My experience is that I ate 200-350 grams of protein for 14 years, and it cause me moderately severe kidney malfunction.
And it took several years of trail and error to correct these problems.
I don't have a particularly high rate of protein synthesis, so, IMHO, that contributes to a higher amount of protein waste which has to be processed and eliminated thru the liver, kidneys, and exit via the bladder and bowels.
The more protein consumed but not converted to muscle, just ends up as another waste product that the body has to filter out of the blood and eliminate from the body.
The first thing that I had to do was to drop my protein intake to 50grams/day. Any more than that and the body has to pull calcium out of the blood, body, organs and bones to try to try to balance your body's ph levels(because protein is acidic).
And this is a pretty easy amount of protein for the body to hand, for most people.
Also, I went vegetarian for a couple of months, including veg protein(RAW MEAL and RAW PROTEIN by Garden of Life on Amazon, helped me a lot. NO SOY PROTEIN, IT'S CRAP, and harder on your body)
This was a turning point for me in healing because it helps shift the body's ph to be alkaline which is much more beneficial to healing.
I was an idiot for not doing this much sooner.
Also, water purified with a quality home filter is a must, but not that bottled water crap, it's FULL of contaminates.
About 1 gallon a day for me now, but at first I had to decrease it some because it was working my kidney even more having to pee all the time, because I really cleaned everything up and actually needed less water that I was accustomed to drinking.
Do a great liver cleanse, I have an easy one that works great that I'll be glad to post up.
When your liver is full of crap and sluggish it can't do its job, and guess what else has to work HARDER.
Yep, your kidneys!!!
And you MUST KEEP YOUR BOWELS RUNNING REGULAR!!!
If you don't, your asking for more problems, because this makes the metabolic waste products back up in your blood and it has to be re-filtered by the liver and kidneys.
Anyway, I could go on and on, and if your want more info please pm me and I'll fill you in on what else I did.
My opinion is that very high protein consumption for long term, is going to come back and bite you, and I've found that most of that extra protein just simply is an unnecessary waste and potential hazard.
My norm now is about 100 grams per day, which is .5/body pound, less on non workout days usually.
As long as I'm training and sleeping adequately I don't seem to have any problems. 8)