The Relation Between Obesity, Adipose Tissue Content of Fatty Acids and Systemic and Airway Inflammation

Cross-sectional studies in Northern America, Northern Europe and Asia indicate an increased prevalence and severity of asthma in the obese whereas longitudinal studies have indicated that increasing BMI is associated with increased risk of incident asthma in women. However, the mechanisms through which where-by obesity increases the risk for asthma remain unclear. There are only few studies from North America and Asia that suggested that obesity is associated with increased skin test reactivity and atopic diseases and many more that suggest obesity has no association with atopy. In adult asthmatics, it has also been shown that both medical and surgical weight loss is consistently associated with dramatic improvements in lung function, asthma symptoms, and medication usage. However, in children no study has elaborated on the potential benefits of reducing weight.

Total fat intake has also been associated with the diagnosis of asthma. N-3 fatty acids have been noted to inversely correlate with body fat, while levels of N-6 fatty acids correlated positively with body fat. Increased dietary intake of N-3 fatty acid (such as eicosapentaenoic acid) (mainly fish oils) has been generally associated with protection from asthma, while intake of N-6 fatty acids (such as linoleic acid) may increase asthma risk, although this remains controversial. Linoleic acid may act as a precursor of arachidonic acid which subsequently serves as a precursor of 4-series leukotrienes that are highly active mediators of inflammation.

There are only two studies that investigated the levels of exhaled nitric oxide (ENO) as indicator of airway inflammation in relation with obesity and asthma. One study showed significant increase of ENO with increasing BMI in healthy adults. However, the levels of ENO and exhaled leukotriene B4 were recently found to be increased in lean and obese asthmatic children but not related to their BMI's.

In Southern European countries, there are no representative epidemiological data on the contribution of obesity to asthma burden. In this area of the world, there are also no studies on the effect of important lifestyle factors including diet and physical activity on the association of adiposity with asthma pathophysiology. In addition, no information exists on levels of airways inflammation both in non-asthmatics and asthmatics subjects in relation to body content in fat and the impact of weight reduction on airway inflammation.

In years 2001-2003, a national health survey was conducted in Cyprus focusing on nutrition and physical fitness of all children aged 11-12 years (attending the 6th form of all primary schools). With this project we proposed to approach this group of children in years 2007-2009 to investigate the following hypotheses: