Relationship between smoking, dietary intakes and plasma levels of vitamin E and β-carotene in matched maternal-cord pairs

The concentrations of tocopherols and carotenoids are lowered in umbilical cord blood plasma, which may have a negative effect on antioxidant protection in neonates. Smoking may adversely affect dietary intakes and plasma concentrations of carotenoids. The dietary intakes of vitamin E and β-carotene were assessed in 66 pregnant women (31 smokers and 35 non-smokers) between 10 and 20 weeks gestation using a food frequency questionnaire. The concentrations of α-tocopherol and β-carotene were measured in maternal plasma at the time of the dietary assessment, and in the matched umbilical cords of their newborn after delivery. In smoking and non-smoking mothers, the mean intakes of vitamin E (9.3 [SD 5] and 8.2 [SD 5] mgd^-1) and β-carotene (3464 [SD 1885] and 2977 [SD 1503] μgd^-1) were not significantly different. The plasma concentrations of α-tocopherol (20.8 [SD 4] and 20.5 [SD 4] μmolL^-1), the α-tocopherol to lipid ratios (3.2 [SD 0.8] and 3.5 [SD 0.8]) and the plasma concentrations of β-carotene (0.22 [SD 0.1] and 0.22 [SD 0.1] μmolL^-1) were not significantly different in smoking and non-smoking mothers. There were no significant differences in plasma α-tocopherol (7.4 [SD 2] and 7.3 [SD 2] μmolL^-1), in α-tocopherol to lipid ratios (3.2 [SD 0.6] and 2.8 [SD 0.6]) or in β-carotene concentrations (0.05 [SD 0.04] and 0.03 [SD 0.02] μmolL^-1) in cords from newborns of smoking and non-smoking mothers. There was a significant correlation (r = 0.41, P = 0.015) between dietary intakes and plasma concentrations of β-carotene in non-smoking mothers. However, this relationship was not significant in smoking mothers (r = 0.28, P = 0.12). There were no relationships between dietary intakes and plasma concentrations of tocopherol. These results indicate that smoking during pregnancy does not appear to affect the dietary intakes or plasma concentrations of α-tocopherol and β-carotene in pregnant women or their babies. However, smoking does influence the relationship between dietary intakes and plasma levels of β-carotene.