I've been reading on diet-i.com that too much protein in your diet can cause damage to your liver. Is this true? Are there any tablets or supplements that cancel out the negative effects?
As far as I know, a high protein diet will not cause any liver damage. I've gone as high as 2x bodyweight in protein per day, and liver values were always normal. As long as your water intake is high, there shouldn't be any problem.
too much of anything has a potential to kill you, let alone damage your internal organs
But sawastea is correct protein substrates and products of proteolysis (protein metabolites) will primarily affect kidney function (since it filters and excretes these metabolites/byproducts) - however, the amount of protein has to be exorbitant for an extended period of time, or another possibility a genetic predispostion/existing irregularities in internal functioning which could be aggravated.
Also liver enzyme elevation is a viable undergoing, especially in light of intense training (once again protein breakdown moreso than actual intake is what matters really)
Also too, your going to have to be consuming a large amount of protein at one time. As long as you don't sit down and eat 200 grams of protein at one time you'll be fine.