January 2013 Summary

Childhood Overweight/Obesity and Asthma: Is There a Link? 

A Systematic Review of Recent Epidemiologic Evidence

     The prevalence of overweight/obesity and asthma have increased concurrently in the past two decades. Asthma affects approximately 9.1% of children  0-17 years old in the U.S. Longitudinal studies agree that overweight/obese children are more likely to experience asthma symptoms compared to a normal weight child and also, that overweight or obesity was already evident prior to the child developing asthma. It is suggested that asthma secondary to overweight/obesity may be more difficult to manage. Possible explanations that link asthma to a higher body weight include changes in airway response, change in physical activity and diet, increased insulin resistance, systemic inflammation and mechanical changes related to increased body weight.

     This month’s article is a review of the recent research on the relationship of body weight and asthma in children. The results of 48 cross-sectional, case-controlled, and longitudinal studies almost unanimously supported the relationship between increased body weight and asthma in children.  One pediatric study examined the timing of a higher BMI and risk of asthma. A high BMI in infancy was correlated with a reduced risk of asthma whereas a high BMI at 5 years old is associated with greater risk of asthma and declined lung function. This difference is greatly due to the growth of lean mass seen in infancy which is positively correlated to respiratory health. The development of an increased BMI at 5 years old is likely due to the growth of fat accumulation which is negatively correlated to respiratory health. In a different study, BMI specifically was not associated with asthma, however, central obesity was. This study used a framework that linked a high caloric/Western diet with a higher visceral fat deposition, inflammation, and insulin resistance which ultimately led to increased asthma risk. One of the major limitations of the studies reviewed in this article was the absence of distinguishing underweight children from normal weight children.  Differentiating these two weight groups in the future could identify the effect of being underweight on asthma symptoms.

     A high body weight is associated with dyslipidemia and hyperinsulinemia which are problems that can influence the respiratory tract. In several studies looking at asthmatic children, obese children had a significantly higher prevalence of metabolic syndrome compared to normal weight children.  These studies concluded confidently that hypertriglyceridemia and insulin resistance were positively associated with asthma whether or not obesity was present. A study found that airway inflammation was negatively associated with plasma MUFAs and positively associated with plasma saturated fatty acids. Diet was briefly mentioned in the article and proposed fresh seafood, fresh fruits and vegetables were correlated with reduced asthma symptoms and that the typical low-quality “Western” diet may induce an inflammatory response.  

Papoutsakis, C., Priftis, K.N. , Drakouli, M.,  Prifti, S.,& … Matziou, V. (2012).  Childhood overweight/obesity and asthma: is there a link? A systematic review of recent epidemiologic evidence. Journal of the Academy of Nutrition and Dietetics, 113(1), 77-105.

Adherence to the Mediterranean type of diet is associated with lower prevalence of asthma symptoms, among 10–12 years old children: the PANACEA study

     Very little was discussed about diet and asthma in the aforementioned article so this article was chosen to supplement it. This study focused on examining the relationship between the Mediterranean diet and childhood asthma. The Mediterranean diet, traditionally consisting of vegetables, legumes, fruit, fish and olive oil has been a model for healthy eating due to its low prevalence of diseases and illnesses when compared to Western or European diets. Several studies have shown that a diet high in fruit, vegetables and fish may be associated with a reduced risk of asthma.

     The sample included 700 10-12 year old children living in Athens. Children and parents filled out a questionnaire covering the child’s dietary habits and asthma. The dietary habits were scored based on adherence to the Mediterranean diet and asthma severity was scored based on symptoms. The results showed that a strong, inverse relationship between level of adherence to the Mediterranean diet and prevalence of asthma was observed. This article agrees with several other studies in that adhering to the Mediterranean diet, especially fish and seafood consumption, early in life can protect against developing asthma.

Arvaniti, F., Priftis, K. N., Papadimitriou, A., Papadopoulos, M., Roma, E., Kapsokefalou, M., &… Panagiotakos, D. B. (2011). Adherence to the Mediterranean type of diet is associated with lower prevalence of asthma symptoms, among 10-12 year old children: the PANACEA study. Pediatric Allergy & Immunology, 22(3), 283-289.