The invention relates compositions and methods of prolonging the lifespan of a subject or providing anti-aging benefits. A method of the invention comprises administering an agent that inhibits the conversion of cysteine to cysteine sulfinic acid to a subject, for example using an inhibitor of cysteine dioxygenase (CDO). A composition of the invention may comprise a) a CDO inhibitor； and b) a second agent known to be useful in prolonging the lifespan of a subject or preventing or reducing age-related symptoms. Also provided is a CDO-based screening method for identifying a compound capable of prolonging the lifespan of a subject or preventing or reducing age-related symptoms in a subject.
