Milk Thistle

Also called

Mary Thistle, Holy Thistle, Marian Thistle, Our Lady's Thistle, St. Mary Thistle, Wild Artichoke

Older scientific names

Carduus marianus

Traditional use

These are traditional uses, not proven treatments.

• Milk thistle has historically been used for liver problems and to increase breast milk.[1]

• Based on long-standing use, the European Medicines Agency recognizes milk thistle fruit as a traditional herbal medicine for adults. It can be used to relieve indigestion and a feeling of fullness, and to support liver function after a doctor has ruled out serious conditions. This rests on at least 30 years of safe use, not on proof from clinical trials.[3]

• Milk thistle has been used for more than 2,000 years, mainly for the liver:

  • The ancient Greek physician Dioscorides recommended it for snake bites
  • The Roman writer Pliny the Elder said the plant's juice mixed with honey helped carry off bile
  • In the Middle Ages it was valued as an antidote to substances that poison the liver
  • American Indian or Alaska Native people use it for boils and other skin problems

  The leaves have also been eaten in salads, and the roasted fruit used as a coffee substitute.[2]

Laboratory & animal research

Lab and animal results show what might be worth studying in people. They don't show that the herb has these effects in humans.

• In lab and animal studies, silymarin (the main active mix in milk thistle) protected liver cells from toxic chemicals and helped the liver regrow. It also slowed the growth of some cancer cells, including prostate, breast, colon and skin cancer cells, and in some tests made certain chemotherapy drugs work better. None of these findings have been repeated in human trials.[2]

  Technical detail: silybin potentiated cisplatin and doxorubicin in ovarian (A2780) and breast (MCF-7) cancer cells and etoposide in LN229 glioma cells; animal models included tongue, skin, bladder, colon and small-intestine tumors.

Research in people

• The European Medicines Agency reviewed several studies in people with liver problems. They suggested milk thistle may improve liver function and symptoms. No firm conclusions could be drawn, because the studies were poorly designed, small, and used different doses and lengths of treatment.[3]

• A 2007 Cochrane review looked at 18 trials with 1,088 people with alcohol-related liver disease or hepatitis B or C. Compared with placebo or no treatment, milk thistle didn't significantly reduce deaths, liver complications or liver damage seen in biopsies. Fewer people died of liver causes when all trials were combined, but not in the better-quality trials. Most trials were of low quality, and the reviewers concluded that the benefits of milk thistle are questionable.[4]

  Technical detail: all-cause mortality RR 0.78 (95% CI 0.53 to 1.15); complications RR 0.95 (0.83 to 1.09); liver-related mortality RR 0.50 (0.29 to 0.88) in all trials, RR 0.57 (0.28 to 1.19) in high-quality trials; adverse events RR 0.83 (0.46 to 1.50).

• Trials of milk thistle for alcohol-related liver disease, hepatitis B and C, non-alcoholic fatty liver disease and liver damage from chemotherapy have had conflicting or too limited results. Two NIH-funded studies, one in hepatitis C and one in a more serious form of fatty liver disease (NASH), found no benefit from the milk thistle extract silymarin.[1]

• Research suggests milk thistle extracts may help control blood sugar in people with type 2 diabetes. Most of these studies were done in Middle Eastern countries, so it's unclear whether the results apply to other people. It's also unclear whether milk thistle affects breast milk production.[1]

• The US National Cancer Institute says there's too little human research to recommend milk thistle for people with cancer outside of well-designed clinical trials. Small studies have found:

  • Children with leukemia whose chemotherapy was harming their liver: 50 children took silymarin or a dummy pill for 4 weeks, and the silymarin group had better results on one liver blood test
  • Head and neck cancer: in 30 people, silymarin lowered and delayed mouth sores caused by radiation
  • Breast cancer: in 101 women having radiation, a silymarin cream delayed skin damage and fewer women had moderate or severe skin reactions than with the usual cream
  • Advanced liver cancer: all 3 people in a small safety study died within 23 to 69 days, likely from liver failure, though the study product couldn't be ruled out

  In Europe, a form of silymarin is given into a vein as an antidote to death cap mushroom poisoning.[2]

  Technical detail: acute lymphoblastic leukemia trial, AST significantly lower (P = .05), trend for ALT (P = .07); breast trial (Leviaderm vs panthenol cream), median time to skin toxicity 45 vs 29 days, grade 2 toxicity in week 5 9.8% vs 52%; hepatocellular carcinoma phase I study of silybin phosphatidylcholine 2 g/day; Amanita phalloides antidote is intravenous silybin.