Nicotinamide Riboside Supplementation in Chronic Kidney Disease

This study is testing whether a dietary supplement called nicotinamide riboside, (NR), can be used in adults with moderate chronic kidney disease. NR is a form of vitamin B3 that may help support cellular energy metabolism. The main goal of this study is to see whether it is feasible for people with chronic kidney disease to take NR daily, complete study visits, and follow the study procedures. The study will also explore whether NR chloride affects markers of mitochondrial health, small blood vessel function, and physical function. Participants will be randomly assigned to one of two treatment orders. One group will take NR first and placebo second. The other group will take placebo first and NR second. Placebo looks like NR but does not contain active NR. Each treatment period lasts 12 weeks, with an approximately 2-week washout period between treatments. Neither participants nor the study team will know which treatment participants are taking during each period. Study visits will include blood and urine collection, physical function testing, and noninvasive tests of small blood vessel function. The study will enroll up to 36 adults with moderate chronic kidney disease at the University of California, San Diego.

Inclusion Criteria: * Moderate chronic kidney disease not treated with dialysis, defined as eGFR 30-59 mL/min/1.73 m2 using the CKD-EPI equation. * Urine albumin-to-creatinine ratio (uACR) \170 mmHg or diastolic blood pressure \>100 mmHg. * Current participation in another interventional trial. * Use of immunosuppressive medications, including steroids or calcineurin inhibitors. * Malignancy requiring active treatment or currently under surveillance at the discretion of the investigator. * Hospitalization for myocardial infarction, unstable angina, cerebrovascular accident, or unstable cardiac chest pain within the prior 3 months.