Can you supplement calcium by sunbathing through glass？

　　The weather is cold in winter, and some people are afraid of the cold and don’t want to go out. They just sit on their balcony and bask in the sun through the glass, thinking that this can supplement calcium. Can you really supplement calcium by sunbathing through glass?

　　Sunbathing is to supplement vitamin D.

　　Cao Xuexia, deputy director of the Department of Endocrinology, xuanwu hospital, Capital Medical University, said that the main purpose of sunbathing is not to supplement calcium, but to supplement vitamin D. The main function of vitamin D is to promote intestinal calcium absorption, increase muscle coordination and prevent falls. When in the sun, ultraviolet rays reach the skin, and 7- dehydrocholesterol in the skin will gradually transform vitamin D. However, if you bask in the sun through the glass, the glass will block some ultraviolet rays, and the amount of ultraviolet rays will be obviously attenuated, which will affect the absorption of vitamin D and calcium.

　　Experts suggest that ultraviolet rays should be exposed to the outside world under the condition of adequate protection, and ultraviolet rays will be attenuated through glass, especially B-segment ultraviolet rays that stimulate the skin, which will affect the transformation of vitamin D and thus the absorption of calcium. If you need calcium supplement, most of the calcium still needs to be taken from food, such as milk or calcium tablets.

　　It is advisable to bask in the sun for less than 30 minutes.

　　Sunbathing through the glass really can’t promote the absorption of calcium, and it may even get sunburned. If you really can’t go out for activities, you must also open the window and let the sun directly contact your skin. "Shorts and short sleeves in summer, showing face and hands in winter" is the best choice.

　　It should be noted that the time spent in the sun is not as long as possible, and too long exposure may hurt the skin. Most people can spend 10-20 minutes in the sun every day. Children can spend a shorter time and the elderly can spend a longer time, but it is generally recommended to spend 30 minutes. If necessary, you can wear sunglasses to avoid eye damage caused by direct sunlight, and wearing a hat can avoid hair sunburn. After sunbathing, it is necessary to replenish water in time and vitamin C selectively to inhibit the production of melanin and prevent sunburn.