In early spring and March, everything recovers. Shoots emerge from the branches, everything is full of vitality, and we should also follow the laws of nature and go out to bask in the sun! Exposure to the sun can help synthesize vitamin D, which in turn promotes calcium absorption and prevents osteoporosis. But long-term sun exposure will lead to aging, between the dilemma, how to choose? To this end, the reporter interviewed Dr. Huang, the attending physician of the Department of Endocrinology of Zhongda Hospital Affiliated to Southeast University, who pointed out that basking in the sun is a "technical work" and it is very important to learn methods.
Ultraviolet rays, the body loves it and fears it.
The main source of UV light in nature is the sun, and the body loves and hates it. Dr. Huang introduced that before basking in the sun, it is necessary to understand the sun. Ultraviolet rays in sunlight are divided into UVA, UVB, and UVC according to their different wavelengths. Among them, UVC cannot reach the earth's surface, and the first ones that can be contacted are UVA and UVB.
UVB refers to ultraviolet rays, accounting for 5-10%, which can only reach the ** epidermal layer, but its energy is higher. **After being exposed to ultraviolet (UVB) rays, it will cause redness and sunburn, which can act on ** to help synthesize vitamin D. However, ordinary glass can block UVB, so it has no effect when basking in the sun through glass.
Basking in the sun, the right method is better.
According to Dr. Huang, latitude, altitude, air pollution, and time of day outside can all affect the effectiveness of sun exposure. In order to improve the effect of sun exposure, it is recommended to go out appropriately and bask in the sun when the UV index is 3, but it should be noted that do not bask in the sun through the glass. Generally speaking, 11:00-15:00 is the best time to bask in the sun in spring, summer and autumn. At this time, it is better to expose the face and upper arms to sunlight for 5 to 30 minutes (depending on multiple factors), 3 times a week. It should be noted that it is not recommended to evaluate the synthesis of vitamin D by whether or not to tan when in the sun, because tanning is the function of UVA. In addition, direct sunlight should not be exposed to the strongest sunlight to avoid inducing cancer.
Sunscreen, did you choose the right one?
Many people are worried about tanning and aging while basking in the sun. Sunscreen is an important measure to prevent pigmentation and photoaging, but are you worried that applying sunscreen will affect the synthesis of vitamin D, and then affect the absorption of calcium? Huang points out that the SPF of sunscreens includes PA and SPF. PA stands for the ability to defend against UVA, protection from tanning and aging. SPF stands for the ability to defend against UVB rays and sunburn, but it also hinders vitamin D synthesis. Therefore, it is recommended to choose sunscreen products with a high PA and low SPF. People who already have vitamin D deficiency can appropriately reduce the use of sunscreen and the chances of using it.
These are the factors that affect vitamin D synthesis.
Sunlight can help the body synthesize vitamin D, which can promote the absorption and utilization of calcium and phosphorus by the body, which is conducive to bone health. Most of the vitamin D needed by the body comes from sun exposure, and a small amount comes from food. Age is also an important factor affecting vitamin D synthesis, aging ** produces less vitamin D than younger **, and aging kidneys also affect the further activation and role of vitamin D in the body. In addition, smoking, obesity, skin color, genetic factors, and long-term use of drugs (phenytoin, phenobarbital, rifampicin) can also affect vitamin D levels.
At present, more and more young people have less time to go out and lack of sun exposure due to lifestyle and other reasons, and vitamin D deficiency has become one of the global public health problems. In Asia, about 75% of the population is vitamin D deficient or insufficient. Therefore, it is important to spend time in the sun regularly and scientifically. In addition, if you want to know whether there is vitamin D deficiency, you can go to a regular hospital to have a blood test of 25OHD. Vitamin D deficiency can be improved by oral vitamin D preparations under the guidance of a physician if necessary. (Wang Qiancheng Shouqin).