Value Village ／ Health
This answer is a draft. It stays unpublished until legal review and source verification are complete.
The claim that "sunscreen leaves you short of vitamin D" is raised in many countries as a counter to sun-protection campaigns. In Japan the 2025 Dietary Reference Intakes raised the adequate intake for vitamin D, and interest has grown.
| Item | Detail | Source |
|---|---|---|
| Adequate intake (adults) | 9.0 μg/day (raised from 8.5 to 9.0 in the 2025 edition) | Dietary Reference Intakes for Japanese (2025 edition) |
| Tolerable upper intake | 100 μg/day | Same as above |
| Actual intake (age 20 and over) | About 6–7 μg (higher in people who eat fish) | National Health and Nutrition Survey |
| Sunlight needed | Clear July day at noon, face and backs of both hands: about 3–4 minutes in Tsukuba, about 5–6 minutes in Sapporo for the equivalent of 10 μg. At noon in December: about 76 minutes in Sapporo, about 8 minutes in Naha | National Institute for Environmental Studies (2013) |
| Foods | Salmon, 1 fillet (80 g) about 26 μg; Pacific saury (sanma), 1 fish about 16 μg; kikurage wood-ear mushroom (2 g dried) about 1.7 μg; dried shiitake (3 pieces) about 0.4 μg; 1 egg about 1.3 μg | Food composition tables |
[Verify] Check the adequate intake against the 2025 Dietary Reference Intakes, the sunlight exposure times against the National Institute for Environmental Studies release (2013), and the food values against the Standard Tables of Food Composition in Japan (8th revised edition).
Everyday exposure (face, hands, a few minutes on the commute) plus food is enough. The Ministry of the Environment's position is to recommend UV protection while covering vitamin D from food and everyday exposure.
Production levels off at a certain amount, and any further UV is only a burden on the skin. In summer, a few to ten-odd minutes is enough.
UVB, the part of sunlight involved in making vitamin D, barely passes through window glass. Little is produced sitting by a window indoors.
There is a tolerable upper intake of 100 μg, and excess causes hypercalcaemia (too much calcium in the blood). Exceeding the limit with a normal diet plus a supplement is rare, but for high-dose supplements, ask a doctor or pharmacist.
Fish consumption is falling, and younger generations are generally described as taking in less than the adequate intake. Fish two or three times a week, mushrooms and eggs are the realistic way to get enough.
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https://www.mhlw.go.jp/stf/newpage_44138.html
https://www.nies.go.jp/whatsnew/2013/20130830/20130830.html
https://www.env.go.jp/chemi/uv/uv_manual.html
⚠️ Editorial note: the source URLs above were identified by search. Our working environment cannot reach go.jp domains, so the contents have not been checked against the text. Verify every source before publication and record who checked it and when.
What we share here are ideas and everyday practices passed down among people living in Japan, together with general information drawn from public sources. They are not official recommendations, and they are not professional instruction. Practices vary between households and regions.
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