That nicotinic acid (niacin) is important in the metabolism of human beings is an established fact supported by intensive experimental studies over many years. The amide of nicotinic acid, nicotinamide, has been shown to be an integral part of the pyridine nucleotide coenzymes that function in the oxidative enzyme systems which are necessary to the cell respiration of the living organism. There also is a possibility that nicotinic acid may have functions besides those involving oxidation systems, since it has been shown that a deficiency may affect the water and electrolyte balances,1 gastric motility2 and the metabolism of porphyrins3 and lipids.4 However, many experimental results from studies involving the biologic activity of nicotinic acid and its derivatives, especially nicotinamide, are contradictory. Hence, the theories based on them are difficult to coordinate and make any definite statements concerning the physiologic activities of nicotinic acid of doubtful value.
CORYELL MN, HARRIS ME, MILLER S, WILLIAMS HH, MACY IG. XXII. NICOTINIC ACID, PANTOTHENIC ACID AND BIOTIN CONTENTS OF COLOSTRUM AND MATURE HUMAN MILK. Am J Dis Child. 1945;70(3):150-161. doi:10.1001/archpedi.1945.02020210017004