[Vitamin B1 (thiamine)].

Vitamin B1 (or thiamine) plays a key role in energy production from glucose. Since the main fuel of the nervous system is glucose, thiamine deficiency causes severe neurological symptoms. The biological exploration of vitamin B1 status is based on the measurement of thiamine pyrophosphate concentration or of the activity of a thiamine-dependent enzyme, transketolase, in erythrocytes. Severe deficiency states can be observed in chronic alcoholics, after protracted vomiting during pregnancy and after bariatric surgery. Mild deficiencies are common in the general population, but their clinical consequences are still unclear.