Effect of Niacin Precursors on the Excretion of Niacin Metabolites.

Abstract
Tests indicate that isocinchomeronic acid is not an intermediate in the synthesis of niacin. Ornithine and anthranilic acid seem to stimulate its synthesis in the intestinal tract only. The data neither prove nor refute the theory that quinolinic acid is a possible intermediate in the tryptophan niacin synthesis scheme.