Imbalanced diet and inadequate exercise may underlie asthma in children

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American Thoracic Society

Imbalanced diet and inadequate exercise may underlie asthma in children

Even children of a healthy weight who have an imbalanced metabolism due to poor

diet or exercise may be at increased risk of asthma, according to new research,

which challenges the widespread assumption that obesity itself is a risk factor

for asthma.

" Our research showed that early abnormalities in lipid and/or glucose metabolism

may be associated to the development of asthma in childhood, " said lead author

Giovanni Piedimonte, M.D., who is professor and chairman of the Department of

Pediatrics at West Virginia University School of Medicine, physician-in-chief at

WVU Children's Hospital and director of WVU's Pediatric Research Institute. " Our

findings also imply a strong and direct influence of metabolic pathways on the

immune mechanisms, both innate and adaptive, involved in the pathogenesis of

asthma in children. "

The research, which was published online ahead of the print edition of the

American Thoracic Society's American Journal of Respiratory and Critical Care

Medicine, implicates metabolic disorders directly in the development of asthma,

and points to a new way of viewing diet and lifestyle as risk factors for

asthma, even in children who are not obviously obese or overweight.

The researchers gathered demographic data, estimates of body mass index (BMI),

and asthma prevalence on a sample of nearly 18,000 children from West Virginia

who were four to 12 years old and were participating in the Coronary Artery Risk

Detection in Appalachian Communities (CARDIAC) Project. Metabolic data was

available for all children in the study, and the researchers investigated a

suite of markers for early metabolic dysfunction, including triglyceride levels

and evidence of acanthosis nigricans (AN), a brown to black hyperpigmented skin

rash that is a biomarker for developing insulin resistance and hyperinsulinemia.

They found that while asthma prevalence generally increased with BMI, it was

significantly higher in obese and morbidly obese children than in children with

healthy BMI, but that simple overweight status did not appear to be linked to

increased asthma prevalence. However, after controlling for BMI and other

confounding variables, asthma prevalence was significantly associated with

triglyceride levels and the presence of AN independently of BMI.

" The metabolic problems we investigated may have confounded the widely

publicized epidemiologic link between obesity and asthma, because high

triglyceride levels (dyslipidemia) and AN (hyperinsulinemia) are very common in

obesity and metabolic syndrome, " said Dr. Piedimonte.

The results suggest that only above a certain threshold metabolic factors

participate in the disease process of airway inflammation and hyperreactivity,

which ultimately leads to asthma. More importantly, the association between

asthma, triglyceride levels and the presence of AN exists regardless of body

weight, suggesting that children who are a healthy weight, and even those who

are underweight, may be at risk for developing asthma because of a subtle

metabolic dysfunction leading to increased triglyceride levels and the presence

of AN.

" Both imbalanced nutrition and inadequate exercise may play a role in metabolic

syndrome, and our experience suggests that degree of physical activity may be as

important as nutrition, " said Dr Piedimonte. " Our present data suggest that

strict monitoring and dietary control of triglyceride and glucose levels

starting in the first years of life may have a role in the management of chronic

asthma in children. Furthermore, another paper just published by our group in

Pediatrics supports universal lipid screening rather than the current National

Cholesterol Education Program-recommended selective screening based on family

history of premature heart disease. The rationale is that by using selective

screening, we would have missed over a third of children with significant

genetic dyslipidemia. "

Furthermore, Dr. Piedimonte noted that animal studies recently presented by his

group suggest a link between maternal diets high in fat and calories, the

subsequent triglyceride levels of offspring, and the development of airway

hyperreactivity in early life, hinting at a potential role of maternal diet in

the prevalence of asthma in their offspring.

" The primary implication of the present study is that early metabolic

abnormalities induced by imbalanced diet during pregnancy and childhood

constitute the central hub from which the asthma-obesity-diabetes triad

originates, at least in a subpopulation of patients, " said Dr. Piedimonte. " This

opens a Pandora's box of questions concerning the role of pre- and early

post-natal nutrition as a critical determinant of chronic diseases throughout

life. The ultimate goal is to elucidate the chronologic sequence of early-life

events and the specific molecular mechanisms linking hypertriglyceridemia,

insulin resistance, and the inflammation seen in obesity and asthma, which may

open a new chapter in the management of these medical conditions that are among

the most prevalent today. "