 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. 