Thiamine deficiency results in decrease energy production, because TPP:
Link reaction & TCA cycle requires 5 coenzymes: Lipoic acid and four B-complex Vitamins (B1, B2, B3, B5). Due to this reason, Thiamine (vitamin B1) deficiency results in decrease energy production (also CNS problems because Brain cells depend on this aerobic reaction) as TCA & link reaction both are responsible for energy production in cells.
Interferes with Alcohol metabolism
Interferes with Transketolase activity
Is cofactor for pyruvate dehydrogenase and alpha ketoglutarate dehydrogenase
Interferes with Energy production from amino acids
Link reaction