title: Effect of cigarette smoking on plasma homocysteine concentrations.
abstract: BACKGROUND
  Cigarette smoking has been recognized as a major risk factor for cardiovascular disease, while the role of homocysteine is still not clear. This study investigated the effects of smoking on plasma homocysteine concentration and determined the correlation between this parameter and biological markers of tobacco use, such as plasma thiocyanate and urine cotinine.
  
  
  METHODS
  Folate, vitamin B12 and homocysteine were measured in 300 subjects: 138 non-smokers and 162 smokers using immunoassay methods. Cotinine was measured using an enzymatic colorimetric method and thiocyanate by a selective electrode.
  
  
  RESULTS
  In smokers, we found a significant increase in homocysteine and a decrease in folate and vitamin B12 levels compared to non-smokers. Homocysteine was strongly correlated with the duration of use and the number of cigarettes consumed. Folate and vitamin B12 were significantly reduced in subjects smoking for more than 20 years compared to those who smoked less than 5 years. Among smokers, we noted a positive correlation between homocysteine and both plasma thiocyanates and cotininuria, and a negative-correlation between cotininuria and plasma folate.
  
  
  CONCLUSIONS
  Cigarette smoking increases homocysteine, which is strongly correlated with cotininuria and plasma thiocyanates. Moreover, smokers had tendency to develop hypofolatemia and hypovitamin B12, particularly when the duration of consumption exceeded 20 years.
authors.affiliation: Laboratory of Biochemistry-Toxicology, University Hospital of Monastir, Monastir, Tunisia. hajdhouha@yahoo.fr
authors.forename: Dhouha
authors.initials: D
authors.lastname: Haj Mouhamed
authors.forename: Asma
authors.initials: A
authors.lastname: Ezzaher
authors.forename: Fadoua
authors.initials: F
authors.lastname: Neffati
authors.forename: Wahiba
authors.initials: W
authors.lastname: Douki
authors.forename: Mohamed Fadhel
authors.initials: MF
authors.lastname: Najjar
mesh_terms: D000328:Adult; D003367:Cotinine / Q000652:urine; D005260:Female; D005492:Folic Acid / Q000097:blood; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D012907:Smoking / Q000097:blood*; D013861:Thiocyanates / Q000097:blood; D014805:Vitamin B 12 / Q000097:blood
chemical_list: D013861:Thiocyanates; D006710:Homocysteine; D005492:Folic Acid; D003367:Cotinine; C031760:thiocyanate; D014805:Vitamin B 12