Lactic acidosis can be a result of deficiency of which vitamin?

• A. Folic acid
• B. Vitamin E
• C. Thiamin
• D. Vitamin C

Answer: (C)

Lactic acidosis arises when carbohydrate metabolism is hampered, especially at the step where pyruvate is converted to acetyl-CoA. Thiamin is a critical cofactor for the pyruvate dehydrogenase complex, so when thiamin is deficient, pyruvate can’t enter the TCA cycle efficiently. This causes pyruvate to be reduced to lactate instead, increasing lactate levels and lowering blood pH. Thiamin also supports other dehydrogenase reactions in energy metabolism, so its deficiency broadly impairs aerobic glucose utilization, prompting anaerobic glycolysis and lactic acidosis. In contrast, folic acid deficiency mainly affects DNA synthesis and red blood cell production, vitamin E deficiency leads to neurological and oxidative issues, and vitamin C deficiency causes scurvy; none of these directly disrupt pyruvate conversion to acetyl-CoA to cause lactic acidosis.