Milk thistle was highly regarded and used by bodybuilders and health food fans for a long time. it's included in many liver protection formulas, but...
the most recent macro studies (a study of studies) say that milk thistle probably isnt a good bet if you're looking for liver protection.
according to the results, they were unable to establish any liver protection benefits compared to controls as measured by liver enzymes, and they were unable to exclude the possibility of harmful side effects.
doesnt sound like a good cost-benefit ratio to me.
R-ALA - r-alpha lipoic acid - - r-alpha lipoic acid - - on the other hand has solid science demonstrating its liver protection and regeneration benefits. it also has many other health benefits especially useful for a bodybuilder (carb management, antioxidant,). NAC is also a solid addition with many benefits beyond liver support.