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.
This research showed that early abnormalities in lipid and/or glucose metabolism may be associated to the development of asthma in childhood. These 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 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 18000 children who were 4 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.
The result was 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 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 the degree of physical activity may be as important as nutrition; these 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, animal studies 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.
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. There are 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. ( Xagena )
Source: American Thoracic Society, 2010