Boosterspice

In Larry Niven's fictional Known Space universe, boosterspice is a compound that increases the longevity and reverses aging of human beings. With the use of boosterspice, humans can easily live into hundreds of years and, theoretically, it can extend life indefinitely.

Humans have been led to believe it is made from genetically engineered ragweed (although early stories have it ingested in the form of edible seeds) but, in Ringworld's Children, we discover it is actually adapted from Tree-of-Life, without the symbiotic virus that enabled hominids to metamorphose from Pak Breeder stage to Pak Protector stage (mutated Pak breeders were the ancestors of both homo sapiens and the hominids of the Ringworld in the Known Space universe).

On the Ringworld, there is an analogous compound, but they are mutually incompatible; In The Ringworld Engineers, Louis Wu learns that the character Halrloprillalar died when in ARM custody after leaving the Ringworld, as a result of having taken boosterspice and previously having used the Ringworld equivalent.