A deficiency in which vitamin would impair the activity of the pyruvate dehydrogenase complex?

• A. Thiamine (Vitamin B1)
• B. Vitamin C
• C. Vitamin A
• D. Vitamin D

Answer: (A)

The pyruvate dehydrogenase complex relies on thiamine in the form of thiamine pyrophosphate as a crucial cofactor to decarboxylate pyruvate and convert it into acetyl-CoA for entry into the TCA cycle. When thiamine is deficient, PDH activity drops, causing pyruvate to build up and be diverted to lactate, compromising aerobic glucose oxidation and energy production. This makes a deficiency of thiamine the vitamin that would impair PDH function. Vitamins C, A, and D do not serve as cofactors for PDH, so they don’t affect this enzyme complex in the same way.