ビタミンDサプリメントは日焼け対策ばっちりな方こそ内服を | 日本を代表する美容健康再生医療のクリニック

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Aiya Hayama

2025.08.12

Vitamin D supplements are especially recommended for those who take thorough precautions against sunburn.

Supervising Physician

Board Certified Dermatologist, Japanese Dermatological Association Aiya Hayama

As an Assistant Professor, Associate Ward Director, and Chief of Dermatopathology at the university hospital dermatology department, I deepened my expertise through academic presentations and paper publications both domestically and internationally. I have handled a wide range of treatments, from birthmark therapy in children to adult pigmentation concerns, utilizing various lasers and injection therapies, while also contributing to community healthcare. Through encountering numerous cases, I strongly felt the potential and necessity of aesthetic medicine, resolving to pursue further expertise. Building upon my solid dermatological knowledge and meticulous diagnostic skills, I value treatments that gently support each individual's skin while bringing out its inherent beauty.

Vitamin D supplements—I think some products often combine it with vitamin C.

Are you taking measures to protect yourself from sunburn?

I am Dr. Aya Hayama, a board-certified dermatologist.

How to Use Sunscreen

First, regarding how to use sunscreen.

SunscreenSPF, PA valueI think there is.

SPF primarily measures the level of protection against UVB rays, which cause sunburn. An SPF of 30 means it can extend the time until sunburn occurs by approximately 30 times.

The PA value indicates the level of protection against UVA rays that penetrate deep into the dermis, with a higher number in the + notation signifying stronger effectiveness.

Sunscreen, like topical medications,Sufficient amount (for the face: 500-yen coin size for liquid, two pearl-sized drops for cream, two and a half sprays for spray)if possibleevery three hoursIt only becomes effective when reapplied. If makeup products tend to build up too thickly, they should be applied thoroughly as a base. Make good use of makeup products for reapplication.

Physical sun protection is also effective, and we recommend using sun umbrellas, UV-blocking arm covers, and sunglasses to help prevent conditions like cataracts and age-related macular degeneration.

Vitamin D deficiency

Vitamin D is found in foods such as fish and mushrooms, but it is easy to become deficient relying solely on dietary sources, soModerate sun exposure is essential for skin replenishment.Japanese people are often deficient in vitamin D to begin with, and exposure to ultraviolet rays is also necessary to activate it.

In countries at high latitudes like Canada and Scandinavia, where the sun doesn't rise very high, sufficient vitamin D cannot be produced through skin exposure to sunlight alone, especially during winter. To prevent bone-related diseases, taking vitamin D supplements is essential. Conversely, in countries like Japan located at mid- or low-latitudes, the sun's angle is sufficiently high. It was traditionally thought that vitamin D deficiency rarely occurs as long as people go outside and live a lifestyle that involves regular exposure to sunlight. 　

However, since around the 2000s, reports have increased indicating that vitamin D deficiency or insufficiency is becoming more common among Japanese people, particularly young women, leading to a rise in bone-related disorders such as bowlegs, rickets, compression fractures, and osteoporosis.

In fact, this coincided with the period when information spread widely about ultraviolet rays being harmful to the skin and, in the worst cases, causing skin cancer, a trend that began with the discovery of the Antarctic ozone hole in 1985.

In fact, the instruction "Let your baby sunbathe" previously found in the "Maternal and Child Health Handbook" was changed to "Let your baby breathe fresh air" after 1998.*1

It's still fresh in our memory how, in this age of overabundance, excessive restrictions on sun exposure for children and dietary measures to avoid allergies led to a problem of rickets—a condition where bones become brittle due to vitamin D deficiency.

The Ministry of the Environment, the Japanese Society for Vitamin Research, and other organizations recommend 30 minutes of sunlight exposure daily.‼️ (Just the palm is fine)

References and Citations*1

https://www.nies.go.jp/kanko/kankyogi/79/10-11.html

If you're someone who takes perfect sun protection measures👌, you probably think spending even 30 minutes in UV rays is unthinkable... so please make sure to take vitamin D supplements to compensate.

In regions like Northern Europe with limited daylight hours, vitamin D supplementation is commonplace, so we recommend it alongside sunscreen measures.