. "Are you familiar with the reason why they cannot convert beta-carotene into Vitamin A? Also, how is it in the wild, they satisfy their need of Retinol? As a chameleon keeper, this topic seems to be controversial among people. Is there a more thorough study that addresses this matter?"
"I don’t know why the carotene in carrots couldn’t be converted. It could be that other carotenes in the guts of wild plant-eating insects can be. It could also be why panthers sometimes occasionally eat lizards and nestling birds, which should be a good source of retinol. I think it is a good idea to feed panthers large pinkies or small lizards, such as anoles, occasionally, if they will eat them. There indeed needs to be more study on this subject."
taken from- chamworld.blogspot.com