Vitamins

Vitamin B1 (Thiamine)

Also known as: Thiamine, Thiamin, Benfotiamine, Vitamin B1 supplement

The energy-metabolism vitamin — essential for turning food into fuel, with a deficiency story that shaped food policy.

By IngredientWiki Editorial Team
Fact-checked by IngredientWiki Editorial Team
Updated 2026-09-26
2 min read

In short

Thiamine — vitamin B1 — was the first vitamin ever discovered, and its job is fundamental: it is a required cofactor for enzymes that convert carbohydrates into energy, with brain and heart tissue especially dependent on the supply. Deficiency, historically beriberi and Wernicke-Korsakoff syndrome in heavy alcohol use, is now mostly confined to those specific populations — alcohol use disorder, malabsorption, certain bariatric surgeries. For most people, food covers it. The supplement market adds one interesting modern chapter: benfotiamine, a fat-soluble synthetic form, studied for diabetic complications with modest supporting evidence.

First vitamin discovered (1910s) — essential coenzyme for energy
Brain and heart are the most thiamine-hungry tissues
Deficiency: beriberi and Wernicke-Korsakoff (alcohol-related)
Benfotiamine form studied for diabetic neuropathy

What is Vitamin B1 (Thiamine)?

Thiamine holds a permanent place in nutrition history as the molecule that started the vitamin era — the first deficiency disease traced to a specific dietary compound. The biochemistry that earned it the discovery remains its identity: thiamine pyrophosphate, its active form, sits at the heart of carbohydrate metabolism, and tissues that run constantly on glucose — brain, heart, nerves — are the first to fail without it. For the average eater, thiamine is a solved problem; for specific populations and for the synthetic derivative benfotiamine, it remains a live clinical topic.

Where it comes from

Natural sources

Found in whole grains, pork, legumes, seeds, and fortified cereals
White rice polishing removed the thiamine-rich bran — the original beriberi story
Heat- and water-sensitive; boiling and soaking reduce content

How it's made

Supplements use thiamine HCl or mononitrate; benfotiamine is a fat-soluble synthetic derivative with different tissue distribution.

What it does in products

Benefits

Essential energy metabolism

strong evidence

Thiamine is required to turn carbohydrate into usable energy — a foundational role, though supplementation in replete people adds nothing.

Deficiency treatment

strong evidence

High-dose thiamine reverses beriberi and is standard care in Wernicke-Korsakoff syndrome — deficiency contexts where it is life-saving.

Diabetic neuropathy (benfotiamine)

moderate evidence

Trials of benfotiamine show modest reductions in neuropathic symptoms and markers; promising but not yet standard care.

Side effects & safety

Stomach upset (uncommon)Uncommon at typical doses; take with food.

Allergic reaction (injected thiamine) (rare)Rare, mostly with parenteral use.

Safety considerations

Thiamine is safe and required in pregnancy — prenatal vitamins include it; high-dose use in hyperemesis is medically supervised.
None significant at supplement doses.
Not for: None of note

How it's used

In supplements

RDA: 1.2 mg/day (men), 1.1 mg/day (women). Most supplements provide 50–100 mg — far above need but harmless, as excess is excreted. Benfotiamine trials used 300–600 mg daily for neuropathy.

Regulatory status

Dietary supplement under DSHEA and GRAS nutrient for fortification; prescription thiamine exists for deficiency treatment.
GRAS (generally recognized as safe) for food use.

Who actually needs thiamine supplements?

For a vitamin this essential, the supplement market is oddly narrow — because food supplies it and the body stores only weeks' worth. The clinical populations that genuinely need thiamine are specific and well-defined: people with alcohol use disorder (alcohol blocks absorption and activation, and deficiency can cause irreversible brain damage), those with severe malabsorption or bariatric surgery, prolonged vomiting in pregnancy (hyperemesis), and some heart-failure patients on loop diuretics. Outside these groups, a thiamine supplement is mostly insurance without a claim. The benfotiamine chapter is separate — a research-interest derivative, not a deficiency correction.

Frequently asked questions

What are the symptoms of thiamine deficiency?

Early: fatigue, irritability, poor memory, and nerve tingling. Advanced: beriberi (heart failure, edema, neuropathy) and Wernicke-Korsakoff syndrome (confusion, eye-movement problems, memory loss). The latter is a medical emergency.

Does vitamin B1 give you energy?

It enables energy production — but only if you were deficient. In replete people, extra thiamine produces no energy boost, despite the 'B vitamins for energy' marketing.

What is benfotiamine?

A fat-soluble synthetic thiamine derivative that reaches tissues more effectively than standard thiamine. It is studied for diabetic neuropathy and kidney protection, with modest positive trial data — a distinct product from regular B1.

The bottom line

Thiamine is an essential, well-understood vitamin whose supplementation is rarely needed outside specific medical contexts — but in those contexts it is life-saving. The benfotiamine derivative is a separate, promising research story for diabetic complications.

References

Thiamin fact sheet for health professionals. NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional/
Thiamine deficiency and Wernicke encephalopathy — literature search. PubMed (National Library of Medicine). https://pubmed.ncbi.nlm.nih.gov/?term=thiamine+Wernicke+encephalopathy
Benfotiamine and diabetic neuropathy — literature search. PubMed (National Library of Medicine). https://pubmed.ncbi.nlm.nih.gov/?term=benfotiamine+diabetic+neuropathy+randomized
Thiamine compound summary. PubChem (National Library of Medicine). https://pubchem.ncbi.nlm.nih.gov/compound/1130