Effect of Smoking on Serum Concentrations of Total Homocysteine, Folate, Vitamin B₁₂, and Nitric Oxide in Pregnancy: A Preliminary Study

Abstract

Objective: Nitric oxide (NO) is a potent vasodilator released by endothelial cells that plays an important role in modulating maternal and fetal vascular tone in normal pregnancy. Lower plasma levels of vitamins may result in hyperhomocysteinemia, a known risk factor in pregnancy. The aim of this study was to investigate whether there are alterations in the serum levels of total homocysteine (tHcy), folate, vitamin B₁₂, and total nitrite, as an index of NO, in smoking as compared with age-matched nonsmoking pregnant women. Methods: Thirty-three women (19 smoking and 14 nonsmoking) between 16 and 22 weeks of their gestation were included in this study. The serum tHcy levels were analyzed by using an enzyme-linked immunosorbent assay kit. Vitamin B₁₂ and folate values were measured by means of DPC kits. Total nitrite was measured by Griess reaction as an index of endogenous NO production. Results: The serum tHcy concentrations were significantly increased in smoking as compared with nonsmoking pregnant women (p < 0.001). The folate and vitamin B₁₂ concentrations were lower in smoking than in nonsmoking pregnant women, but only the differences in folate concentrations were statistically significant (p < 0.001). The tHcy concentrations showed a significant negative correlation with folate in the smoking pregnant women. The serum total nitrite concentrations were lower in smoking than in nonsmoking pregnant women (p < 0.05). In addition, the serum nitrite levels in smoking pregnant women had significant negative correlations with tHcy and positive correlations with folate and vitamin B₁₂ levels. Conclusions: In the light of our findings, we propose that smoking might enhance the vasoconstrictor capacity in pregnant women by increased tHcy concentrations and by a simultaneous decrease in the production of NO which is a vasodilator compound.

Folate pathway and nonsyndromic cleft lip and palate

“…Moreover, it provides support for studies suggesting that hyperhomocysteinemia may play an etiologic role (Knott et al, 2003; Ozerol et al, 2004; Rubini et al, 2005b; Verkleij-Hagoort et al, 2007; Wong et al, 1999). Notably, we interrogated only a subset of the genes in the folate and related pathways and there are other genes in this complex set of pathways that were not addressed in this study.…”

“…Smoking has been implicated as a risk factor and been shown to lower the levels of folic acid and increase homocysteine (Jauniaux et al, 2007; Ozerol et al, 2004). Elevated levels of homocysteine and its conversion to homocysteine-thiolactone have been suspected of contributing to the post-translational modification of the folate receptors (Jakubowski et al, 2009).…”

Relationship between the plasma total homocysteine levels and skipping breakfast during pregnancy

“…In addition, several studies have shown that other lifestyle factors such as smoking, caffeine intake and physical activity might also affect the circulating total homocysteine (tHcy) levels (Refsum, Nurk, Smith, et al, 2006;Ozerol, E., Ozerol, I., Gökdeniz, et al, 2004;Vollset, Refsum, Irgens, et al, 2000).…”

The effect of cigarette smoke exposure on developing folate binding protein-2 null mice

“…Women who smoke cigarettes during pregnancy have been shown to have lower serum folate levels than pregnant women who do not smoke cigarettes (32–34). Thus, it is reasonable to postulate that folate deficiency may be related to the risk of smoking-related adverse effects on the developing embryo/fetus.…”

“…An association exists between maternal smoking and decreased folate levels (32–34) and may underlie the increased risk of smoking-induced low birth weight. Compounding this risk is the fact that poor nutrition and decreases in dietary intake of folate-rich fruits and vegetables are common in smokers, or spouses of smokers (35).…”