Now that spring is bright, many people choose to go outdoors to bask in the sun, not only to harvest a good mood, but also to "supplement calcium".
For office workers who leave early and return late, they can only have intimate contact with the sun through the glass window.
Experts interviewed
You Changxuan, chief physician of the Department of Oncology, Nanfang Hospital, Southern Medical University
Lu Peiwan, deputy chief physician of the Center for Preventive Treatment of Diseases of Henan Provincial Hospital of Traditional Chinese Medicine
Yang Yanyan, Deputy Chief Physician of Rehabilitation Medicine Center, Peking University Third Hospital
Exposure to the sun through glass does not supplement calcium
People say that calcium supplementation in the sun is actually vitamin D.
There are two main sources of vitamin D in the body, one is synthesized by chemicals in the skin under sunlight or ultraviolet radiation; The second is obtained through meals.
Vitamin D is activated by the liver and kidneys to become active vitamin D, which plays an important role in regulating bone growth and development; It can promote the absorption of calcium and phosphorus in the intestines and kidneys; or directly act on bone, promoting bone formation and bone mineralization; It can also act on skeletal muscle and strengthen muscle strength.
Is it useful to bask indoors through glass?
Unfortunately, there is basically no effect. Although it is true that UV rays are exposed to glass, not all UV rays promote vitamin D production in the skin.
Ultraviolet rays are divided into: UVA, UVB, UVC.
UVC
Almost all of them are absorbed by the ozone layer and have little effect on us.
GRAPE
It is not easily blocked by glass, and can irradiate the body through glass, which will accelerate skin aging and has no effect on promoting the production of vitamin D in the skin.
UVB
It can promote the production of vitamin D in the skin, but it is blocked by glass. Therefore, by basking in the sun through glass, the skin cannot produce vitamin D and cannot promote calcium metabolism.
How sunlight makes people "prolong" their lives
In addition to promoting calcium absorption, sun exposure has many unexpected benefits.
Prevention of osteoporosis
Sun exposure is beneficial to the body's production of vitamin D and promotes the absorption and utilization of calcium and phosphorus. Conversely, it can lead to vitamin D deficiency and increase the risk of osteoporosis.
Protect the mind and brain
Vitamin D regulates blood pressure, improves heart function, and reduces the risk of heart disease and stroke. Adequate vitamin D intake can reduce the risk of early death in patients with cardiovascular disease by 30%.
Regulates blood pressure
Sun exposure regulates blood pressure by inhibiting the activity of the renin-angiotensin system in the body, preventing it from being too high or too low.
Improves mood
Seeing too little sunlight will lead to increased melatonin, aggravate drowsiness, fatigue; It also inhibits the production of "happy hormones" in the brain. When exposed to the sun, the body's adrenaline, thyroxine and gonadoxine secretion levels will be increased, which can help improve mood.
Reduces the risk of cancer
Research from Queen's University in Canada shows that getting enough sun exposure in youth reduces the risk of breast cancer by at least 17%. The British Medical Journal published an article saying that vitamin D levels in plasma are inversely correlated with cancer risk.
Prevention of dementia and stroke
Researchers in Australia have found a direct link between dementia and stroke and vitamin D deficiency, and that more sun exposure can help prevent dementia and stroke.
Stabilize blood sugar
Research by the National University of Malaga in Spain found that low levels of vitamin D due to insufficient sun exposure can increase the risk of obesity and type 2 diabetes.
In the view of Chinese medicine, it is important to bask in the sun in spring. At this time, the weather turns from cold to warm, and the yang energy in the human body begins to rise. Basking in the sun can warm the yang qi in the body, which is one of the most direct and effective ways to replenish yang qi.
4 "degrees" of sun exposure
If you have the following symptoms, it may be that your body is prompting you to bask in the sun:
Inflammation or infection often occurs, and inflammation is not easy to get better.
Feeling depressed, especially on rainy days and winter.
Always tired.
Joint pain, weakness in the extremities.
Feel muscle pain.
There are a few things to pay attention to when basking in the sun:
Choose the time according to the time
How do I find the best time to bask in the sun? You can judge by looking at the shadow length:
◎ The shadow is 2 times and above height, the ultraviolet index is the safest, and no protection is required;
◎When the shadow is in the range of 1~2 times the height length, the duration of sun exposure is controlled for about 20 minutes;
◎ The shadow is shorter than the height, and ultraviolet rays may cause damage to the skin within 30 minutes;
◎ The shadow length is less than half the height, and ultraviolet rays can damage the skin within 15 minutes.
10~20 minutes each time
The amount of time spent in the sun varies by altitude, region, season, ethnicity, individual, and location. Most people can meet the needs of the body by basking in the sun for 10~20 minutes a day.
People with dark skin should spend more time in the sun than people with light skin, children are shorter, and the elderly are longer.
Try to get outdoors
The health benefits of sun exposure are a combination of exposure to the sun and outdoor activities. Outdoor activities can also help improve mood.
Having to bask indoors, windows should be opened so that the skin comes into direct contact with the sun.
Bare skin direct tanning
In general, the skin of the trunk is more sensitive to sun exposure than the extremities, the sensitivity of the skin of the upper limbs is higher than that of the lower limbs, the sensitivity of the skin inside the limbs is higher than that of the outside, and the head, face, neck, hands and feet are the least sensitive to ultraviolet rays.
Shorts and sleeves in summer, face and hands exposed in winter, and forearms, hands, calves and other parts exposed in spring when the temperature is right.
Reminder:
People living in high-altitude areas such as Qinghai and Tibet, as well as those who have been working outdoors for a long time, should pay attention to sun protection.
Going to the beach to "sunbathe" means receiving a lot of sun exposure in a short period of time, which can easily lead to sunburn, and should be protected from the sun.
People with photoallergies and those who are taking photosensitizing drugs such as sulfonamides and quinolones should be strictly protected from the sun.
Frail, high blood pressure and heart disease patients should do what they can and should not be exposed to the sun for too long. ▲
Editor of this issue: Wang Xiaoqing