Vitamin B3

Niacin and Niacinamide/Nutrient Depletion:

  • 5-Fluorouracil5-Fluorouracil: According to human case reports and secondary sources, 5-fluorouracil may cause niacin deficiency (482; 483; 484).
  • AzathioprineAzathioprine: According to human case report and secondary sources, azathioprine may cause niacin deficiency (485).
  • ChloramphenicolChloramphenicol: According to secondary sources, chloramphenicol may cause niacin deficiency (482).
  • CycloserineCycloserine: According to human case report, cycloserine may cause niacin deficiency (486).
  • Decarboxylase inhibitors (e.g., benserazide, carbidopa)Decarboxylase inhibitors (e.g., benserazide, carbidopa): According to human case reports, decarboxylase inhibitors may cause niacin deficiency (487). These agents inhibit the enzyme involved in the conversion of tryptophan to niacin (487).
  • EthionamideEthionamide: According to human case report, chloramphenicol may cause niacin deficiency (486).
  • IsoniazidIsoniazid: Isoniazid may cause a deficiency of pyridoxine, which is necessary for the conversion of tryptophan to niacin, thus inducing pellagra or niacin deficiency in poorly nourished patients (488; 489; 432; 454).
  • MercaptopurineMercaptopurine: According to human case report and secondary sources, 6-mercaptopurine may cause niacin deficiency, likely due to 6-mercaptopurine interfering with the synthesis of adenine dinucleotide (485).
  • Minerals (zinc sulfate)Minerals (zinc sulfate): Oral administration of zinc sulfate to alcoholics with pellagra has been shown to increase the urinary excretion of niacin metabolites, suggesting its ability to affect the metabolism of tryptophan to niacin, and having possible implications for the concurrent administration of zinc and niacin (468).
  • Pantothenic acidPantothenic acid: The results of one crossover study in adolescents found that supplementation with pantothenic acid increased urinary secretion of niacin; this may have implications for the concomitant use of the two B-complex vitamins (469).
  • PhenobarbitalPhenobarbital: According to secondary sources, phenobarbital may cause niacin deficiency (483).
  • PhenytoinPhenytoin: According to human case reports and secondary sources, phenytoin may cause niacin deficiency (490; 483).
  • PyrazinamidePyrazinamide: According to human research, pellagra may occur with concomitant use of pyrazinamide and niacin due to structural similarities between pyrazinamide and nicotinamide (454). The administration of a diet rich in pyrazinamide has been shown to significantly increase the metabolism of tryptophan to niacin in rats (455), which may have implications for the concurrent use of niacin and pyrazinamide in humans.
  • Valproic acidValproic acid: According to human case reports and secondary sources, valproic acid may cause niacin deficiency (490; 483).