Overview

Vitamin B1, or thiamine, is a water-soluble vitamin required for energy metabolism, nerve function, and cellular biosynthetic pathways. The active coenzyme form is thiamine diphosphate. Severe deficiency can cause beriberi or Wernicke–Korsakoff syndrome. See also Vitamin B1 and B-complex vitamins.

Mechanism

Thiamine diphosphate supports pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, branched-chain alpha-ketoacid dehydrogenase, and transketolase. These enzymes connect carbohydrate and amino-acid metabolism with ATP production and nucleotide synthesis.

Uses

Clinicians use thiamine to prevent or treat deficiency, including deficiency associated with alcohol-use disorder, malnutrition, malabsorption, prolonged vomiting, or bariatric surgery. Treatment route and urgency depend on symptoms and clinical risk.

Dosage

Reference intake for adults is commonly about 1.1 mg/day for women and 1.2 mg/day for men, with higher needs during pregnancy and lactation. Deficiency treatment may require substantially higher oral or parenteral doses prescribed by a clinician. Do not self-treat suspected neurologic deficiency.

Adverse effects

Oral thiamine is generally well tolerated. Rare hypersensitivity reactions, especially after parenteral administration, can be serious. Seek urgent care for breathing difficulty, facial swelling, or widespread rash.

Claims and evidence

Thiamine is essential when deficient, but supplementation above nutritional requirements has not been established as a universal energy or cognitive enhancer in replete people. Evidence is condition-specific and product quality varies.

Research

Current research examines thiamine status in critical illness, diabetes, heart failure, neurodegenerative disease, and genetic disorders of thiamine transport or metabolism. Results should be interpreted alongside clinical trials and biomarker limitations.