Micronutrient levels in children exposed to secondhand tobacco smoke

Antioxidant micronutrients are the body's primary defense against the oxidative stress of secondhand smoke (SHS). Micronutrient levels have been associated with lung function; decreased levels of vitamin C and β-carotene have been associated with SHS exposure in children. We sought to determine the association between SHS exposure and micronutrient levels in children.

Data from the 2003-2004 National Health and Nutrition Examination Survey (NHANES) were analyzed. Serum cotinine levels were categorized into no (<0.015 ng/mL), moderate (0.015 to <2.0 ng/mL), and high (2.0-15.0 ng/mL) smoke exposure; t-tests determined associations between exposure and levels of micronutrients. Significant bivariate associations were tested further using linear regression.

In all, 2,218 children, aged 6-18 years, were included (response rate of 82%); 17% had no, 76% moderate, and 7% high exposure. Children with no exposure had higher levels of vitamin A, C, and E, cis- and trans-β-carotene, and folate, while levels of vitamins B(6), B(12), and D did not differ. In regression analysis, higher cotinine levels were negatively associated with levels of vitamin C (β = -.03; p < .01), cis-β-carotene (β = -.04; p < .01), trans-β-carotene (β = -.7; p < .01), folate (β = -.5; p < .001) and vitamin A (β = -.6; p < .01).

Children exposed to SHS have lower levels of antioxidants controlling for dietary and supplement intake. This antioxidant depletion may increase systemic inflammation and sensitivity to other oxidant stresses. Parents should be counseled on these specific risks from SHS exposure for their children, and the importance of smoking cessation and eliminating children's exposure to tobacco smoke.