The primary symptoms beriberi (Vitamin B1 defeciency are neurological and cardiovascular disturbances such as myocardial damage, cardiac failure, and neuritis and neural paralyses accompanied by metabolic dysfunction in the form of lactate acidosis and branched-chain ketoaciduria. Further thiamine deficiency diseases are Wernicke's encephalopathy, Korsakov's syndrome, and several forms of Landry's paralysisVitamin B1 (thiamine) is a water-soluble vitamin and is synthesized by a variety of plants and microrganisms. It occurs in the free form, bound to protein or as the mono-, di-, or triphosphate ester. Since animals usually cannot synthesize it, humans must be supplied with exogenous vitamin B1 in the diet. Thiamine is absorbed from the small intestine both by passive diffusion and active transport. Subsequent part phosphorylation yields the physiologically most important coenzyme form, thiamine pyrophosphate (TPP). Thiamine is excreted via the kidney after dephosphorylation to the free form or as a conjugated sulphate ester. As TPP, thiamine is a coenzyme for the oxidative decarboxylation of 2-oxo acids and is thus involved in the organism's energy metabolism and main biosynthetic pathways. In addition, as a coenzyme for aldehyde- and ketotransferases, it is involved in the pentose phosphate pathway. In the nervous system it plays a role in the biosynthesis of lipids and acetylcholine.