Thiamine (vitamin B₁)

• The classical thiamine deficiency of humans is known as beriberi.  The milling/processing of 'refined' cereal grains (eg., polished rice and white flour) removes much of the naturally occurring thiamine (hence, requiring the addition of supplemental thiamine to avoid a deficiency of this vitamin).
• Thiamine acts as a coenzyme in the following types of biochemical reactions:
  • Oxidative decarboxylation of a-keto acids (eg., a-ketoglutarate, pyruvate, the a-keto analogs of the branched-chain amino acids: leucine, isoleucine and valine).
  • Transketolase reactions (eg., in the pentose phosphate pathway).