An article about risks associated with excess protein consumptionhttp://www.acefitness.org/fitnessqanda/fitnessqanda_display.aspx?itemid=272
In addition to what is mentioned in this article, excess protein may cause harm in individuals with certain kidney diseases. These individuals are placed on protein restriction..diabetic kidney disease is a common one
Protein is not usually harmful to the liver. In some individuals with severe disease, protein is restricted.
Anabolic steroids, human growth hormone, and insulin have potential to cause problems
creatine, glutamine are safe
I'm not familiar with other supplements and particular brands..my concern is that these products have not been scientifically tested for efficacy and safety...supplements are not regulated by the FDA...an example would be Hydroxycut