma and use of sunscreens: an Eortc case-control study in Germany, Belgium and France. The EORTC Melanoma Cooperative Group.  Int J Cancer. 1995 Jun 9;61(6):749-55.

Adèle C. Green et al., Reduced Melanoma After Regular Sunscreen Use: Randomized Trial Follow-Up. JCO, 2010

Dianne E. Godar et al., Increased UVA exposures and decreased cutaneous Vitamin D3levels may be responsible for the increasing incidence of melanoma, Medical Hypotheses, 2008

Martin A Weinstock et al., Case-Control Study of Melanoma and Dietary Vitamin D: Implications for Advocacy of Sun Protection and Sunscreen UseJournal of Investigative Dermatology (1992) 98, 809–811; doi:10.1111/1523-1747.ep12499962

Matsuoka et al., Sunscreens Suppress Cutaneous Vitamin D3 Synthesis, The Journal of Clinical Endocrinology & Metabolism, 2013

Eleni Linos et al., Sun protective behaviors and vitamin D levels in the US population: NHANES 2003–2006, Cancer Causes & Control,January 2012, Volume 23, Issue 1, pp 133-140

A. Faurschou et al., The relation between sunscreen layer thickness and vitamin D production after ultraviolet B exposure: a randomized clinical trial, British Journal of Dermatology Volume 167, Issue 2, pages 391–395, August 2012

Rutten et al., Public perceptions of cancer prevention, screening, and survival: Comparison with state-of-science evidence for colon, skin, and lung cancer, Journal of Cancer Education, March 2009, Volume 24, Issue 1, pp 40-48

Abel A. Silva., Improving Photoprotection Attitudes in the Tropics: Sunburn vs Vitamin D, Photochemistry and Photobiology, Volume 90, Issue 6, pages 1446–1454, November/December 2014

Neale R et al., Application patterns among participants randomized to daily sunscreen use in a skin cancer prevention trial. Arch Dermatol, 2002; 138:1319–25.

Schneider J., The teaspoon rule of applying sunscreen. Arch Dermatol, 2002;138:838–9.

Hollick MF, Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis. American Journal of Clinical Nutrition, 2004 Mar;79(3):362-71.

Glerup H et al., Commonly recommended daily intake of vitamin D is not sufficient if sunlight exposure is limited. Journal of Internal Medicine, 2000 Feb;247(2):260-8.

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  1. Really, Maria, I enjoyed reading your informative article especially after having
    been diagnosed with low vitamin D levels. I am 63yo otherwise healthy, fit
    American male living in France under a doctor’s care.

    Here is my
    story…. After the first blood analysis, identified low vitamin D, my
    doctor confirmed with a second test a few months later. She initiated a
    6-month regime as follows: On the first day of months 1, 2, 4 & 6, I
    am to take 80,000 IU vitamin D (yes, 80k IU), four doses. I have completed months 1
    & 2.

    I had never heard of such a treatment, perhaps a shock treatment but after investigating,
    this is not a rare procedure in France. I await having my blood analysis
    after month 6. Truly a regime to be undertaken under a physician’s

    1. Hi Daniel, well the big dose makes sense since you were diagnosed with deficiency. It’s high but it’s not extreme. Also keep in mind it’s a monthly, not a daily dose, which is part of why it seems so high. I’m glad you’re under the care of a doctor. Keep it up!

  2. Hello
    I am in the VITAL study, looking at vitamin D & omega 3 FA. The 5 year study is over in December-I’ll find out what I’m taking in January. And the results? I imagine in the next few years we’ll discover whether these nutrients perform their magic! I’m guessing not-but we shall see.