According to the U.S. Department of Veterans Affairs, the liver is one of the only organs in the human body capable of replacing damaged tissue. This repair can be slowed or prevented by infection or by drug or alcohol abuse.
The liver functions as a filter for the blood and also stores useful nutrients to be released into the bloodstream when needed. When the liver fails to repair itself, the resulting scar tissue can eventually become cirrhosis, according to Addiction and Recovery. As the human body contains, on average, 30 percent more liver tissue than is needed, some patients with permanent liver damage can still lead normal lives.