Can Tanned Skin be Healthy?

Posted by Elaine Moore May 29, 2007

For many years a newly acquired tan was so closely associated with good health that the adjective healthy commonly accompanied the word tan. But alas, when the links between sunburn and skin cancer, and excessive sun exposure and aging, emerged, all that changed. Seeing a lucrative consumer market, chemical companies created products with higher and higher SPFs and found innovative ways to pump these products into hand lotions and cosmetics. Soon the excessive permeation of sunblocks resulted in too much of a good thing and the effects of vitamin D deficiency emerged, including a rise in autoimmune diseases.

With recent studies generating renewed interest in the benefits of vitamin D the benefits of tanning have been re-examined. In the May 24, 2007 issue of the New England Journal of Medicine, researchers explain the role of tanning in health.

What is p53?

The tumor suppressor and transcription factor protein known as p53 has guarded the human genome in multicellular organisms for the past 500 million years. In this role, p53 mediates the response of cells to DNA damage. It accomplishes this by inducing cell-cycle arrest and facilitating DNA repair. If the damage is severe, p53 eliminates the damaged cells by triggering apoptosis.

In fact, about 1 million years ago man showed evidence of a tanning response, in which melanin granules in keratinocyte cells developed in an effort to prevent the DNA damage associated with sunlight. Specifically, ultraviolet irradiation activates the p53 protein to stimulate transcription of its target genes, which include those that control melanin production and p53 activation. Gene mutations of the gene encoding melanocortin 1 receptor as well as deficiencies of p53 lead to red hair, fair skin, and the inability to tan.

An Adaptive Mechanism

As migration across the continents and the rise of agrarian occupations led to increased exposure to sunlight, the body adapted in its usual way--with genetic mutations. These genetic changes included increased production of p53. The increased p53, in turn, prevented the effects of DNA-induced sun damage while causing the skin to tan. Tanning has also been shown to cause immune system changes that reduce inflammation. The psychological benefits of tanning are suspected of arising from increased endorphin production in skin cells known as keratinocytes. Whether artificial tanning beds can cause the benefits of tanning remains to be seen.

Clinical Applications

Exposure to sunlight offers benefits that reach beyond vitamin D absorption including the activation of p53. The activation of p53 is being studied for its role as a cancer treatment, and the various degrees of sun sensitivity are being studied for their effects in autoimmune disease. As Hippocrates repeatedly said, all medicines can be found in nature.

Resource:

Gregory Barsh and Laura Attardi, A Healthy Tan? The New England Journal of Medicine, May 24, 2007, vol 356 (21): 2208-2210.