Before revision: Elli is not mentioned in any other extant source but the notion that not even the gods are immune to the effects of aging is supported by the fact that they must consume the apples of Iðunn on a regular basis in order to remain young.
After revision: Elli is not mentioned in any other extant source but the notion that not even the gods are immune to the effects of aging is supported by the fact that they must consume the apples of Iðunn regularly to stay young.