LOCAL AND SYSTEMIC EFFECTS OF CIGARETTE-SMOKING ON FOLATE AND VITAMIN-B-12

A cross-sectional study was carried out among 39 current smokers (CS) and 60 noncurrent smokers (NCS) to evaluate the effects of cigarette s moking on folate and vitamin B-12 concentrations in the circulation an d in tissues directly ex posed to cigarette smoke. Univariate analysis showed significantly lower plasma, red blood cell (RBC), and buccal m ucosa (BM) folate and BM vitamin B-12 concentrations in CS compared wi th NCS. The association between smoking and folate and vitamin B-12 co ncentrations in plasma, RBCs, and BM cells was reduced after other var iables were controlled for. Total folate intake and plasma vitamin C c oncentrations were significant predictors of plasma and RBC folate con centrations. The plasma and RBC concentrations of folate were signific antly lower in subjects who had last smoked < 1 h before the blood sam ple was drawn than in subjects who had smoked earlier. At the current recommended dietary allowance (RDA) for folate, CS had 42% lower plasm a folate concentrations than NCS, whereas at an intake three times the RDA, the plasma folate concentration was the same for CS and NCS. The results also suggested that CS have BM folate and vitamin B-12 concen trations that are lower than those of NCS.