Expert: Excessive sun protection is not advisable. Face the "grilling" of sunlight to test the ability of "facial kini" to appear frequently | vitamins | sunlight

With the continuous rise of temperature, people's attention to sun protection is also increasing. The reporter noticed that there are over 7.66 million notes related to "sun protection" on Xiaohongshu; The topic of "sunscreen" on Tiktok has been broadcast as many as 30.78 billion times; Various bloggers are constantly bombarded with evaluation videos related to sunscreen.

Faced with the sun's "baking" test, there are endless products for sun protection from the face to the body, and even hair. The reporter searched various e-commerce platforms and found that ordinary sunscreen equipment such as sunscreen, sunscreen caps, sunscreen sleeves, and sunscreen clothes have become commonplace. "Face kini" like sunscreen masks and "all-round protection" long one-piece sunscreen clothes have also appeared. Many people have finished equipping themselves, and almost only two eyes are exposed from top to bottom.

But is it really correct to be so sun proof?

Excessive sun protection is not advisable

Ms. Zhang, 28 years old, has been experiencing back pain and soreness for the past year. After undergoing a series of examinations at a tertiary hospital in Beijing, doctors ruled out related diseases such as lumbar disc herniation and determined that her symptoms were caused by osteoporosis. Last year, a Ms. Lin from Zhejiang also suffered from osteoporosis due to excessive sun protection. This incident became a hot topic and sparked widespread discussion.

According to Ms. Zhang, she has high requirements for fair skin and pays great attention to sun protection. Every time she goes out, she uses a beekeeper like sunscreen equipment, and even applies sunscreen indoors. Under the doctor's advice, she only applies sunscreen when going out now and deliberately sunbathes outdoors every week.

Sunscreen mainly protects against ultraviolet rays. Medium frequency ultraviolet radiation, abbreviated as UVB, is a type of ultraviolet radiation with a wavelength of 320-280 nanometers. Prolonged exposure to the skin can cause redness, inflammation, and skin aging, which should be carefully prevented; Low frequency long wave ultraviolet radiation, abbreviated as UVA, is a low-frequency ultraviolet radiation with a wavelength of 400-315 nanometers. Long wave ultraviolet radiation has strong penetration into clothing and human skin, can reach deep in the dermis, and can act on melanin in the epidermis, making the skin black. Its effect on the skin is slow, and long-term accumulation can lead to skin aging and serious damage.

Just like plants need sunlight to thrive, so do humans. Clothing and sunscreen not only block ultraviolet rays, but also inhibit the ability of UVB. However, the skin synthesizes vitamin D precisely at the wavelength of UVB. Assuming we apply sunscreen to our skin, it greatly reduces our ability to synthesize vitamin D.

A survey conducted in Shanghai targeting more than 20000 people showed that the proportion of people with vitamin D deficiency and deficiency was as high as 86.85%. The vitamin D deficiency rate is highest in the 18-29 age group, and vitamin D deficiency is very common in young women. This may be closely related to a lack of outdoor activities and excessive sun protection.

The fact is that Ms. Huang has been feeling short of sleep lately. She has been sleeping for 12 hours on weekends and often experiences leg cramps in the middle of the night. She immediately went to the hospital's endocrinology department for a blood test and found that her vitamin D level is only 5.7ng/ml, while the normal range of vitamin D should be between 30ng/ml and 100ng/ml.

Ms. Huang said that she is completely resistant to sunlight in her daily life. She not only needs to apply sunscreen every day, but also wears a one-piece sunscreen suit. This did make my skin a little whiter, but I didn't expect it to cause harm to my body.

Xue Ke, a doctor in the dermatology and venereology department of China-Japan Friendship Hospital, said that excessive sunscreen will indeed lead to a lack of vitamin D, which will lead to increased bone loss, osteoporosis and increased risk of fracture.

Some people may say that there are vitamin D supplements available on the market now, and I don't want to sunbathe, but can't I just take vitamin D supplements orally every day?

Xue Ke stated that taking oral vitamin D cannot replace the health benefits of synthesizing vitamin D from sunlight. Studies have shown that vitamin D synthesized by the skin can bind 100% to vitamin D protein, while oral vitamin D can only bind 60%. "So, taking oral vitamin D combined with sun exposure can effectively supplement calcium."

The symptoms of vitamin D deficiency are often insidious, and if not checked, many people may not realize their vitamin D deficiency.

In fact, vitamin D not only helps with calcium absorption, but also promotes skin cell growth, differentiation, and regulates immune function. When exposed to the sun, the secretion of melatonin decreases, which can improve one's mood and enhance the body's immune system. On the contrary, it is prone to mental depression and decreased resistance. In addition, a research team from Huashan Hospital affiliated with Fudan University and Qingdao Municipal Hospital published a study in the Journal of Internal Medicine of the British Medical Commission, suggesting that moderate exposure to sunlight can reduce the risk of dementia.

If the outdoor temperature is very high in summer and you cover yourself too tightly, it is likely to cause heatstroke and heat rash.

UV rays have strong power, so sun protection is necessary

Of course, the harm of inappropriate exposure to sunlight should not be underestimated. The well-known medical journal New England Journal of Medicine once published a case: a truck driver with 28 years of driving experience, due to his left face being close to the car window and receiving more sunlight, over time, his left face has significantly more wrinkles, thicker and more relaxed skin, and his aging condition is more severe compared to his right face.

The power of visible ultraviolet rays: While openly tanning you, secretly aging you.

Excessive ultraviolet radiation can damage skin cells, accelerate pigment synthesis, and disrupt the moisturizing effect of the skin. The skin will become dry, and the elastic fibers of the dermis will be damaged, promoting the formation of fine lines.

Xue Ke stated that excessive ultraviolet radiation may cause various skin problems. In summer, prolonged exposure to ultraviolet radiation enhances the skin's instinctive defense function, with a large amount of pigment particles concentrated in the basal cell layer of the epidermis to resist ultraviolet radiation. This can cause the skin to become darker, known as "tanned". Especially for women, there are often many pigmented spots, freckles, and melasma on the face.

After being continuously exposed to sunlight for several hours, some people may experience diffuse erythema on their skin, with superficial blood vessels dilating and congestion, and in severe cases, blisters. Long term exposure to sunlight can lead to skin diseases such as sun induced dermatitis and pigmented skin cancer.

The ultraviolet rays in sunlight can not only cause skin reactions, but also lead to keratitis, retinitis, cataracts, and macular degeneration of the fundus. For people who suffer from certain diseases and take photosensitive drugs and food, the harm caused by light exposure is more pronounced.

In addition, Dr. Xue Ke pointed out, "For beauty seekers who have already started optoelectronic medical beauty treatment, more attention should be paid to sun protection to prevent pigmentation after treatment."

How to Scientifically and Effectively Sunscreen

The ABC principle of sun protection advocated by the World Health Organization: A - Avoid, avoid being exposed to sunlight, is the best sun protection; B - Block, covering, preferred clothing, hats, umbrellas, and other "hard sun protection"; C-Cream, sunscreen, is used to supplement when A and B cannot meet the sun protection needs.

Based on this principle, we can rank scientific sun protection:

Firstly, outdoor activities should pay attention to avoiding high UV index periods such as noon. When working in areas with high UV index such as high plateaus, beaches, snowy areas, and around curtain wall glass, it is advisable to choose activities under tree shade or on the shaded side of buildings, avoiding direct sunlight with high intensity.

If exposed to strong ultraviolet rays for a long time and in a location, wear long sleeved clothing, sunglasses and a sun hat, and use high magnification sunscreen. If necessary, you can use a waterproof and sweatproof sunscreen, and at the same time, you can use spray sunscreen products to facilitate the timely spraying of the whole body.

Secondly, use sunshades, sun hats, and sunscreen clothing correctly. These sunscreen products are all physical sunscreen, effective, cost-effective, and reusable, making them our preferred measure for sun protection. It is particularly important to note that for sensitive skin, physical sunscreen is safer than chemical sunscreen.

Finally, applying sunscreen should be done with caution and in moderation. Before going out every day, you can check the weather forecast. If the UV intensity does not exceed 2, you can also avoid applying sunscreen outdoors. When choosing sunscreen products, it is important to consider the SPF and PA values. The SPF value represents a time range in which ultraviolet radiation does not harm the skin, and the PA value represents the product's ability to defend against long wave ultraviolet radiation with a "+" number. But these two indicators are not necessarily better. The larger the number, the worse the breathability, and the greater the burden on the skin. As for daily commuting, if the sunshine time does not exceed half an hour, applying low magnification sunscreen is sufficient.

For office workers, they work indoors almost all day and have no opportunity to be exposed to sunlight for extended periods of time. Occasional brief outdoor activities do not require strict precautions.

In addition to severely damaged sensitive skin, Xue Ke suggests exposing the skin to direct sunlight for 0.5-1 hour before 10am and after 4pm every day. At this time, the sunlight is not "toxic", allowing the body to receive sunlight while avoiding sunburn.

After applying some low magnification sunscreen on the face and neck, leave your arms or legs aside and choose a period of mild sunlight for sunbathing, which will better ensure the basic sun exposure needs of the body. However, photosensitive patients who are taking photosensitive drugs such as sulfonamides and quinolones should follow the doctor's advice to take proper sun protection.