Thiamine, commonly known as vitamin B1, is a water-soluble nutrient that belongs to the B complex of vitamins. Its basic chemical forms are the free vitamin and phosphorylated derivatives that participate in enzymatic reactions. Thiamine is frequently discussed in nutrition and medicine for its role in energy metabolism and nervous system maintenance. See general nutrient information on water-soluble vitamins.

Biological role and active forms

Inside cells thiamine is converted to phosphorylated forms, most notably thiamine pyrophosphate (TPP), which serves as a coenzyme in several key biochemical pathways. TPP and related phosphate derivatives assist enzymes that catalyze steps in carbohydrate and amino‑acid catabolism and in the synthesis of some neurotransmitters. For details on phosphorylated forms, consult phosphate derivatives and for pathways where thiamine acts as a cofactor see catabolism and metabolic enzymes.

Dietary sources and supplements

Thiamine is found naturally in a variety of foods and is also available in manufactured supplements and fortified products. Rich dietary sources include whole grains, legumes, nuts, seeds and some meats; legumes are often highlighted as a good plant source (legumes). Commercially available preparations and fortified foods are common ways to maintain intake: see references for supplements (dietary supplements).

Deficiency, clinical uses and at‑risk groups

A lack of thiamine leads to disorders of energy metabolism that most classically present as beriberi, which affects the cardiovascular and nervous systems. Acute deficiency can also contribute to Wernicke–Korsakoff syndrome in people with chronic alcohol use. Clinical thiamine preparations are used in treatment and prevention of deficiency-related conditions; medication and therapeutic formulations are described in medical references (medications).

History and public health

Recognition of thiamine’s importance emerged from investigations of deficiency conditions in the late 19th and early 20th centuries. Public‑health measures such as food fortification and dietary guidance have reduced overt deficiency in many populations, though it remains a concern where diets rely heavily on polished rice or lack diversity. Classic accounts of deficiency are available under historical disease descriptions like beriberi.

Practical notes

  • Cooking and processing can reduce thiamine content in some foods.
  • Populations with limited diets, certain medical conditions, or high alcohol intake are at greater risk.
  • Supplements and fortified foods offer reliable preventive options; consult healthcare guidance for therapeutic use (supplements, medications).