Dear Dr. Walt,
I spend a lot of time in the sun, especially in the summer. Does this mean my vitamin D levels could get too high?
—Tanned in North Carolina
Dear Sun Seeker,
Nope. According to the American Academy of Dermatology, although spending short periods of time in the sun can usually provide adequate amounts of vitamin D, spending longer periods of time in the sun will not increase vitamin D levels to toxic levels.
This is because excessive exposure to sunlight degrades previtamin D3 (which is normally converted by sunlight into vitamin D3 in the skin) and degrades vitamin D3 itself.
But, it is very possible to get too much vitamin D from supplemental vitamins.