More commonly called "Vitamin B1." Thiamine serves as a coenzyme for the decarboxlyation of pyruvate and oxidation of alpha keto-glutamic acid. Thiamine is found in yeast, beans, peas, nuts, pork and beef.

Deficiency of this vitamin causes beriberi. In chronic alcoholics in the developed world, who are commonly thiamine deficient, Wernicke-Korsakoff syndrome is a more common presentation than classical beriberi.