Thiamine deficiency in a chronic alcoholic can reduce energy production as a result of which of the following reasons?

Thiamine is a co-enzyme for pyruvate dehydrogenase and a-ketoglutarate dehydrogenase in the TCA pathway. Both the steps of the TCA cycle have thiamine requiring enzymes are required for the aerobic generation of ATP through krebs cycle. So thiamine deficiency can result in decreased energy production. Ref: Textbook of biochemistry by DM Vasudevan, 3rd Edition, Page 268