New York Times
Alice Callahan
Feb. 16, 2018
Q. Can I get enough vitamin D from sunlight, even if I live in a place with little sunlight during the winter?
A. Most people can make enough vitamin D from sun exposure during the summer, but for many, synthesis can be inadequate in the winter. A 2016 study led by researchers at the Centers for Disease Control and Prevention estimated that 14 to 18 percent of Americans have inadequate vitamin D, although what constitutes a healthy blood level is subject to debate.
Synthesis of vitamin D, which is critical for bone health, requires exposure to ultraviolet-B rays from the sun. In the summer, when the sun is directly overhead, vitamin D synthesis can be very efficient. For someone with light skin in a temperate climate at midday, “10 minutes a day of exposure to 10 percent of your body’s surface area, such as your arms and face, will give you what you need,†said Dr. Bess Dawson-Hughes, director of the Bone Metabolism Lab at the USDA Nutrition Center at Tufts University. Closer to the Equator, even less time is required.
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https://www.nytimes.com/2018/02/16/well/live/do-i-get-enough-vitamin-d-in-the-winter.html?rref=collection%2Fsectioncollection%2Fhealth&action=click&contentCollection=health®ion=stream&module=stream_unit&version=latest&contentPlacement=1&pgtype=sectionfront
