Indices of body composition as predictors of immune and inflammatory responses and implications for health

The accurate measurement of body composition in humans is pivotal to understanding the links between excess adiposity and metabolic abnormalities. The potential mechanisms linking obesity to ill-health have been the focus of obesity research including the more recent investigations between obesity and both vitamin D status and inflammation. The aim of this thesis was to investigate a number of indices of body composition as predictors of immune and inflammatory responses, and their implications for health across different subgroups of the population. The effect of adiposity on vitamin D status was examined in healthy adults in a 22-wk randomised- controlled intervention. Vitamin D status was inversely associated with adiposity at baseline, however, only BMI was inversely associated with the change in vitamin D status following supplementation (151lg vitamin D3/d). These findings were only demonstrated in older adults ~64yrs), but not in younger adults (20 -40yrs). The associations between indices of body composition and metabolic parameters [lipid profile, insulin resistance (Ik) and inflammation] were investigated in two groups of healthy, young adults: men and women (20-40yrs) and men (18-30yrs). Body composition was a strong predictor of lipid profiles and glucose metabolism in these groups, however in terms of inflammation, it was only predictive of CRP and adiponectin. Although the strongest relationships were observed with fat mass index [FMI (kg/m2)], BMI proved in most cases to be almost as strong a predictor of metabolic risk factors in healthy individuals, and therefore remains a useful and appropriate surrogate measure of adiposity. The measurement of FM using more robust techniques should not be discounted, but, it is imperative that this is expressed relative to height, as FML as relying on the more commonly used indices of FM (kg/%) may attenuate results.EThOS - Electronic Theses Online ServiceGBUnited Kingdo