Vitamin B1 (Thiamine)
The energy vitamin. Without it, carbohydrates can't be turned into fuel.
Vitamin B1 (thiamine) is required to convert carbohydrates into usable energy and to keep nerve cells signalling properly. It is water-soluble, so the body holds only a small reserve and needs a steady daily supply rather than occasional large doses. Standard thiamine HCl is well absorbed at normal intakes, but absorption flattens off at high doses because gut transport is limited. Benfotiamine, a fat-soluble form, gets round that ceiling and reaches higher blood levels, which is why it shows up in nerve-support formulas aimed at higher doses than food alone provides.
Reference values
Daily reference values from official nutrition authorities. These are population reference figures, not personal recommendations.
| RDA | Upper limit | Source |
|---|---|---|
| 1.1 mg | No UL set | UK SACN DRVs (1991) — thiamine RNI is energy-dependent (~0.4mg/1000kcal); 1.1mg/day used as general adult reference. No SACN or EFSA numerical UL established. |
| 1.1 mg | No UL set | UK SACN DRVs (1991) — thiamine RNI is energy-dependent (~0.4mg/1000kcal); 1.1mg/day used as general adult reference. No SACN or EFSA numerical UL established. |
Forms and bioavailability
Not all forms are absorbed equally. The form on your supplement label affects how much your body can actually use.
| Form | Absorption | With food | Timing | Evidence |
|---|---|---|---|---|
| Thiamine HCl | Typical | With food | Morning | Strong |
| Benfotiamine (fat-soluble thiamine) | Higher | With food | Morning | Likely |
Stack Almanac tracks your thiamine form and totals it across every source, including any B-complex or multivitamin, so a benfotiamine supplement and a plain B1 tablet don't quietly double up without you noticing.
Track your Vitamin B1 (Thiamine) in Stack Almanac
Last reviewed: 2026-07-08. Reference values are adult-general RDAs from UK. Individual needs may vary. This page is for informational purposes only and is not a substitute for professional medical advice.