Water.
Read about a recent study that states that the average American ingests enough protein daily to cover the requirements of a professional bodybuilder. There's no need for extra.
Though that's for the average person. I'm sure Kupek's protein supplements are needed, being vegetarian. But for standard people, it's unnecessary.
"For one thing to live, another thing must be killed. God, or whoever is responsible, deserves respect for creating such a system. It reveals that we cannot take all matters into our own hands. We need only to focus on doing our best--a simple, yet profound way to live, is it not?"