One in 10 people have reduced lung function during childhood, which leads to compromised lung capacity in adulthood – putting these people at risk for serious health conditions, such as cardiovascular disease, lung disease and diabetes, according to the researchers. 

To try to quantify the link between lung function and childhood BMI, the researchers used data from a separate, ongoing study in Stockholm. They examined BMI measurements of 3,200 children taken 14 times between ages 4 and 14. They also looked at the lung function of these children at ages 8, 16 and 24, as well as urine samples. 

They found children with the highest BMIs had reduced lung capacity as adults, usually due to inflammation inside airways constricting airflow in and out of the lungs. The children’s urine samples also confirmed previous research that linked higher levels of certain metabolites to chronic obstructive pulmonary disease and asthma.

A stable or low BMI in childhood was linked to inadequate lung development and reduced lung function in adulthood.

“The focus has been on overweight, but we also need to capture children with a low BMI and introduce nutritional measures,” said Gang Wang, a researcher at Sweden’s Karolinska Institutet who led the study.

The research also found children who initially had high BMIs, but who achieved normal BMIs before puberty, did not have impaired lung function as adults.

“This highlights how important it is to optimise children’s growth both early in life and during their early school years and adolescence,” researcher Erik Melén, a professor of pediatrics at the Karolinska Institutet, said in a news release. 

Although the study established a correlation between childhood BMI and adult lung function, more research is needed to identify specific molecular links, according to the study.