Influence of environmental tobacco smoke on vitamin C status in children.

BACKGROUND It is known that vitamin C status is compromised in smokers. The vitamin C status of nonsmokers who are exposed to environmental tobacco smoke (ETS) is now being elucidated. OBJECTIVE We assessed vitamin C status in children who were either exposed or not exposed to ETS, and we sought to associate changes in vitamin C status with the amount of ETS exposure. DESIGN The study group included 512 children aged 2-12 y; 50% of them were exposed to ETS in the home because their parents smoked. Dietary intake of vitamin C, obtained with a 24-h recall questionnaire, and blood ascorbate concentrations were compared in the exposed and unexposed groups. Smoke exposure was assessed by measuring a biomarker, urinary cotinine. Age, sex, and body mass index were examined as potential correlates of vitamin C status in each exposure category. RESULTS Plasma ascorbate concentrations were lower, by 3.2 micro mol/L on average, in ETS-exposed children than in unexposed children who consumed equivalent amounts of vitamin C; this was a highly significant difference (P = 0.002). This reduction in plasma ascorbate occurred even with very low exposure to ETS. CONCLUSIONS ETS can reduce concentrations of ascorbate, an important blood antioxidant, even when the amount of smoke exposure is minimal. Children exposed to ETS should be encouraged to consume increased amounts of foods rich in vitamin C or should be given the equivalent amount of this vitamin as a supplement.