Thiamine Monograph

Biochemistry and Pharmacokinetics Thiamine functions as a coenzyme in more than 24 enzymes, most importantly pyruvate dehydrogenase (for energy production in the Krebs cycle), transketolase (for lipid and glucose metabolism, production of branched chain amino acids, and production and maintenance of myelin sheath), and 2-oxo-glucarate dehydrogenase (for synthesis of acetylcholine, GABA, and glutamate). Thiamine is necessary in the functioning of the hexose monophosphate shunt, an anabolic pathway used proportionately more in adrenal cortex, leukocytes, erythrocytes, and mammary gland tissue. Thiamine is crucial in glucose energy-utilizing pathways, particularly in the central nervous system, which needs a continuous supply of glucose. Thiamine has also been shown to mimic acetylcholine in the brain, which may explain its possible action in Alzheimer’s disease and other dementias. The body stores approximately 25-30 mg of thiamine, mainly in skeletal muscle, heart, brain, liver, and kidneys – organs with high metabolic need. In a deficient state, body stores can be depleted in 2-3 weeks. As early as one week after thiamine stores are depleted the blood-brain barrier is disrupted and local cerebral hypoperfusion results, leading to the classic signs of Wernicke’s encephalopathy.