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Vitamin B1 (thiamine)

Thiamin or thiamine is a generic term applied to all substances possessing vitamin B1 activity, regardless of the anion attached to the molecule. The cationic portion of the molecule is made up of a substituted pyrimidine ring connected by a methylene bridge to the nitrogen of a substituted thiazole ring. Vitamin B1 reportedly plays a role in the body's metabolic cycle for generating energy, aids in the digestion of carbohydrates and is important for the normal functioning of the nervous system, muscles and heart. It also stabilizes the appetite, promotes growth and good muscle tone. Thiamine is a water-soluble vitamin which functions as a coenzyme in a variety of enzyme systems especially those related to energy metabolism. Thiamine is stored in very small quantities (approximately 30 mg) with approximately half of the body stores being found in skeletal muscle with the remainder being found in the heart, kidney and nervous tissue including the brain. In a phosphorylated form, thiamine serves as the prosthetic group of enzyme systems that are concerned with the decarboxylation of alpha-ketoacids. Some decarboxylation reactions are reversible, so that synthesis may be achieved. Thus, thiamine is also important to the biosynthesis of keto-acids. Thiamin is involved in transketolase reactions. Thiamine is readily absorbed in aqueous solution from both the small and large intestine, and is then carried to the liver by the portal circulation. Thiamine, in its biologically active diphosphate form, acts as a coenzyme in two mitochondrial enzyme complexes--the pyruvate dehydrogenase (PDH) and the alpha-keto glutarate dehydrogenase (alpha-KGDH) complexes. Thiamine (vitamin B1) is an essential nutrient and an indispensable component in the oxidation of glucose, which is the main source of cellular energy in the central nervous system (CNS). In addition to its crucial role in cellular energy production, thiamine is an essential cofactor for activity of transketolase, an enzyme involved in biosynthetic reactions. Thiamine is required for normal conduction of electrical impulses along nerve fibers; and is implicated in the synthesis and neural release of acetylcholine, a neurochemical that plays an important role in learning and memory. Thiamin may enhance circulation, help with blood formation and the metabolism of carbohydrates. It is also needed for the health of the nervous system and is used in the biosynthesis of a number of cell constituents, including the neurotransmitter acetylcholine and gamma-aminobutyric acid (GABA). It is used in the manufacture of hydrochloric acid, and therefore plays a part in digestion. Deficiency in vitamin B1 may lead to the loss of appetite, weakness and feeling tired, paralysis and nervous irritability, insomnia, loss of weight, aches and pains, mental depression and constipation, heart and gastrointestinal problems.

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