The body manufactures vitamin D when the sun’s UVB rays interact with 7-dehydrocholesterol (7-DHC) in the skin, covnerting it into vitamin D3. Sunbathing defeats the purpose for many reasons:
First, it takes only a few minutes of sun-as little as five minutes of exposure to the face, arms or back twice weekly-for the body to manufacture sufficient vitamin D. If you have more sun that-certainly if you sunbathe long enough to tan-your store of vitamin D actually starts to deplete, breaking down into inactive compounds.
On the other hand, with each passing minute of sun exposure, the amount of damage to your skin cells – to your skin’s DNA – keeps rising. Tanning is a direct response to DNA damage to your skin cells – your body’s attempt to build a wall of dark pigment against further damage. The damage accumulates over a lifetime. Over 86% of melanomas and 90% of nonmelanoma skin cancers are linked to sun ultraviolet light.
Given that UVB rays stimulate the skin to produce vitamin D, and tanning beds are predominantly UVA, this statement doesn’t hold any truth. The tanning industry quotes from a study where vitamin D levels increased in those utilizing tanning beds, however, the patients enrolled in that study had also done significant sunbathing.
Tanning beds are not safe. We now know that UVA penetrates much deeper into the skin, causing significant skin aging by producing free radicals. It also causes deep wrinkles and collagen destruction.