and relatively consistent scientific data showing a substantial health benefit.
Contradictory, insufficient, or preliminary studies
suggesting a health benefit or minimal health benefit.
For an herb, supported by traditional use but minimal
or no scientific evidence. For a supplement, little scientific support and/or minimal health
Historical or traditional use (may
or may not be supported by scientific studies)
Medical use of milk thistle can be traced back more than 2,000 years. Nicholas Culpeper,
the well-known 17th-century pharmacist, cited its use for opening “obstructions”
of the liver and spleen and recommended it for the treatment of jaundice.
The dried fruit of milk thistle contain a
flavonoid complex known as silymarin. This constituent is responsible for the medical
benefits of the plant.1 Silymarin is made up of three parts: silibinin, silidianin,
and silicristin. Silibinin is the most active and is largely responsible for the benefits
attributed to silymarin.2
Milk thistle extract may protect the cells of the liver by blocking the entrance of harmful
toxins and helping remove these toxins from the liver cells.34 As with
other bioflavonoids, silymarin is a powerful
antioxidant.5 Silymarin has also been shown to regenerate injured liver
cells.6 Recent studies have shown that silymarin has the ability to block fibrosis,
a process that contributes to the eventual development of cirrhosis in people with inflammatory liver conditions
secondary to diseases such as alcohol abuse or
Milk thistle extract is most commonly recommended to counteract the harmful actions of
alcohol on the liver. Double-blind trials indicate that it helps the liver return to a healthy
state once a person stops drinking.89 Some trials suggest it may
improve quality of life and even life expectancy in people with liver cirrhosis.1011 However, another trial found no effect in cirrhosis patients.12 Milk
thistle alters bile makeup, thereby potentially reducing risk of gallstones.13 However, this needs to be
verified by human clinical trials. Milk thistle extract has been shown to protect the liver
from the potentially damaging effect of drugs used to treat schizophrenia and other forms of
psychosis.14 However, one trial found that it did not protect the liver from the
potentially harmful effects of the drug Cognex (tacrine hydrochloride) used to treat early-stage Alzheimer’s disease. 15
How much is usually taken?
For liver disease and impaired liver function, research suggests the use of 420–600
mg of silymarin per day from an herbal extract of milk thistle standardized to 80% silymarin
content.16 According to research and clinical experience, improvement should be
noted in about eight to twelve weeks. For people with chronic liver disease, milk thistle
extract may be considered a long-term therapy.
For those who prefer, 12–15 grams of milk thistle dried fruits can be ground and
eaten or made into a tea. This should not be considered therapeutic for conditions of the
Are there any side effects or interactions?
Milk thistle extract is virtually devoid of any side effects and may be used by most
people, including pregnant and breast-feeding
women. In fact, it has been recommended as a treatment for itching due to poor gallbladder
function during pregnancy.17 Since silymarin stimulates liver and gallbladder
activity, it may have a mild, transient laxative effect in some people. This will usually
cease within two to three days.
There is one case report of a 57-year-old Australian woman experiencing several episodes of
nausea, abdominal pain, vomiting and weakness after taking a milk thistle
preparation.18 This case is so atypical, however, that the Adverse Drug Reactions
Advisory Committee of Australia questioned whether the product taken might not have contained
other herbs or additives that could be responsible for the adverse reaction.
Are there any drug
Certain medicines may interact with milk thistle. Refer to drug interactions for a list of those medicines.
References (To view, roll mouse over the "References" heading; to hide, click on the heading)
1. Wagner H, Horhammer L, Munster R. The chemistry of silymarin
(silybin), the active principle of the fruits of Silybum marianum (L.) Gaertn.
Arzneim-Forsch Drug Res 1968;18:688–96.
2. Hikino H, Kiso Y, Wagner H, Fiebig M. Antihepatotoxic actions of
flavonolignans from Silybum marianum fruits. Planta Medica
3. Faulstich H, Jahn W, Wieland T. Silibinin inhibition of amatoxin
uptake in the perfused rat liver. Arzneim-Forsch Drug Res 1980;30:452–4.
4. Tuchweber B, Sieck R, Trost W. Prevention by silibinin of phalloidin
induced hepatotoxicity. Toxicol Appl Pharmacol 1979;51:265–75.
5. Feher J, Lang I, Deak G, et al. Free radicals in tissue damage in
liver diseases and therapeutic approach. Tokai J Exp Clin Med
6. Sonnenbichler J, Zetl I. Stimulating influence of a flavonolignan
derivative on proliferation, RNA synthesis and protein synthesis in liver cells. In
Assessment and Management of Hepatobiliary Disease, ed. L Okolicsanyi, G Csomos, G
Crepaldi. Berlin: Springer-Verlag, 1987, 265–72.
7. Schuppan D, Strösser W, Burkard G, Walosek G. Legalon®
lessens fibrosing activity in patients with chronic liver diseases. Zeits
8. Salmi HA, Sama S. Effect of silymarin on chemical, functional and
morphological alterations of the liver. Scand J Gastroenterol
9. Leng-Peschlow E. Alcohol-related liver diseases-use of Legalon®.
Z Klin Med 1994;2:22–7.
10. Ferenci P, Dragosics B, Dittrich H, et al. Randomized controlled
trial of silymarin treatment in patients with cirrhosis of the liver. J Hepatol
11. Velussi M, Cernogoi AM, De Monte A, et al. Long-term (12 months)
treatment with an antioxidant drug (silymarin) is effective on hyperinsulinemia, exogenous
insulin need and malondialdehyde levels in cirrhotic diabetic patients. J Hepatology
12. Pares A, Plancs R, Torres M, et al. Effects of silymarin in alcoholic
patients with cirrhosis of the liver: results of a controlled, double-blind, randomized and
multicenter trial. J Hepatol 1998;28:615–21.
13. Nassuato G, Iemmolo RM, Strazzabosco M, et al. Effect of silibinin on
biliary lipid composition. Experimental and clinical study. J Hepatol
14. Palasciano G, Portinascasa P, Palmieri V, et al. The effect of
silymarin on plasma levels of malondialdehyde in patients receiving long-term treatment with
psychotropic drugs. Curr Ther Res 1994;S5:S37–45.
15. Allain H, Schück S, Lebreton S, et al. Aminotransferase levels
and silymarin in de novo tacrine-treated patients with Alzheimer’s disease. Dementia
Geriatr Cogn Disorders 1999;10:181–5.
16. Brown DJ. Herbal Prescriptions for Better Health. Rocklin,
CA: Prima Publishing, 1996, 151–8.
17. Reyes H. The spectrum of liver and gastrointestinal disease seen in
cholestasis of pregnancy. Gastroert Clin N Am 1992;21:905–21.
18. Adverse Drug Reactions Advisory Committee. An adverse reaction to the
herbal medication milk thistle (Silybum marianum). MJA
The information presented in Aisle7 is for informational purposes only.
It is based on scientific studies (human, animal, or in vitro), clinical experience,
or traditional usage as cited in each article. The results reported may not necessarily occur
in all individuals. For many of the conditions discussed, treatment with prescription or over
the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist
for any health problem and before using any supplements or before making any changes in