Effects of Smoking on Metabolism and Excretion of Vitamin B12

Abstract

In view of evidence suggesting that there is a connexion between the metabolism of vitamin Bl2 and that of cyanide, and that smoking, which is associated with a high cyanide intake, may disturb the metabolism of B12; serum B21, urine B12 excretion, and urine thiocyanate excretion (an index of cyanide detoxication) have been measured in healthy smokers and non-smokers. The results show that urine B12 excretion is raised in smokers and that a high thiocyanate excretion is associated with an increase in B,2 excretion and a relatively low serum B12 concentration. The increase in B12excretion seems insufficient to account for the reduction in serum B12 concentration, which may be the result of disturbance of the equilibrium between serum and tissue B12 by high plasma cyanide concentrations. The work supports the idea that a high cyanide intake might produce derangements of B12 metabolism. © 1968, British Medical Journal Publishing Group. All rights reserved.