n-3 polyunsaturated fatty acids, insulin sensitivity and inflammation

Obesity increases the risk of disease and inflammation may be an important mediator of this association. This thesis describes a series of studies that have investigated the relationship between obesity and its co-morbidities, using dietary fatty acids to modulate inflammatory status. Study 1 investigated the stability of a number of inflammatory markers used to characterise habitual inflammatory status in two populations of overweight and obese subjects. Results showed that sialic acid was the most stable representative marker of habitual inflammatory status, showing less variability than more commonly used markers such as C-reactive protein (CRP) and fibrinogen. This has important implications for future studies that characterise inflammatory status and relate inflammation to disease risk. Study 2 describes a cross-sectional analysis of 261 overweight and obese women where features of the metabolic syndrome were related to sialic acid and CRP. Sialic acid and CRP were univariately related to individual features of the metabolic syndrome. Sialic acid showed an incremental association with the number of features of the metabolic syndrome after adjustment for body mass index (BMI). CRP was strongly associated with BMI and did not independently predict features of the metabolic syndrome. This study showed that sialic acid identifies a group at risk of the metabolic syndrome independent of BMI. Study 3 was a crossover nutritional intervention study designed to test whether habitual inflammatory status influenced the impact of a dietary intervention. Subjects with a raised background inflammatory status at baseline showed a significant improvement in insulin sensitivity with 12 weeks n-3 polyunsaturated fatty acid intervention. These results show a small but significant improvement in insulin sensitivity with n-3 polyunsaturated fatty acid supplementation and that those individuals at the highest risk of metabolic syndrome derive the most benefit from intervention.EThOS - Electronic Theses Online ServiceGBUnited Kingdo