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Alterations in biochemical pathways induced by nitrous oxide

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Nitrous oxide inactivates vitamin B12 by oxidation of the cobalt atom, leading to functional defects in vitamin B12 as a cofactor for the catabolism of homocysteine and methylmalonic acid. Thus, the circulating concentrations of methylmalonic acid and homocysteine are increased in N2O-induced vitamin B12 deficiency.

Abbreviations: AdB12, adenosyl-vitamin B12; CBS, cystathionine beta-synthase; MeB12, methyl-vitamin B12; MMCoAM, methylmalonyl- CoA mutase; MTR, methionine synthase; N2O, nitrous oxide; THF, 5-methyl tetrahydrofolate.

(Source: Leleu D, Denimal D. A case of functional vitamin B12 deficiency after recreational nitrous oxide use. Biochem Med [Zagreb] 2024;34[1]:010801. Creative Commons Attribution 4.0 International [CC BY 4.0] license, creativecommons.org/licenses/by/4.0.)