Which vitamin serves as a coenzyme in energy metabolism and is essential to every body cell?

Which vitamin serves as a coenzyme in energy metabolism and is essential to every body cell?

• A. Niacin
• B. Thiamine
• C. Riboflavin
• D. Pantothenic acid

Answer: (A)

Vitamins that act as coenzymes are essential for turning nutrients into usable energy. Niacin provides the coenzymes NAD+ and NADP+, which shuttle electrons in many energy‑producing reactions. These cofactors participate in glycolysis, the conversion of pyruvate to acetyl‑CoA, the citric acid cycle, fatty acid oxidation, and oxidative phosphorylation, powering energy production in virtually every body cell. Without sufficient niacin, these pathways slow and energy output drops. While thiamine, riboflavin, and pantothenic acid are also needed for metabolism—through TPP in decarboxylations, FAD/FMN in redox steps, and CoA formation, respectively—the universal role of NAD+/NADP+ in energy metabolism makes niacin the best answer.

Vitamins that act as coenzymes are essential for turning nutrients into usable energy. Niacin provides the coenzymes NAD+ and NADP+, which shuttle electrons in many energy‑producing reactions. These cofactors participate in glycolysis, the conversion of pyruvate to acetyl‑CoA, the citric acid cycle, fatty acid oxidation, and oxidative phosphorylation, powering energy production in virtually every body cell. Without sufficient niacin, these pathways slow and energy output drops. While thiamine, riboflavin, and pantothenic acid are also needed for metabolism—through TPP in decarboxylations, FAD/FMN in redox steps, and CoA formation, respectively—the universal role of NAD+/NADP+ in energy metabolism makes niacin the best answer.