Hmmm...well, I'm sure a lot of people will disagree but just to give you another point of view...I'm not really for protein shakes, supplements etc.
We really do take in more protein than we need (of course there are always exceptions such as athletes etc.). Here's some info I highlighted in my textbook.
According to the American Council On Exercise: "The principal role of protein in the body is to build and repair body tissues, such as muscles, ligaments and tendons. Protein is also important for the synthesis of hormones, enzymes, and antibodies, as well as for fluid transport and energy.
Contrary to popular belief protein is NOT a primary source of energy except when you don't consume enough calories or carbs. If you consume more protein than the body can use, the excess amino acids may be stored as fat. Available research suggests that an active adult only needs about .8 - 1.0 grams of protein per kilogram of body weight."
Probably more info than you wanted!!! LOL Sorry!
I'm just on one of the nutrition chapters this month and the info is floating around in my head! =)