It is said that more sun exposure can supplement calcium. What is the principle?

Sunbathing can help people get vitamin D, which is also the main source of vitamin D. Ultraviolet rays in sunlight can promote 7- dehydrocholesterol in the skin to produce provitamin D3, which is converted into vitamin D3 through skin temperature, absorbed into the blood by lymphatic transport, and then generated into active vitamin D by hydroxylase in the liver and kidney. Vitamin D has a better name, called "sunshine vitamin".

The source of vitamin D3 contained in human skin is made by obtaining ultraviolet rays from sunlight and converted into vitamin D, which can help the human body absorb calcium and phosphorus and make the human bones grow strong and strong. The absorption of calcium is inseparable from vitamin D, so we must supplement enough vitamin D while supplementing calcium. The best way is naturally to bask in the sun. Of course, you can also directly choose calcium containing vitamin D, and at the same time you can supplement vitamin D. For pregnant mothers who are inconvenient to bask in the sun in winter, it is not necessary to take vitamin D and cod liver oil, and it is not easy to cause excessive intake of vitamin D.

In addition, in the process of basking in the sun, the infrared rays in the sun can penetrate through the skin and reach the subcutaneous tissue, which plays a role in keeping warm, dilating blood vessels and promoting blood circulation and metabolism of the whole body. This is also very beneficial to the absorption of calcium. Sunbathing is not the most direct and important way to supplement calcium, but it is indeed an indispensable way to supplement calcium. For the average person, the time from 6 am to 10 is most suitable for sunbathing. At this time, the infrared rays in the sun are strong and the ultraviolet rays are weak, which can play the role of promoting blood circulation and removing blood stasis; 4 pm to 5 pm is also the best time to bask in the sun, which can promote the absorption of calcium and phosphorus in the intestine, enhance physical fitness and promote normal calcification of bones. However, the sunshine time is longer in summer, and the heat wave is rolling at 4-5 pm, so the sunshine time can be slightly delayed. For those pregnant women, the body needs to bear the calcium needs of two people. It is enough to bask in the sun for half an hour every day in summer, and not less than 1 hour every day in winter.

You can't stay indoors all day, because your body is inconvenient. For developing children, the body needs a lot of calcium, and they are most vulnerable to calcium deficiency. So starting from two months, you should go outdoors to bask in the sun every day. 9 ~ 10 in the morning and 4 ~ 5 in the afternoon are suitable time to go out. The time to receive sunlight can be gradually extended from the first ten minutes to one hour. When the weather is not too hot, you can bask in the sun and stay in the shade for a while. Don't bask in the sun directly in summer, you can also get in touch with scattered ultraviolet rays in the shade. For the elderly who are prone to calcium deficiency, you can sunbathe before 9 am and after 4 pm, but it is best not to go out alone to sunbathe. If they fall asleep in the pleasant sunshine, they may catch a cold. Find a few companions and talk while walking. They are easily exposed to ultraviolet radiation.