Sunbathing vitamin D supplementation: The top 6 most common questions doctors ask

People with osteoporosis use anti-osteoporosis medications while deciding whether vitamin D supplementation is needed based on vitamin D levels. Vitamin D supplementation is done in two ways, one is by taking drugs containing vitamin D or by sun exposure.

In the outpatient clinic, we usually instruct patients to take oral medication, but also recommend them to bask in the sun, today, the office will often be asked a few questions, the author to make a simple summary, to share with you.

Sunshine Solar Vitamin D Supplement?

About 80% of the vitamin D of human origin is synthesized in the epidermis of the skin and only 20% is ingested from food. Under the action of medium-wave ultraviolet UVB, 7-dehydrocholesterol in the skin is converted into vitamin D by non-enzymatic photosynthesis reactions, which enter the blood circulation from the skin.

Vitamin D is converted to 25-(OH)D under the action of liver 25-hydroxylase, and then under the catalytic action of renal 1α-hydroxylase, 1,25-(OH)D is produced, which is an activated form of vitamin D.

In addition, the cereals we eat contain ergosterol, which is also converted to vitamin D by ultraviolet radiation after being absorbed by the human body.

Since vitamin D and vitamin D are important substances for bone metabolism, which can promote the absorption of calcium in the small intestine and promote the formation of bones, it is said that sunshine supplements vitamin D can also supplement calcium, prevent and improve osteoporosis.

What time is the sun?

In a day, there are two time periods that are most suitable for basking in the sun, the first period is from 9 a.m. to 10 a.m., and the second period is from 4 p.m. to 5 p.m., in these two time periods, there are more A beams in ultraviolet rays, which is a good time to reserve vitamin D in the body.

However, the concept of "optimal sun exposure" is not entirely reliable, and it is simpler and more effective to use the "shadow principle" to choose the time period for sun exposure - it is not advisable to come out to bask when the length of the shadow is shorter than the height.

In summer, due to the strong ultraviolet rays, choose to exercise outdoors in the early morning or in the evening when the sun is not too strong.

What parts are sunburned?

Some experts pointed out that the sensitivity of the skin of the trunk to the sun is higher than that of the limbs, the sensitivity of the skin of the upper limbs is higher than that of the lower limbs, the sensitivity of the skin on the flexion side of the limbs is higher than that of the extensor side, and the head, face, neck and hands and feet are the least sensitive to ultraviolet rays.

Therefore, we can choose to fully expose the parts with poor sensitivity, wear short-sleeved shorts in the summer, expose the head and neck in the winter, and apply sunscreen products to the sensitive parts to protect the skin. Wearing sunglasses can prevent direct sunlight from causing eye damage.

How long does it last?

In winter and spring, expose the face and upper arms to the sun for 10 to 30 minutes, while in summer, due to strong ultraviolet rays, there are more exposed parts, and receiving direct sunlight for 5 to 10 minutes, 2 to 3 times a week, can make the body produce enough vitamin D.

The vast majority of people can be basking in the sun for 10 to 20 minutes a day, children are shorter, the elderly are longer, but it is generally recommended to control it within 30 minutes. People living at high altitudes and chronically low-oxygen deprivation need to spend 30 to 60 minutes a day in the sun.

Is sunbathing through the glass effective?

Basking in the sun through the glass will greatly reduce the effect of calcium supplementation, because the penetration of medium-wave ultraviolet UVB is relatively poor, and a piece of paper can block UVB, not to mention thick glass.

Ordinary white glass can probably penetrate 9% of ultraviolet light below 320 nm, while single silver low-radiation insulating glass has a transmittance of basically 0%.

Therefore, basking in the sun through the glass at home is almost ineffective, because the transmittance of medium-wave ultraviolet rays will be greatly reduced, which will affect the vitamin D required by the body to synthesize calcium supplementation.

The best place to bask in the sun is outdoors, for various reasons must be basked indoors, but also be sure to open the window, let the sun directly contact the skin.

How to dry to avoid tanning and sunburn?

Why does the skin tan?

Tanned skin is a long-wave ultraviolet UVA, UVA is called "indoor ultraviolet light", can be refracted through the glass into the room, umbrellas, hats, clothes are not its opponents.

When the sun shines on the skin, it can activate the melanocytes located in the basal layer of the epidermis, melanocytes contain pigment particles, catalyzed by tyrosine to produce melanin protein, tyrosinase transfer it to keratinocytes, the more melanin protein is transferred to keratinocytes, the darker the skin, and because UVA can penetrate deep into the dermis layer of the skin to damage collagen and elastic fibers, it will also cause skin aging.

Why does the skin get sunburned?

Sunburned skin is medium-wave ultraviolet UVB, UVB is called "outdoor ultraviolet light", umbrellas, hats, clothing, glass will block a part of the UVB.

Due to its high activity, it can produce strong photodamage to the skin, the dermal blood vessels at the irradiated site are dilated, the skin can appear red, swollen, blisters and other symptoms, and the skin will appear erythema, inflammation, skin aging for a long time, and in severe cases, skin cancer can be caused.

But it should be emphasized that the promotion of vitamin D synthesis in the skin is also medium-wave ultraviolet UVB. Short-term non-sensitive parts exposed to the sun is safe for the skin, must not be bathed in the sun for a long time, so choose the right time period, the right part, the right length of time to avoid skin sunburn tanning.

There are also people who worry that the sun will be excessive, in fact, this worry is superfluous, the synthesis of vitamin D under sunlight exposure is synthesized by the body on demand, will not lead to overdose or poisoning.

In addition, light skin color is more synthetic than dark skin color people synthesize vitamin D, because dark skin, especially black skin, can block ultraviolet rays from entering the dermis layer of the skin, affecting the synthesis of vitamin D, and dark clothes can protect against suns.

brief summary

Vitamin D is known as "sunshine vitamin", the human body can be synthesized when basking in the sun, has the role of maintaining human bones and teeth, and has a positive significance in protecting cardiovascular and cerebrovascular health, cancer prevention and anti-cancer, so we must use the free resources given to us by nature - sunlight to drive away diseases.

Nowadays, there are more and more people sitting in the office, the sun is not limited to the elderly and children, the incidence of osteoporosis has a clear trend of rejuvenation, and young and middle-aged people should also join the army of sunbathing.

Planning | Jiang Eleven

This article was first published on Lilac Garden's professional platform: Endocrine Time