Dietary intake, physical activity, body mass index, and childhood asthma in the Third National Health And Nutrition Survey (NHANES III).

Childhood asthma may be affected by dietary changes and increased body mass related to a sedentary lifestyle, although the mechanisms are poorly understood. To test this hypothesis, we used data from the National Health and Nutrition Survey (NHANES III) from 1988-1994, including 7,904 children. We analyzed cross-sectional information on body mass index (BMI = weight/height2), physical activity (hr/day viewing television), dietary intake (24-hr recall), and vitamin C intake (60 mg/day). The probability of self-reported asthma or wheezing relating to risk factors was calculated by logistic regression. After controlling for dietary intake, physical activity, and sociodemographic variables, asthma risk was three times higher for children aged 6-16 years in the highest percentiles of BMI (>95th percentile) when compared to children in percentiles 25-49 (OR = 3.44; 95% CI, 1.49-7.96). No increase was observed in children aged 2-5 years. Low vitamin C intake was marginally related to self-reported current wheezing in children aged 6-16 years. Our results show that increased BMI may influence asthma prevalence in children, but further investigation is needed. Copyright 2004 Wiley-Liss, Inc.