Value Village ／ Health
This answer is a draft. It stays unpublished until legal review and source verification are complete.
Upper limits for caffeine are presented differently from country to country, so conversations about it often talk past each other. Japan's public bodies have taken an unusual route: rather than setting a figure of their own, they present the assessments made overseas. If you have moved to Japan and are looking for "the Japanese limit", this is what you will find.
The Food Safety Commission of Japan (Cabinet Office) fact sheet "Caffeine in food" [食品中のカフェイン] (created 2011, updated 2018) presents the following as assessments by overseas bodies:
| Who | Guide |
|---|---|
| Healthy adults | up to 400 mg a day (5.7 mg/kg at a body weight of 70 kg) |
| During pregnancy | 200 mg a day or less |
| Children (3–10) and adolescents (10–18) | 3 mg per kg of body weight a day |
Excess intake is described as possibly causing dizziness, a raised heart rate, agitation, anxiety, tremor and insomnia.
[Verify] The figures are based on the Food Safety Commission fact sheet. Check against the original PDF before publication. If listing the caffeine content of individual drinks, take those figures from the same document.
Caffeine is also in tea, energy drinks and some medicines. Gyokuro (玉露, a high-grade shaded green tea) is described as containing more than coffee.
Constitution, body size, usual intake and any medicines you take all change how you feel it. 400 mg does not mean "safe for everyone".
Metabolism varies from person to person. For some people, a cup in the early evening affects the night.
Some products still contain small amounts. Check the label (in Japan, look for カフェインレス, kafein-resu, or デカフェ, dekafe).
A lower guide of 200 mg a day or less is given for pregnancy. Consult a doctor or pharmacist.
---
https://www.fsc.go.jp/factsheets/index.data/factsheets_caffeine.pdf
https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/0000170477.html
https://www.maff.go.jp/j/syouan/seisaku/risk_analysis/priority/hazard_chem/caffeine.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.
This is general information. Results vary from person to person and depend on your own conditions and surroundings.
Please decide for yourself, using your own judgement, whether any of this suits your situation. We cannot accept responsibility for any damage, loss or injury arising from following this article.
This article is not meant to diagnose or manage any specific medical condition. If you are worried about your health, see a doctor rather than relying on your own judgement.
Tell us if this has changed
Approved contributions keep the contributor's name, shown in five languages.
Other languages：日本語 ／ 简体中文 ／ 繁體中文 ／ 한국어
Value Village is not a government body. Always confirm procedures on the official site.
Written by Value Village from public sources. Nothing here is reproduced from another site.