Vitamin B3

Question 1

Vitamin B3 (niacin/nicotinic acid) is derived from ______________. [Hint: This is one of the 20 amino acids]

Answer 1

tryptophan (Trp)

Note that dietary intake of Trp is directly proportional to amount of niacin synthesised.

Question 2

State the role of niacin.

Answer 2

• The active forms of the vitamin; NAD+ (Nicotinamide Adenine Dinucleotide) and NADP+ (Nicotinamide Adenine Dinucleotide Phosphate) are required in oxidation-reduction reactions.
• Nicotinamide adenine dinucleotide (NAD+) is a major electron carrier in the oxidation of fuel molecules. The reactive part of NAD+ is its nicotinamide ring, a pyridine derivative synthesized from the vitamin niacin.

Question 3

State the outcome of vitamin B3 deficiency.

Answer 3

A dietary deficiency of tryptophan and niacin can lead to pellagra (Italian for “rough skin”), a disease characterized by dermatitis, diarrhea, and dementia.