Childhood overweight/obesity and asthma: is there a link? A systematic review of recent epidemiologic evidence.

Asthma and overweight/obesity prevalence are both increasing worldwide. Overweight/obesity has been suggested as a risk factor for developing asthma. The aim of this review is to present and evaluate recent publications that help answer the question: "Is increased body weight (at least overweight status) related to asthma in children?" A systematic review of epidemiologic literature was carried out using the MEDLINE database. Epidemiologic studies on young human subjects (ie, infants, children, and adolescents), published in English during the period 2006-2011 were included. A comprehensive literature search yielded 434 studies for further consideration. Forty-eight studies fulfilled the review's eligibility criteria. Two researchers applied the MOOSE Guidelines for Meta-Analysis and Systematic Reviews of Observational Studies on all identified studies. Current evidence supports a weak yet significant association between high body weight and asthma. New information indicates that central obesity in children increases asthma risk. Also, the link between high body weight and asthma may be stronger in nonallergic asthma. There are mixed results about the importance of sex. Although the nature of the association between overweight/obese status and asthma remains unclear, prospective studies point that high body weight precedes asthma symptoms. These data add weight to the importance of preventing and treating a high body weight against asthma outcomes. Available research in children has not studied adequately the influence of weight change (either gain or loss) on asthma symptoms, an area of clinical importance. Beyond energy control, the role of diet as a possible inflammatory stimulus warrants further investigation. Limited data seem to favor the promotion of breastfeeding in attenuating the overweight/obesity-asthma relationship. Finally, future research should include weight intervention studies assessing various measures of body fat in relation to well-defined asthma outcomes.