The bit I got from health.nytimes.com:
Our liver is involved in the conversion of food into energy. A damaged liver cannot function normally therefore diet modification is essential. In those with a severely damaged liver, protein is not processed efficiently, therefore protein restriction is recommended. Control salt intake (especially if there's fluid retention). Carbohydrate should be the main contributor of calories, and moderate fat intake (to preserve protein in the body and prevent protein breakdown).
nwhealth.edu and liverdoctor on liver supplements:
Milk thistle, alpha lipoic acid, licorice extract, dandelion, turmeric, artichoke, flaxseed oil, vitamin K, arginine, selenium, essential fatty acids, among others.
I can go on and on but I'm not writing a thesis here. Plus these info are very minimal. Further reading and pondering and research are needed for a really complete write-up. The info here is very basic and BIL and his friend can surely continue on from here.