Vitamin D is a nutrient necessary for maintaining daily health. Vitamin D can be produced in the body through sunbathing. However, some people who are highly beauty conscious may feel worried that exposure to the sun will increase the appearance of wrinkles and age spots.

This article explains the relationship between vitamin D and sunlight and the appropriate amount of sun exposure. We will also explain the effects of sunbathing in detail, so please refer to it.

Why sunlight is necessary for vitamin D production and how long to expose it to sunlight

Sunbathing has many benefits, including maintaining health and relaxing effects. From here, we will introduce the benefits of exposure to sunlight and its relationship with vitamin D.


●Why sunlight is necessary for the production of vitamin D

Vitamin D can be obtained through food, but it is also produced through exposure to sunlight. This property of vitamin D is very unusual because most vitamins cannot be produced by the body.

When the skin is exposed to ultraviolet rays, vitamin D is produced from a component called 7-dehydrocholesterol in the skin.

There are only a limited number of foods that contain vitamin D, so if you don't get enough sunlight, you may become deficient in vitamin D. Recently, the number of people who are deficient in vitamin D is increasing as more people work remotely and take precautions against UV rays. Therefore, it is important to consciously go outside and get some sunlight.


●Approximate time for exposure to sunlight

The amount of sunbathing required to produce vitamin D is approximately 15 to 30 minutes. The amount of sunbathing you need varies greatly depending on your region, weather, and season.

The following is the amount of sunlight exposure required to produce 5.5μg of vitamin D on a sunny day.

The Ministry of Health, Labor and Welfare's Dietary Intake Standards for Japanese (2020 Edition) sets the recommended intake amount of vitamin D at 8.5 μg and the tolerable upper limit at 100 μg for men and women over the age of 18.

If you live in the winter or in the north, you won't be able to produce enough vitamin D unless you spend more time in the sun. On the other hand, if you live in the summer or in the south, a shorter time may be sufficient.

【Quote】
“Dietary Intake Standards for Japanese (2020 Edition)” (Ministry of Health, Labor and Welfare)
https://www.mhlw.go.jp/content/10904750/000586553.pdf

Function of vitamin D produced by sunlight

Vitamin D is a component that helps calcium function and is considered important for maintaining health. It is especially recommended for people who want to improve their lifestyle habits.

Reasons and precautions to take in sunlight other than producing vitamin D

Sunbathing has been reported to have a variety of health benefits in addition to producing vitamin D. Here we will introduce why sunbathing is recommended and some precautions.

Reasons why you want to soak up sunlight

The three main effects you can expect from sunbathing are:


● Can reset your body clock

There are 24 hours in a day, but the human body clock is said to be approximately 25 hours long. If you live without sunlight, your body won't be able to adjust to the 24-hour cycle. Therefore, by sunbathing, your body clock is reset and you can lead a regular life.


● strengthen bones and teeth

Sunbathing allows your body to absorb calcium more efficiently. Therefore, it is also effective in preventing osteoporosis.


● stress relief

Sunbathing stimulates the secretion of serotonin, known as the happy hormone. It also has a relaxing effect and improves concentration.

Precautions when exposed to sunlight

If you are exposed to sunlight for a long time, you will get sunburn due to the effects of ultraviolet rays. The reason your skin turns brown is because it tries to protect itself from damage caused by ultraviolet rays. Excessive tanning can have negative effects on your health, so you should be careful.

In addition, strong ultraviolet rays destroy collagen and elastin, which keep the skin supple.
This can also cause sagging and wrinkles.

Sunbathing method for vitamin D production

If you want to efficiently generate vitamin D, be particular about how you sunbathe. From here, we will introduce some points about sunbathing.


● go outside and get some sunlight

If you want to produce vitamin D, you need to go outside and get some sunlight, not indoors. Ultraviolet rays are divided into two types: "UV-B" and "UV-A." UV-B is what produces vitamin D. Since UV-B does not pass through glass, no effect can be expected from indoor sunbathing.


● bathe without sunscreen

Many sunscreens inhibit vitamin D production when applied to the skin. The "Ultraviolet Environmental Health Manual 2020" published by the Ministry of the Environment states that using sunscreen with SPF 30 will reduce the amount of vitamin D produced by 5% or less.

If you are concerned about the effects of sunburn on your skin, it is best to apply sunscreen only to your face.

【reference】
“Ultraviolet Environmental Health Manual 2020” (Ministry of the Environment)
https://www.env.go.jp/content/900410650.pdf

Get rid of vitamin D deficiency by sunbathing

In this article, we explained the relationship between vitamin D and sunlight and the appropriate amount of sunbathing.
Sunbathing time should not be too long or too short. It is important to expose yourself to sunlight for the appropriate amount of time depending on your region and weather. Please use this article as a reference to take advantage of sunbathing and use it to maintain your health.

Article supervision

Director of Mizutani Dermatology Clinic
Professor Haruko Mizutani
Mizutani Dermatology Clinic

Graduated from Tokyo Medical University. After working in the dermatology department of Tokyo Medical University Hospital and the Tokyo Cosmetic Dermatology Clinic, he opened Mizutani Dermatology Clinic in 2012.

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