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| Benjamin U. Nwosu, MD |
A new study by pediatric endocrinologist Benjamin U. Nwosu, MD, finds that children in the United States exposed to second-hand smoke are far more likely to be low on vitamin D than their unexposed peers. The analysis of national data, published on Oct. 8 in PLOS One,found that vitamin D deficiency occurred in 21 percent of exposed children, compared to 15 percent of unexposed children and 18 percent of actively smoking youth. Tobacco smoke exposure independently predicted vitamin D deficiency after controlling for age, sex, race, body mass index, maternal education, and family socio-economic status.
“Our results show that second-hand smoke, which occurs indoors, is actually more deleterious with respect to vitamin D status than active smoking, which occurs outdoors in most cases,” said Dr. Nwosu, associate professor of pediatrics in the Division of Endocrinology/Diabetes. “We had expected the opposite.”
Essential for lifelong bone health, vitamin D is particularly crucial for growing children to achieve optimal bone mineralization needed to attain peak bone mass later in life. Vitamin D sufficiency is also crucial for the extra-skeletal functions in youth including the augmentation of both insulin sensitivity and immune system functions.
Nwosu and co-investigator Philip Kum-Nji, MD, MPH, associate professor of pediatrics at Virginia Commonwealth University School of Medicine, analyzed data from the National Health and Nutrition Examination Survey databank on 2,263 subjects of ages 3 to 17 years. Of these, 42 percent were exposed to second-hand smokeand 9 percent were active smokers. Non-exposure, second-hand smoke exposure and active smoking were quantified by the estimation of serum cotinine, a metabolite of nicotine which is the gold-standard marker for tobacco smoke exposure.
The central finding of this study adds to the growing list of negative health effects of tobacco smoke exposure in youth. It provides another reason for clinicians to recommend that adults not smoke indoors, Nwosu said.
“As pediatricians, we always ask if adults smoke in the house. Our study has added a missing environmental piece to causes of vitamin D deficiency in children and will help strengthen policies aimed at limiting or banning indoor smoking for the protection of young children,” he noted. “This report of an association between tobacco smoke exposure and lower vitamin D levels in children is another reason to be concerned about second-hand smoke. Adults can choose to smoke or not, but children can’t choose whether they’re exposed to second-hand smoke at home and elsewhere.”
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