Heinlein’s “Methuselah’s Children”, one of his books in the Lazarus Long universe, made the prediction that replacing old blood with new would have a rejuvena

Heinlein’s “Methuselah’s Children”, one of his books in the Lazarus Long universe, made the prediction that replacing old blood with new would have a rejuvenating effect. The book was published in the early paper-SF age, the 1940s/1950s.