Cobalamin

Vitamin B12/Nutrient Depletion:

  • AlcoholAlcohol: According to secondary sources, excessive alcohol intake lasting longer than two weeks may decrease vitamin B12 absorption from the gastrointestinal tract.
  • Angiotensin-converting enzyme inhibitors (ACEIs)Angiotensin-converting enzyme inhibitors (ACEIs): In clinical research, therapy with ACE inhibitors was associated with a decline in serum vitamin B12 levels (64).
  • AntibioticsAntibiotics: According to anecdotal reports, long-term antibiotic use may deplete vitamin B12 levels.
  • AnticonvulsantsAnticonvulsants: Anticonvulsants such as carbamazepine, oxcarbazepine, and valproic acid have been associated with reduced vitamin B12 absorption, and reduced serum and cerebrospinal fluid levels in some patients (66; 67).
  • AspirinAspirin: In human research, there was a higher prevalence of vitamin B12 deficiency in patients using acetylsalicylic acid (aspirin) compared to nonusers (65).
  • Bile acid sequestrantsBile acid sequestrants: In vitro, colestipol (Colestid?) and cholestyramine (Questran?) resins were highly bound to vitamin B12-intrinsic factor complex (68). Secondary sources suggest that bile acid resins may reduce vitamin B12 absorption.
  • ChloramphenicolChloramphenicol: In vitro, chloramphenicol has been found to inhibit the biosynthesis of vitamin B12 (87).
  • ColchicineColchicine: According to animal research, colchicine may induce the malabsorption of several nutrients, including vitamin B12 (69).
  • H2 blockersH2 blockers: According to human research, prolonged reduction in the secretion of gastric acid and pepsin caused by long-term use of H2 blockers may reduce absorption of vitamin B12 (70; 71).
  • MetforminMetformin: In patients with type 2 diabetes, metformin use has been shown to reduce serum folic acid and vitamin B12 levels (72; 73; 74; 64).
  • NeomycinNeomycin: According to a review, absorption of vitamin B12 may be reduced by neomycin (75).
  • NicotineNicotine: According to secondary sources, nicotine may reduce serum vitamin B12 levels. The need for vitamin B12 supplementation has not been adequately studied (83; 84).
  • Nitrous oxideNitrous oxide: A case report of symptomatic vitamin B12 deficiency after nitrous oxide administration in a patient with subclinical B12 deficiency was reported (76).
  • Oral contraceptivesOral contraceptives: The data regarding the effects of oral contraceptives on vitamin B12 serum levels are conflicting. Some studies have found reduced serum levels in birth control pill users, but others have found no effect despite the use of birth control pills for up to six months (77; 78; 79).
  • PotassiumPotassium: Potassium supplements may reduce absorption of vitamin B12 in some people. This effect has been reported with potassium chloride (81; 82). According to case report data, correction of megaloblastic anemia with vitamin B12 may result in fatal hypokalemia in susceptible individuals (62).
  • Proton pump inhibitors (PPIs)Proton pump inhibitors (PPIs): According to human research, prolonged reduction in the secretion of gastric acid and pepsin caused by long-term use of PPIs may reduce absorption of vitamin B12 (70; 71). In people receiving long-term PPI therapy, oral vitamin B12 supplementation at RDA doses may not help prevent deficiency (131). Treatment with cyanocobalamin nasal spray may help improve vitamin B12 status (104).
  • SalicylatesSalicylates: In preliminary research, para-aminosalicylic acid has been shown to inhibit vitamin B12 absorption (80; 81).
  • Vitamin CVitamin C: Preliminary evidence suggests that vitamin C may cause the degradation of vitamin B12 in multivitamin supplements (86).
  • ZidovudineZidovudine: Reduced serum vitamin B12 levels may occur when zidovudine (AZT, Combivir?, Retrovir?) therapy is started. However, available data suggest that vitamin B12 supplements are not helpful for people taking zidovudine (85).