Nicotinamide riboside tartrate (NRT) is an oral NAD+ precursor that raises NAD+ levels, activates SIRT1 and SIRT3, and serves as a vitamin B3 (niacin) source. NRT also improves oxidative metabolism and protects against metabolic abnormalities induced by a high-fat diet. Furthermore, NRT mitigates cognitive decline in a transgenic mouse model of Alzheimer's disease.