Effects of Pomegranate Supplementation on Physical Function and Cardiovascular Disease Risk in Chronic Kidney Disease Patients

Chronic kidney disease (CKD) patients have very low physical function and high rates of cardiovascular disease (CVD) mortality. The objective of the proposed research is to evaluate the effects of dietary supplementation with a pomegranate extract, that contains high amounts of antioxidants, on physical function and CVD risk. Patients with moderate to severe chronic kidney disease that are NOT yet on dialysis tend to have significantly reduced risk factors for cardiovascular disease (and other disorders) compared to dialysis patients. This includes significantly reduced systemic markers of oxidative stress and inflammation. As a result, therapies designed to reduce the risk of CKD co-morbidities may differ significantly in dialysis and pre-dialysis patients. For example, dialysis patients are recommended to INCREASE their intake of dietary protein, while pre-dialysis patients are recommended to DECREASE their protein intake, due to differences in the pathophysiology of the two conditions. The investigators have decided to recruit pre-dialysis patients in addition to dialysis patients in this study because the investigators believe this will help us determine if the efficacy of pomegranate differs between patients with different stages of CKD. CKD patients will be recruited under 2 phases: CKD patients not receiving dialysis treatment (pre-dialysis patients) will be recruited in the first phase. This will include patients with CKD stage 3-5 that are not yet on dialysis. In the second phase, only CKD patients on dialysis treatment will be recruited. To address these questions, CKD patients will be randomized to the following groups for 12 months: 1) no POM supplementation/control (CON), and 2) oral supplementation with purified pomegranate extract (POM). Patients in the POM group will ingest a 1000 milligram capsule of POM extract, 7 days per week. Patients in the CON group will receive a placebo capsule using the same protocol. On three occasions, at baseline, 6, and 12 months, each subject will have blood collected to measure plasma markers of oxidative stress (TBARS, lipid peroxides), blood lipid levels, and glucose and insulin levels. Arterial and cardiac structure and function will be measured by vascular ultrasound and echocardiogram, respectively. A 24-hour dietary recall will be used to assess the intake of nutrients. Leg strength will be measured on a resistance exercise machine. Bone density and body composition will be evaluated using dual energy x-ray absorptiometry (DXA). Pre-dialysis subjects will undergo a maximal exercise test to assess their cardiorespiratory fitness level. In dialysis patients, instead of a maximal exercise test, physical function will be measured by a 6-item functional fitness assessment and a 10-meter walk test.