First, liver harm from anabolic steroids comes principally or entirely from alkylated anabolic steroids. Where the steroids are non-alkylated and estradiol levels remain normal, there’s almost never harm to the liver from steroid use. (A handful of apparent cases exist in the medical literature, so I don’t rule out that it could occur in very rare cases.)
Example non-alkylated steroids are testosterone, Masteron, trenbolone, boldenone (Equipoise), Deca Nandrolone Decanoate, and Methenolone Enanthate Primobolan depot Injection.
Keeping liver safety in mind, an effective cycle should have one or more of these steroids as the base, or even as the entirety of the cycle.
About 350-700 mg/week of a steroid stack, though, may be an alkylated compound. The most common alkylated steroids are Dianabol, Anadrol Oxymetholone, Anavar Oxandrolone and Winstrol.
Alkylated steroid use is preferably limited to only six weeks at a time, though of course many who go longer don’t suffer lasting harm. However, sustained use of oral anabolic steroids absolutely can cause undetected formation of scar tissue in the liver. This effect can be cumulative, as the scar tissue does not heal. And thoroughly excellent gains can be achieved without “pushing” the 6-week rule.
If cycle length is greater than 6 weeks, then appropriate amounts of testosterone can substitute for the orals. I replace Anadrol or Winstrol with testosterone on a milligram for milligram basis. I replace Dianabol on a three-to-two basis, or in other words, 50 mg/day Dianabol is replaced by about 75 mg/day of testosterone.
Oxandrolone, on the other hand, is replaced with Masteron on a three-to-two basis, or trenbolone on a two-to-three basis.
Each period of alkylated steroid use should be followed by about twice as much time not using alkylated steroids, or longer.
Estradiol preferably will be kept in the normal range, or not much above it, as elevated estradiol is slightly liver toxic. In and of itself estradiol toxicity is not greatly important, but in combination with alkylated steroid use, it adds to the toxicity.
Obviously hepatotoxic drugs and excessive alcohol use should be avoided, as should heavy use of NSAID’s, aspirin, or acetaminophen. Cautious use is fine.
In terms of supplementation for liver health, lecithin may be taken in amounts such as 3-7 g/day together with B vitamins. With regard to milk thistle, steroid-induced cholestasis results from reduced activity of the bile salt export pump, and silymarin and silibinin (components of milk thistle) act at this point and can partially block the adverse effects of steroids. However, cheap milk thistle products don’t provide much of these substances. As for liver antioxidants, the problem does not seem to be one of oxidation and I don’t think they make a difference.
Liver protection supplementation may safely be omitted when the above principles are followed. Supplementation shouldn’t be a license to use alkylated steroids less carefully. I would treat supplementation only as a backup.