The invention provides compositions for preventing or treating kidney disease and improving kidney function comprising at least two ingredients selected from the group consisting of antioxidants and mitochondrial cofactors in amounts sufficient for preventing or treating kidney disease or for improving kidney function and methods for preventing and treating kidney disease or improving kidney function comprising administering such compositions to an animal susceptible to or suffering from kidney disease or impaired kidney function. In a preferred embodiment, the composition is admixed with one or more food ingredients to produce a food composition useful for preventing or treating kidney disease and improving kidney function, particularly in senior animals.