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. During these months, your skin will make enough D to maintain good levels of the vitamin in your blood, if you are outside for at least 20 minutes a day, without sunscreen, typically between 10 am and 2 pm, in shorts and a tank top. In other words: your arms and legs need to be fully exposed without sunscreen during peak hours of maximum sun. Do most people get this? No. So if you walk or exercise outside, spend time in the garden or other outdoor activities regularly, and don’t use sunscreen every minute, you’re probably OK taking the summer months off. But honestly, most of the patients I see don’t have an appreciable bump in their Vitamin D levels in the summer. They simply don’t get as much exposure as they think they need to stay on their normal regimen. And that could be you. While I am certainly not advocating no sunscreen, I do think it would be OK to spend 20 minutes without it, if you’re trying to get your D. Then go and slather up with a broad spectrum SPF! Blum is a member of the medical advisory board for The Dr. Oz Show and the Institute for Integrative Nutrition, and is on the board of directors for the True Health Initiative in the College of Lifestyle Medicine. She completed her internal medicine training at St. Luke’s Roosevelt Hospital and is board certified in preventive medicine, certified in functional medicine, is senior faculty with the Center for Mind-Body Medicine.
