Nutrient glossary
What is vitamin B1 (Thiamin)?
Thiamin turns carbohydrate into energy for nerves, brain and heart, arriving through wholegrains, pork, beans and fortified flour.
Reviewed 20 July 2026. General information, not medical advice.
The short version
Thiamin sits at the entry gate of carbohydrate metabolism: the more carbohydrate you burn, the more thiamin the reaction consumes. Nerves and the heart feel a shortfall first.
Wholegrains, pork, fish, beans and seeds carry it naturally, and UK white flour is fortified with it by law. Heavy alcohol intake is the classic route to deficiency because it blocks absorption.
Daily reference
1 mg a day
The reference is 1 mg a day for men and 0.8 mg for women.
This is the fixed adult reference used across these pages. In the app, your amount adjusts to your body and way of eating.
Best food sources of vitamin B1 (Thiamin)
Full ranking| Food | Per serving | Per 100g |
|---|---|---|
| Pork Tenderloin | 1.14 mg | 0.95 mg |
| Yeast Extract | 0.94 mg | 23.4 mg |
| Pizza (cheese) | 0.86 mg | 0.4 mg |
| Pork Chop | 0.74 mg | 0.57 mg |
| Bagel | 0.6 mg | 0.57 mg |
| Pasta (cooked) | 0.54 mg | 0.27 mg |
| Sausage (pork) | 0.44 mg | 0.4 mg |
| Sunflower Seeds | 0.41 mg | 1.48 mg |
Common questions
- Why is white bread a thiamin source?
- UK law requires white and brown flour to be fortified with thiamin, replacing what milling removes.
- Who runs short of thiamin?
- Mostly people with very high alcohol intakes or severely restricted diets; a normal mixed diet covers it.