I don’t seem to have seen a lot of human research on this.
Because different people are at different latitudes and work outdoors at different times, the sunscreen products used and the time of use are different. I don’t think it’s enough if it’s just a clinical study of hundreds or thousands of people. At least China needs to select a few cities from different regions, and test it in rural cities. At least tens of thousands of people are required to study these influencing factors.
But for non-human testing I saw such a paper a few years ago.
It is assumed that the damage of ultraviolet rays to the human body is through the production of free radicals (this is of course not completely correct). How many free radicals are produced to be harmful to the skin?
In 2014, Zastrow, Doucet, and Al defined the free radical threshold (FRTV) as ~3.5 × 10 rad/mg. Only when this limit is exceeded will there be harmful effects on the skin.
Then the value is also a bit awkward, almost close to the value of vitamin D production.
(This is like the drug retinoic acid. Its single-use effective concentration is almost the same as its irritant concentration. Even according to cosmetics (this retinoic acid is a prescription drug), generally speaking, if the adverse reactions should be controlled below 1%, 0.025 The % concentration of A acid has a high stimulation rate. Therefore, it is not recommended to use A acid as a skin care product.)
Of course, the above experiment also has flaws. But as far as this study is concerned, if we do a good job of sun protection, it does have the potential to affect the body’s synthesis of vitamin D.
I went to a medical examination with Sister Xiao before, and the doctor said at that time that the lack of vitamin D in women’s blood tests in recent years has been increasing. I wonder if everyone is doing a good job of sun protection.
Manual forehead. . . .
The doctor is guessing, but this guess is not completely unreasonable.
So, personally,
First: a physical examination every year is really important.
Second: Do not use sunscreen blindly. The ABC principle is important.
I like this one!
Third, eat more vegetables, rest more, and stay up too late (staying up late will also affect the synthesis of vitamin D). If you find vitamin D deficiency in the physical examination, you can buy some health products to eat. If you don’t have a physical examination, you can also eat it, but it is recommended to eat less , such as twice a week. Don’t eat it every day.
Source: Zhihu www.zhihu.com
Author: Yan Yuxiao
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Further reading:
How does sunscreen affect vitamin D?
How to find the balance between being tanned and being in the sun for calcium absorption?
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