Graduation Date

Summer 8-14-2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Programs

Epidemiology

First Advisor

Dr. Shinobu Watanabe-Galloway

Abstract

Metabolic syndrome (MetS) is a cluster of metabolic disorders, including increased fasting glucose, blood pressure, plasma triglyceride, reduced high-density lipoprotein cholesterol and abdominal obesity. It leads to an increased risk of cardiovascular disease and diabetes. The growing prevalence of MetS is strongly related to the increasing prevalence of overweight/obesity. As an antioxidant, lycopene can reduce the risk of MetS. However, it is unclear whether lycopene has similar effects among overweight/obese individuals and whether lycopene can reduce the risk of mortality among individuals with MetS. The purpose of this study was to explore the roles of lycopene in the prevalence and mortality of MetS. Specifically, the main objective was to examine the associations between serum lycopene or the ratio of serum lycopene to serum triglyceride and MetS, and the association between the ratio and mortality among individuals with MetS. In addition, the possible additive effects of physical activity and lycopene on MetS and mortality were studied. To achieve these objectives, analyses were conducted with participants aged 20 years and older from the NHANES 2001-2006. The tertile rank method was used to divide participants into three groups according to serum lycopene or the ratio. Logistic regression and Cox models were used for association analyses. With serum lycopene, the associations between lycopene and MetS were only significant for normal weight/overweight (p<0.05), but not for obese participants (p>0.05). While with the ratio, the associations between lycopene and MetS were significant not only for normal weight/overweight (p<0.05), but also for obese participants (p<0.05). Compared with the first tertile group, both the third and second tertile groups had significantly reduced hazard ratios of mortality for participants with MetS. The additive effect of lycopene and physical activity was significant for overweight (p<0.05) but not for obese participants (p>0.05). There was no an additive effect of lycopene and physical activity on mortality among participants with MetS. Therefore, the study adds new evidence that the ratio of serum lycopene to serum triglyceride has significant associations with morbidity and mortality of MetS.

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