what jipped said is 100% on point. it is the most studied and researched supplement on the market. it even provides some heart health protections. now with that said, if i had serious kidney issues like kidney disease or kidney failure i may not use it. not saying i wouldnt but i would def talk to a modern level headed kidney doc before possibly putting more stress on my kidneys. that would be just out of over cautiousness. i got a buddy that has only one functioning kidney and it's function is semi-compromised and he still uses hrt plus and creatine and other supplements with no issues but that's not to say he is the rule and not the exception