1995, David Zeb Cook, Jean Rabe, Warren Spector, Dungeon master guide for the AD&D game (page 202)The standard ring of regeneration restores one point of damage per turn (and will eventually replace lost limbs or organs).
2003, Bastion Press, E. W. Morton, Out for BloodRegeneration does not restore hit points lost from starvation, thirst, or suffocation.