DEAR DR. ROACH: Any thoughts on milk thistle supplements in fatty liver disease that was diagnosed by an ultrasound due to elevated AST and ALT levels? — B.S. ANSWER: Milk thistle (sylmarin) has had mixed results in clinical trials regarding metabolic-associated steatotic liver disease (MASLD, formerly called fatty liver disease). Although a few individual trials have shown benefit, the major association for liver disease has concluded that sylmarin does not improve the condition as measured by biopsy, and they recommend waiting for larger trials before recommending this treatment.
When the diagnosis of MASLD is suspected due to elevated liver enzymes (ALT and AST are blood tests that look for damage to liver cells called hepatocytes), then a person should be examined for scarring and inflammation in the liver, which is a condition called metabolic-associated steatohepatitis (MASH). Noninvasive tests are very good at determining this, and most people no longer need liver biopsies.
The major treatment for people with MASLD and obesity is weight loss. All people with MASLD should avoid excess alcohol and get the hepatitis A and B vaccines unless they’re already immune. People with MASH who don’t have diabetes are often recommended vitamin E. New drugs, specifically GLP-1 agents such as tirzepatide (Mounjaro), may have beneficial effects. A new medicine, resmetirom (Rezdiffra), is poised to make a dramatic change in the treatment for people with fibrosis.
Because milk thistle is quite safe at recommended doses, I doubt there is any harm in taking it, but I do not recommend it in place of standard treatments.
