Thiamine deficiency decreases cellular metabolism because:
Thiamine is a coenzyme for pyruvate dehydrogenase and alfa-ketoglutarate dehydrogenases
Activity of transketolase is inhibited
It is required for the process of transamination
It is a cofactor in oxidative reduction
Thiamine deficiency results in decreased energy production because TPP interferes with its coenzyme for pyruvate and alphaketoglutarate dehydrogenase.Chronic peripheral Neuritis, Beriberi & Wemicke Encephalopathy with Korsakoff's Psychosis.Thiamin requirements increase in excess intake of carbohydrates and its deficiency leads to decreased energy production