Maintaining a healthy weight could prevent thousands of children from developing asthma, according to a study.
Researchers from Duke University in the US analysed health data for over 500,000 children in the US and found that obesity might be to blame for about a quarter (23 to 27 per cent) of children with asthma.
This could mean about 10 per cent of all kids ages 2 to 17 with asthma may have avoided the illness by maintaining a healthy weight, according to the study published in the journal Pediatrics.
"Asthma is the number one chronic disease in children and some of the causes such as genetics and viral infections during childhood are things we can't prevent," said Jason E Lang, an associate professor of pediatrics at Duke University.
"Obesity may be the only risk factor for childhood asthma that could be preventable. This is another piece of evidence that keeping kids active and at a healthy weight is important," said Lang.
For the study, researchers analysed data for 507,496 children from more than 19 million doctor's visits at six major children's health centres.
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The data were entered into a clinical research data network called PEDSnet between 2009 and 2015.
Those classified as having asthma had been diagnosed at two or more doctor's appointments and had also received a prescription, such as an inhaler. Tests of their lung function also confirmed they had the disease.
Children classified as obese had a 30-per cent increased risk of developing asthma than peers of a healthy weight.
Asthma did not affect just those with obesity. Children who were overweight but not obese (BMI in the 85-94th percentile) also had a 17-per cent increased asthma risk compared to healthy-weight peers.
The researchers calculated asthma risk using several models and adjusted for risk factors such as sex, age, socioeconomic status and allergies. The results remained similar.