Question:
One of the skin's functions is to photosynthesize Vitamin D3 from
natural sunlight. As the body's provider of Vitamin D, the skin would
thus show initial signs of a critical shortage, which would affect all
ages of both genders and, if left uncorrected, would be fast-spreading
and deadly--just like malignant melanoma.
Somebody even did the experiment. Way back in 1981, a small group of
Stanford researchers added Vitamin D3 to a test tube with human
melanoma cells and noticed that it inhibited their growth. (See Colston
K, Colston MJ, Feldman D. "1,25-dihydroxyvitamin D3 and malignant
melanoma: the presence of receptors and inhibition of cell growth in
culture." Endocrinology. 1981 March;108(3):1083-6.) Since Vitamin D3
inhibits growth of human melanoma cells in a test tube, then why on
earth wouldn't it do so right where it is being generated in the skin?
I realize that new views are always painfully slow to find acceptance
in medicine, and so just as I've done the last few years, I'll review a
melanoma finding in a monthly follow up post and discuss how it is
explained by Vitamin D--or the lack thereof.
Answer:
Getting melanoma and dying from it is not a simple 'more sun, more
melanoma' equation. When melanoma patients with a history of high-level
sun exposure are compared with those with little sun exposure the
'sunny' ones have a better prognosis. This seemed a perplexing problem
and inferred higher vit D3 levels may influence prognosis. BUT I'm not
sure if the comparison was for same-stage disease because lifestyle
factors probably play a role here too -sun worshippers paying more
attention to their skin and thus having more early stage disease, for
example. In addition (primary) melanomas sometimes occur in places that
don't get sun exposure.
