Yes, vitamin D is made by sunshine; however, in the northern latitudes, the sun is only strong enough to stimulate vitamin D production in your skin 3 to 4 months a year, typically from May through August. Your skin will make enough vitamin D to support good blood levels if you are outside for at least 10-20 minutes a day, without sunscreen, typically between 10:00am and 2:00pm in shorts and a tank top. Do most people get this amount of sun exposure? No. While I am not advocating NO sunscreen, I do think it would be OK to spend 10-20 minutes without it if you are trying to get your vitamin D. Then, go and slather up with a broad-spectrum SPF. If your vitamin D levels were low before the summer, or if you aren’t outside much without sunscreen during the middle of the day, you should continue your supplement.
Susan Blum, M.D.