Asthma Obesity

Both asthma and obesity are sharply on the rise in the Western world. But why is there reason to think that there is a causal relationship between the two conditions? A number of research studies have suggested that there may be a link between obesity and asthma. However, although results from the latest studies show some association between weight and the incidence of asthma, there are several inconsistencies.

Recent Asthma and Obesity Studies

An American group, a Swedish group and an Australian group each published one of three recent studies on the link between asthma and obesity. The study, published in the American Journal of Epidemiology, was based on data from 3,792 children in Southern California. It reports an association between a body mass index (BMI) greater than the 85th percentile and the risk of developing asthma. Additionally, overweight boys in the study showed an increased risk for developing asthma.

The Swedish study, published in Acta Paediatrica, looked for an association between BMI and asthma in 457 sixth-grade children. The study concluded that there was a clear relationship between high BMI ratios and the presence of wheezing and asthma, supporting the results from the American study. However, no distinction was made as to whether boys were at a higher risk than girls.

In the Australian study, published in the journal Thorax, 5,993 Caucasian children ages seven to twelve were examined. This study, much larger than the two previously described studies, concluded that BMI is not a risk factor for asthma in boys or girls.

Which Study was Correct?

The different outcomes from the three studies may seem perplexing. In addition to the studies listed here, additional data has been gathered to supports an association between asthma and obesity and to reinforce the incidence of asthma is higher among women than men.

However, an analysis of the 2000 Behavioral Risk Factor Surveillance System data points out a strong positive association between BMI and asthma, not only among women, but Black and Hispanic men as well. The analysis, published in the Annals of Epidemiology, suggests that ethnicity may have something to do with the inconsistent results presented in the above studies. Consequently, race should be factored into any future studies.

Dietary Fat: The Missing Link?

Does the same component of our diets that fosters weight gain directly contribute to the development of asthma? What about the role of a low-fat diet in reducing both obesity and asthma symptoms? Some evidence suggests that managing the amount and/or type of fat in our diets may reduce the symptoms of asthma.

An analysis of the scientific literature by Spector and Surette in the Annals of Allergy, Asthma,