User blog comment:Xilinoc/Realistic One Piece/@comment-24769684-20150525202904/@comment-96.42.191.111-20150527012213

Though I doubt it would be so, I see no issue with it being the person dies of old age based upon the animal, but that age would be in the time they are that animal. So for any zoan, if they stay in the animal form for extended periods of time they risk reaching that limit. So a person that eats a zoan fruit as a child and spends half his days in an animal form could die from the animal old age by 30. Of course if you got a fruit like tortoise you could stay in the form extended periods of time since they live far longer than a human would anyways.