Thiamin (Vitamin B1)
Thiamin (or thiamine) is one of the water-soluble B vitamins. Thiamin is naturally present in some foods, added to some food products, and available as a dietary supplement. This vitamin plays a critical role in energy metabolism and, therefore, in the growth, development, and function of cells. The vitamin has a short half-life, so people require a continuous supply of it from the diet. In highly industrialized countries, chronic alcohol use disorders appear to be the most common cause of thiamin deficiency. Up to 20%–30% of older adults have laboratory indicators that suggest some degree of thiamin deficiency. Administration of supplemental thiamin, often parenterally, quickly cures beriberi. In rare cases, beriberi causes congestive heart failure that leads to edema in the lower limbs and, occasionally, death.
Where to get it
We earn a commission if you buy through these links. It doesn't change your price. How we make money
Active compounds & mechanisms
Key compounds:
Research & evidence
Strong support Some support Weak or no supportColours show how well the sources back each point. The reason is next to each one.
According to animal model studies, thiamin deficiency might play a role in the development of Alzheimer’s disease. NIH ODS says larger, well-designed studies are needed to determine whether thiamin supplements are beneficial for Alzheimer’s disease.
Preclinical onlyWeak or no support. Mostly lab or animal studies
Study details
NIH ODS: “According to animal model studies, thiamin deficiency might play a role in the development of Alzheimer’s disease.” NIH ODS: “Larger, well-designed studies are needed to determine whether thiamin supplements are beneficial for Alzheimer’s disease.”
Source: NIH ODS, Thiamin — Health Professional Fact Sheet (Updated February 9, 2023), Thiamin and Health View source
Dosage
| Form | Amount |
|---|---|
| Any form | No standard dose is listed by our sources. |
Side effects
Well documented Reported (case reports, anecdotal or one study) None reportedThe circle shows how well documented an effect is, not how serious it is. A rarely reported effect can still be serious, so always read ‘When to stop’.
| Effect | Frequency | When to stop |
|---|---|---|
| Thiamin is generally considered safe with no established tolerable upper intake levelNone reportedNo side effects reported by our sources | Adverse effects are very rare even at high doses | Stop and talk to a doctor if you notice any unexpected or concerning symptoms. |
Safety & interactions
Safety
The body excretes excess amounts of thiamin in the urine. Because of the lack of reports of adverse effects from high thiamin intakes (50 mg/day or more) from food or supplements, the FNB did not establish ULs for thiamin. It has been hypothesized that the apparent lack of toxicity may be explained by the rapid decline in absorption of thiamin at intakes above 5 mg. However, the FNB noted that in spite of the lack of reported adverse events, excessive intakes of thiamin could have adverse effects.
Contraindications
Drug interactions
NIH ODS thiamin fact sheet lists no drug interactions. Talk with your healthcare provider before taking thiamin supplements if you take any medication.
Related
Was this page useful? Rate it · Report a mistake