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Sunscreen affects vitamin D production; but by how much?

Posted on: May 19, 2012   by  Brant Cebulla


Believe it or not, the effects of sunscreen application on vitamin D production are not fully understood. In the past, some studies show that sunscreen blocks all production, while others show that a little bit of vitamin D can still be produced. Last month, a team of researchers clarified the confusion.

The researchers, led by Professor Annesofie Faurschou, theorized that sunscreen thickness determines whether you can produce vitamin D or not, and based on the thickness, determines how much you produce. So they set up a randomized controlled trial to find out.

Faurschou A, Beyer DM, Schmedes A, Bogh MK, Philipsen PA and Wulf HC. The relation between sunscreen layer thickness and vitamin D production after UVB exposure – a randomised clinical trial. British Journal of Dermatology, 2012.

The investigators recruited 37 healthy participants between the ages of 18 and 49, all with skin types between very fair and creamy white. The participants were then randomized to apply sunscreen in layers of 0 mg/cm², 0.5 mg/cm², 1.0 mg/cm², 1.5 mg/cm² or 2.0 mg/cm² to approximately 25% of their body. They used SPF 8.

After the participants applied sunscreen, they waited 20 minutes before exposing themselves to UV via florescent tubes. The researchers gave every participant a UV dose of 3 SEDs (enough UV exposure to produce a slight pinkness to the skin in most skin types). This exposure was only applied to the 25% of skin that was covered by sunscreen.

This procedure was repeated four times, with 2-3 day intervals between each visit. The researchers measured 25(OH)D levels at baseline and then three days after the participants’ last visit. The results are displayed in the table on the right.

As you can see, the increase in vitamin D levels shows exponential growth the thinner the sunscreen application. There is a fourfold difference between applying 2 mg/cm² and no sunscreen at all. Even a small layer of sunscreen at 0.5 mg/cm² produced half the increase in vitamin D compared to no sunscreen.

The Vitamin D Council recommends a balanced and sensible approach to sun exposure, taking into consideration both vitamin D production and protection from burning. With all this in mind, on a sunny day, we recommend exposing yourself for half the time it takes to turn pink, and then covering up, preferably with clothing or shade.

If you must use sunscreen to protect your skin from UV exposure, you should slather the sunscreen on in large quantities. This study shows that since vitamin D production is compromised by at least twofold, if not fourfold, no matter the thickness, you might as well focus on protecting your skin, rather than trying to protect your skin and produce vitamin D simultaneously.

In summary:

  • You cannot adequately produce vitamin D and protect your skin at the same time.
  • You should separate time for vitamin D production and time for skin protection.
  • The Vitamin D Council recommends full body exposure before you turn pink. Then, cover up with clothes or shade. If you must use sunscreen instead of clothing/shade, apply sunscreen generously.

5 Responses to Sunscreen affects vitamin D production; but by how much?

  1. [email protected]

    Interesting, really. I saw reports about this study in danish and norwedian news, but nothing, nothing in our swedish dito. And the recommendations about vitamin D is handled by the Food Department, and they know absolutely nothing. A quote; “the line between normal D-level and toxic D-level is thin”. As soon as their new rapport will come, I ´ll send the D recommendatins to VDC.

    I always loved the sun and sun-bathing and I still do. I noticed something interesting since I began with adequate doses of vitamin D, I don not even get slightly pink from the sun. I get tanned rather easy, but now I also do keep my tan during winter!? Not so wintery-white:-) I also noticed I can be out in the sun all day without getting burned or red. Ok, I wouldn´t go to Turkey and lie in the sun all day, without protection … but I can do it in the south of Sweden, 55º at this time of the year. Maybe I should make a test to see how pink-red I can turn after a full 8-hours day in the sun

    I discussed this with a lot of people and many have noticed this, they do not burn easy anymore and some say it takes longer time to get the real dark tan.

    We must be quite a number of people now, knowing our vitamin D-level?
    It would be fun to know the individual experiences in how the skin-reaction and tanning might have changed, among us … also to know how many colds and flus , if any … we get..

  2. Ian

    [email protected]
    What would you consider a toxic vitamin D level? (I assume you are referring to the serum level not the supplement dosage, as it is impossible to overdose on the sun).

  3. [email protected]

    I recall an earlier study indicating at least 10 chemicals are produced in the skin from sun exposure. Has there been any further investigation to actually how many (and what they do) are actually produced?

  4. [email protected]

    Ian, I am going to tell you something very fascinating and important.

    I have never ever in my life seen a patient with av vitamin-D3-intox!
    I have red about it, but never ever saw a true descrition of one either!
    Never saw any proof, ie a sick person with very, very high 25(OH)D,
    not even anecdotal …

    Anyone saw that?

    A study by Brohult och Jonssons with 100 000 IU D-vitamin per day. [Brohult J, Jonson B. Effects of large doses of calciferol on patients with rheumatoid arthritis. A doubleblind clinical trial. Scand J Rheumatol. 1973;2(4):173-6.]
    That makes 2 500 µg/day in one year of time without toxic effects.

    “Until further experimental evidence, adequate and incontrovertible, is made available, I submit that we should play for safety. In a climate like that of England every pregnant woman should be given a supplement of vitamin D in doses of not less than 10,000 IU per day in the first 7 months, and 20,000 IU (per day) during the 8th and 9th months.”

    [OBERMER E. Vitamin-D requirements in pregnancy. Br Med J. 1947 Dec 6;2(4535):927].

  5. boston

    read this article from vitamindcouncil about excess vitamin d studies –and also about Gary Null’s experience….

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