Obesity in Children May Contribute to Asthma

Asthma risk in children may rise as body mass index increases

(RxWiki News) Worldwide, children are experiencing higher rates of obesity. Obesity is tied to many health risks, including heart problems and diabetes. It may also be a cause of asthma in many young people.

A new study has found that a rise in body mass index (BMI) may be connected to an increased likelihood of getting asthma.

BMI is a measure of body fat based on height and weight.

Currently, an estimated 7.1 million children under the age of 18 have asthma, a chronic disease that inflames and swells the airways. Just as the number of young people with asthma is growing, so is the obesity rate among children and teens.

"Encourage children to exercise and maintain a healthy weight."

Raquel Granell, PhD, a research fellow specializing in epidemiology of asthma and allergy in children with the School of Social and Community Medicine at the University of Bristol in the United Kingdom, led this investigation to see if there may be a causal link between obesity and asthma.

Using a method called “Mendelian randomization,” Dr. Granell and her colleagues analyzed both genetic information and observational data on 4,835 children in the United Kingdom at age 7.5 years in order to assess whether BMI had a causal effect on asthma.

These researchers developed a weighted genetic score based on 32 DNA sequence variations related to BMI. They also estimated associations with BMI, fat mass, lean mass and asthma.

Based on these calculations, the researchers estimated that the relative risk of asthma climbed by 55 percent for every extra unit of BMI.

While asthma may be related to obesity-induced inflammation, the researchers pointed out that body composition may influence asthma in other ways, but more study is needed.

"Environmental influences on the development of asthma in childhood have been extensively investigated in epidemiological studies, but few of these provide strong evidence for causality," the authors wrote.

“[Higher BMI in mid-childhood] could help explain some of the increase in asthma risk toward the end of the 20th century, although the continued rise in obesity but with a slowing in the rise in asthma prevalence in some countries implies that other non-BMI-related factors are also likely to be important," they wrote.

The Centers for Disease Control and Prevention (CDC) reported that obesity has more than doubled in children and quadrupled in teens over the past 30 years. The percentage of obese children ages 6 to 11 in the US jumped from 7 percent in 1980 to almost 18 percent in 2012. Obese teens (ages 12 to 19) rose from 5 percent to nearly 21 percent over the same time period.

These results from this study suggest that a higher BMI may raise the risk of childhood asthma, according to Dr. Grannell and her team. These researchers wrote that public health interventions designed to lower obesity may also help to inhibit the rise in asthma worldwide.

This study was published in July 1 in PLOS Medicine.

Support was provided by the UK Medical Research Council and the Wellcome Trust and the University of Bristol. One contributing author is a member of the editorial board of PLOS Medicine.

Review Date: 
July 1, 2014