A few shakes a day? Are you serious? Along with meals? No, it isn't perfectly safe, as I already mentioned. It does lead to kidney damage. It's only worth it if the huge muscles are going to lead to Arnold Schwarzenegger bucks, but he's suffered from kidney problems and is so full of steroids I'm surprised he hasn't exploded. His butt has so many injections in it it must look like a pin cushion. And remember, a serious body builder eats six times a day, with lots of protein at each feeding. Now, one shake a day, maybe two, probably better, but a few? Can't agree here, and I did this for a living.
Protein is perfectly safe, and is very good for adding muscle, if not used in excess. Simply taking a few shakes a day to help get in your required protein will not harm you, but will be beneficial. But its better for you to take your doctors advice before you start taking your supplements.
I would not try them, as our friend, Pax said, there can be a price and it can be a very dangerous price at that. I have never trusted things like this. If you feel you have to take them, make sure you ask a good, nutritionally orientated doc, they may be able to help, but still, I would be leery.
Go get 'em, Pax! He knows, too! I'd listen to him if I were you. Don't play around with your health....
A serious body builder eats six times a day, so taking extra protein is hardly likely to cut into nutrients. However, body builders can pay a severe price by trying to get bigger. We've seen this with speed to help them endure longer workouts, steroids, and too much protein, which promotes kidney damage. There's no doubt a good quality protein supplement will help build bigger muscles -- the best is a good whey protein isolate, but there might be a reaction to the dairy -- but yes, you might pay a price. It depends of what you prefer, big muscles or health. The workout is fine, but taking any supplement that exaggerates intake of any nutrient so you get bigger muscles from that workout could lead to problems way down the road.