Childhood asthma is on the rise and so is obesity. Is there a link between the two? Approximately 17% of US children age 2-9 are obese. These children are increased risk for developing asthma. Childhood asthma accounts for 14 million missed school days a year. Despite the link, a definitive mechanism remains unknown.
Although genetic susceptibility can contribute to asthma and obesity, there are other lifestyle changes that play a role. Diet, physical activity, early life exposures, all can play a role. Diet and nutrition, especially prenatal may play a role. Greater consumption of fruits, vegetable, fish an legumes during pregnancy seems to confer protection against asthma. It also may have a role in shaping the immune system and lung development.
Physical or mechanical effects are likely to play a role in childhood asthma and obesity. Most data show a decrease in lung capacity and volume in adults because of elastic changes in the chest wall.
Airway hyperresponsiveness does not seem to play a significant role as studies have failed to show any difference in prevalence between obese children and and normal-weight children with asthma after an exercise challenge test.
Increased inflammation has been proposed as a possible link between childhood asthma and obesity. Data is conflicting regarding this. Adult studies to show some role, but more work needs to be done in children.
There is no doubt that an association does exist between obesity and asthma. It seems more likely that the obesity predates the onset of asthma. The connection is likely due to more than one entity. Non-inflammatory conditions are emerging as a cause in obese mouse models resulting in airway bronchoconstriction.
Pediatric obese asthma continues to rise in the United States and we need to improve their asthma management as a whole. We need to completely understand the relationship between asthma and obesity. Additional studies are needed, but a link between genetics, lifestyle and mechanical effects play a role. Although inflammation does play a role in adults, the data on children is conflicting.