Vitamin D Newsletter


High vitamin D levels protect against sunburn

Justine from New Jersey writes:

My skin was much more resistant to the sun.

Dr. Cannell: I just came back from a vacation in the Caribbean and you are right about what you wrote a few years ago about vitamin D and sun sensitivity. Before, I always burned easily as I am fair-skinned. But, before this vacation I had been taking 5,000 IU per day for about 9 months. My skin was much more resistant to the sun; sometimes it would get red and I thought I was burned but the next morning it was gone.

Thank you, it is so great not having to always worry so much about getting burned.

Dr. Cannell replies:

Beware: vitamin D sufficient people can still sunburn, it just takes longer. Sunburns increase your risk of melanoma and other skin cancers.

You're welcome, but don't throw away your sunblock. If you remember from my past newsletters, my daughter Eliza discovered vitamin D's ability to prevent sunburn and my fair-skinned, river-rafting friend confirmed it. My daughter had been taking 5,000 IU per day for ten months and decided she wanted to tan in a suntan parlor. Instead of burning the first few times, she quickly developed a rich tan.

My friend took high doses of vitamin D for a few weeks before rafting and, for the first time in his life, did not burn when rafting the Snake River. In fact, a businessman is now selling a product at sun-tanning parlors to prevent burning; the product's active ingredient is simply 30 tablets of 10,000 IUs of vitamin D3, to be taken daily for one month before tanning.

This is the time of year many people sunburn. I have thought a lot about the whole issue of sunburning and would like to propose a theory. I do not think sunburning is entirely without an evolutionary benefit. The final conversion of vitamin D in the skin requires heat and the heat of sunburn will increase the amount of vitamin D made by any one sun-exposure. Thus, sunburns evolved for a reason. Nature cares less if you damage your skin with sunburn; Nature cares more that vitamin D deficient people maximize any one sun-exposure. That is, people with low 25(OH)D levels have a reason to burn, they make more vitamin D. Easy sunburning and sun sensitivity may simply be a symptom of vitamin D deficiency. This is also a good study for some young vitamin D scientist to do.

Vitamin D sufficient people do not need any extra vitamin D from the sun, so the extra heat in the skin generated by sunburn is not needed. (As an aside, I also predict that 25(OH)D exerts negative feedback on 7-dehydrocholesterol, vitamin D's precursor molecule.) Vitamin D sufficient readers will see, when they go into the sun this spring, that it takes longer to burn, that their skin is less sun-sensitive, and that when redness does occur, it is often gone the next day. However, beware: vitamin D sufficient people can still sunburn, it just takes longer. Sunburns increase your risk of melanoma and other skin cancers.

Also, some fair-skinned people have a genetic variation that prevents their skin from making melanin pigment. Theoretically, vitamin D should not help them from sunburning. But don't confuse fact with theory. The fact is that some skin type 1 people cannot make much melanin; the theory is that vitamin D will not protect their skin from sunburn. However, I know of some very fair-skinned, blond-headed, blue-eyed, skin type 1 people whose skin became less sensitive to the sun after taking 5,000 IU/day.

Page last edited: 07 November 2010