Thiamin (B1) upper limit: how much is too much per day?
No tolerable upper intake level (UL) has been set for thiamin (B1), for adults or for any other life stage in the National Academies tables. The National Academies found too little data on adverse effects to set one.
Every life stage
| Group | Age | RDA or AI mg/day | UL mg/day |
|---|---|---|---|
| Male | 14–18 | 1.2 RDA | Not set |
| Male | 19–30 | 1.2 RDA | Not set |
| Male | 31–50 | 1.2 RDA | Not set |
| Male | 51–70 | 1.2 RDA | Not set |
| Male | 71+ | 1.2 RDA | Not set |
| Female | 14–18 | 1 RDA | Not set |
| Female | 19–30 | 1.1 RDA | Not set |
| Female | 31–50 | 1.1 RDA | Not set |
| Female | 51–70 | 1.1 RDA | Not set |
| Female | 71+ | 1.1 RDA | Not set |
| Pregnancy | 14–18 | 1.4 RDA | Not set |
| Pregnancy | 19–30 | 1.4 RDA | Not set |
| Pregnancy | 31–50 | 1.4 RDA | Not set |
| Lactation | 14–18 | 1.4 RDA | Not set |
| Lactation | 19–30 | 1.4 RDA | Not set |
| Lactation | 31–50 | 1.4 RDA | Not set |
RDA = Recommended Dietary Allowance; AI = Adequate Intake, used where there is not enough data for an RDA. UL = Tolerable Upper Intake Level. “Not set” means the tables give no value. Ages under 14 are in the National Academies tables and are not covered here.
What counts toward the limit
Without a UL there is no official daily maximum to compare against. A missing UL means the data were not enough to set a number, not that every amount has been shown to be safe.
Table footnote, as recorded in Ceiling’s data: “No UL has been established owing to a lack of data on adverse effects.”
How Ceiling uses this
Ceiling still adds up every supplement you scan and shows your daily thiamin (B1) total, marked “No limit set”. It counts supplements only, not food. Ceiling is coming soon on iPhone. No account; everything stays on your iPhone.
What is the upper limit of thiamin (B1)?
No tolerable upper intake level (UL) has been set for thiamin (B1), for adults or for any other life stage in the National Academies tables. The National Academies found too little data on adverse effects to set one.
Sources
- Food and Nutrition Board, National Academies of Sciences, Engineering, and Medicine. Dietary Reference Intakes (DRIs): Summary tables (Appendix J), in Dietary Reference Intakes for Sodium and Potassium (2019), Appendix J. NCBI Bookshelf NBK545442, tables J-2, J-3, J-8 and J-9. https://www.ncbi.nlm.nih.gov/books/NBK545442/
- NIH Office of Dietary Supplements, Thiamin (B1) fact sheet for health professionals.
- Ceiling reference data built 2026-10-03 from the tables above.
General information, not medical advice. Talk to a clinician about your own situation.