We all know that sunlight is associated with skin cancer and thus many of us fear exposing our skin to the sun. In a paper in Dermatoendocrinology, Drs. Lea Trémezaygues and Jorg Reichrath of the University of Saarlandes in Germany make the case that regular exposure to sunlight decreases the risk of malignant melanoma and perhaps the risk of non-melanoma skin cancers as well.
Trémezaygues L, Reichrath J. From the bench to emerging new clinical concepts: Our present understanding of the importance of the vitamin D endocrine system (VDES) for skin cancer. Dermatoendocrinol. 2011 Jan;3(1):11-7.
This was not the first time they have proposed this theory. The same group wrote about it in 2006. Both papers are free to download in their entirety.
Tremezaygues L, Sticherling M, Pföhler C, Friedrich M, Meineke V, Seifert M, Tilgen W, Reichrath J. Cutaneous photosynthesis of vitamin D: an evolutionary highly-conserved endocrine system that protects against environmental hazards including UV-radiation and microbial infections. Anticancer Res. 2006 Jul-Aug;26(4A):2743-8. Review.
The authors make the point that regular sun exposure greatly increases the amount of activated vitamin D in the skin. This activated vitamin D has multiple anti-cancer mechanisms of action and activated vitamin D in the skin dramatically reduces the damage UV radiation causes.
This is what the authors say about malignant melanoma:
“In contrast to short-term intense exposure, more chronic and less intense exposure has not been found to be a risk factor for the development of malignant melanoma. In fact, it has been found to be protective in many studies.”
They go on to quote studies showing that the higher your 25(OH)D at the time of diagnosis of malignant melanoma, the better the prognosis, leading the authors to conclude:
“Patients with melanoma, and those at high risk of melanoma, should seek to ensure vitamin D sufficiency.”
In terms of non-melanoma skin cancer (NMSC), the authors point out that the same anti-cancer mechanisms are at work in the skin and, “higher levels of 25(OH)D were associated with a decreased risk of NMSC. Men in the highest quintile of 25(OH)D (>30 ng/ml) had 47% lower odds of NMSC compared to those in the lowest quintile.”
However, I doubt the 25(OH)D has to be made in the skin in order to increase activated vitamin D in the skin. I suspect, but cannot prove, that higher 25(OH)D levels from supplementation also allows the skin to make lots of activated vitamin D and thus prevent skin damage.
I say this because those with high levels of 25(OH)D from supplementation continue to report to me that sun exposure no longer burns or damages their skin as it did when they were vitamin D deficient. I have noticed the same thing in my children and me; it’s a lot harder to burn than it used to be before I started taking vitamin D. Have you noticed the same thing?
Why would sunburns be less common in those with a high vitamin D levels? First, the high activated vitamin D levels protect the skin and, since the body needs no more vitamin D, there is no need to induce the heat of sunburn to promote the formation of vitamin D. Remember, the last step in the production of vitamin D in the skin involves localized heat like the heat of a sunburn. If true, then easy sun burning is a common symptom of vitamin D deficiency!