Vitamin B3 (niacin)

A B vitamin central to energy metabolism, which the body can also make in small amounts from the amino acid tryptophan.

Frank deficiency is rare where diets are varied, so this is usually measured as part of a broad vitamin screen rather than on suspicion.

Because the body makes some of its own, the blood level reflects protein intake as well as niacin intake. Assays vary between laboratories, so compare only values from the same provider.

Worth reading as part of a full vitamin panel rather than alone.