Which of the following B vitamins acts as a coenzyme in the decarboxylation of alpha-keto acids in the citric acid cycle?

A Thiamine (Vitamin B1) ✓
B Riboflavin (Vitamin B2)
C Niacin (Vitamin B3)
D Pantothenic acid (Vitamin B5)

Explanation

Thiamine, in its diphosphate form (TPP), serves as a coenzyme for the decarboxylation of alpha-keto acids to aldehydes, which is essential in the citric acid cycle and the pentose phosphate pathway.

Mnemonic

'Thiamine' sounds like 'theme', implying it's central to metabolic themes

Source

Biochemistry textbooks and scientific literature
Vitamins Biochemistry Coenzymes in metabolic pathways Hard MEDICAL Confidence: high