Why does the anime change the flashback in the Baratie arc?

I know this is like, ancient in the grand scheme of the whole of One Piece, but it's always been on my mind. In the manga and the Live action, in Sanji's flashback Red Foot Zeff eats his leg to stay alive. But in the anime, it gets caught in the ship falling and ends up getting cut off. In a series with human experimentation, slavery, child slavery, trafficking, etc, why is cannibalism, of all things a step too far? Even in that context, they were on that rock for nearly 50 days, if my count is correct, so he would have starved long before the confrontation of a feral, starving Sanji so it doesn't even make sense story-wise.