I have used Liv52 and milk thistle on cycle. I have also run cycles without. I do lab work about every 3 months and I have honestly never seen a major difference. The most effective way to protect the liver is to be conservative with dosing and length of time on. In the off season, I dont use a lot of orals, as they are much harsher, both on the liver and on lipids. Maybe once a year, I will use dbol, as it is my favorite bulking drug, but even then, I am careful. I don't go crazy with the dose and don't stay on it for more than 6-8 wks per year. During contest prep, I leave the orals to the last 4-6 wks. 8 wks at most. The best way to know where you're at is to get lab work done!