A US study has suggested that the increase in childhood asthma may be explained by the rise in obesity, rates of both have shot up dramatically in recent decades in the West. Over 6million people are currently being treated for asthma, compared to 3.4m in 1999.
The researchers found the fattest children were 77% more likely to have asthma symptoms.
They suggest increased weight might lead to inflammation in the respiratory tract, which could be the key factor in inducing asthma. Appropriate strategies for the reduction of body weight in children may contribute to a reduced incidence of asthma in childhood, says Dr.Erika at University Children's Hospital, Munich.
The way weight affects the lungs could also affect the airways, leading to a child developing asthma symptoms. The mechanical impact of the weight on the lungs could compromise the airways, causing increased responsiveness which is a hallmark of asthma, the researchers add.
Seven thousand children, aged between four and 17, took part in the US National Health and Nutrition Study, which began in 1988 and was carried out over six years. Parents were asked about factors including children's exposure to tobacco smoke, their birthweight and if they were breastfed, factors which could have affected their asthma risk. Heights and weights were measured, and their body mass index calculated.A BMI over 30 is considered as obesity.
The team, led by Dr Erika von Mutius, of University Children's Hospital, Munich, Germany wrote: "BMI may be an independent risk factor for the development of asthma. However, researchers from the Department of Public Health Sciences at King's College, London say the link between obesity and asthma is recent.