What about Vitamin D?
When your skin is exposed to UV radiation -- whether from the sun or from an indoor tanning device -- it makes vitamin D. Vitamin D is good for you. And there's strong evidence that getting plenty of this vitamin -- perhaps as much as 1,000 international units (IU) a day -- prevents several deadly kinds of cancer.
Haynes stresses the value of indoor tanning for vitamin D production. This anticancer benefit, she says, shows that indoor tanning is good for you.
"It is impossible to get too much vitamin D from sunlight," Haynes says. "If you take a supplement, it is possible to take too much and make yourself ill. Sunlight is free, and vitamins at the drug store cost a lot. You'd have to drink a gallon of milk a day to get 1,000 IU of vitamin D."
Levine says indoor tanning provides radiation far in excess of what is needed to get enough vitamin D. And too much radiation exposure, she says, can actually remove vitamin D from the body.
"There is a certain point at which too much radiation causes the vitamin D production pathway to go backwards," Levine says. "With extended exposure, vitamin D is converted back to its precursors. It is doubtful that the greater risks incurred by extensive tanning will be offset by the benefits of vitamin D from this radiation."