Milk Thistle

This fact sheet provides basic information about milk thistle—common names, what the science says, potential side effects and cautions, and resources for more information.

Milk thistle is a flowering herb native to the Mediterranean region. It has been used for thousands of years as a remedy for a variety of ailments, and historically was thought to have protective effects on the liver and improve its function. Today, its primary folk uses include liver disorders such as cirrhosis and chronic hepatitis, and gallbladder disorders. Other folk uses include lowering cholesterol levels, reducing insulin resistance in people who have both type 2 diabetes and cirrhosis, and reducing the growth of breast, cervical, and prostate cancer cells.

Silymarin, which can be extracted from the seeds (fruit) of the milk thistle plant, is believed to be the biologically active part of the herb. The seeds are used to prepare capsules, extracts, powders, and tinctures.

Latin Name–Silybum marianum

information from NCCAM verbatim

• Milk thistle (Silybum marianus) is regarded as one of the most important herbal liver tonics and restoratives. As is the case with Feverfew, medical use of Milk thistle may be traced back more than 2,000 years. Like Feverfew, Milk thistle has been subject to many clinical trials which clearly demonstrate its effectiveness. It is frequently recommended to counteract the harmful effects of alcohol and other drugs on the liver and clinical studies have shown that it helps the liver to return to normal functioning once drinking has stopped. Scientific analysis of Milk thistle shows that it contains a flavonoid complex called silymarin, which is largely responsible for the medical benefits of this herb. Silymarin is a powerful anti-oxidant and can block the entrance of toxins into the liver and remove toxins at a cellular level, thereby resulting in regeneration of liver cells and improved liver functioning. This would have a direct impact on overall systemic health as the liver is one of the most important organs in the body.

What Milk thistle Is Used For

• Milk thistle is believed to have protective effects on the liver and improve its function. It is typically used as an herbal remedy to treat liver cirrhosis, chronic hepatitis (liver inflammation), and gallbladder disorders.
• Treatment claims also include:
  • Lowering cholesterol levels
  • Reducing insulin resistance in people with type 2 diabetes who also have cirrhosis
  • Reducing the growth of cancer cells in breast, cervical, and prostate cancers

Herbal Remedy Products with Milk thistle as part of the ingredients

MiGone Plus™ – Natural herbal remedy to relieve all types of headaches including migraines and ocular migraines, plus reduce anxiety and muscle tension Prevents migraines and chronic headaches Stops tension headaches before they start Reduces muscle tension and spasms Relieves the symptoms of arthritis Relaxes and reduces anxiety and tension

How Milk thistle Is Used

Milk thistle is a flowering herb. Silymarin, which can be extracted from the seeds (fruit), is believed to be the biologically active part of the herb. The seeds are used to prepare capsules containing powdered herb or seed; extracts; and infusions (strong teas).

What the Science Says about Milk thistle

• There have been some studies of milk thistle on liver disease in humans, but these have been small. Some promising data have been reported, but study results at this time are mixed.
• Although some studies conducted outside the United States support claims of oral milk thistle to improve liver function, there have been flaws in study design and reporting. To date, there is no conclusive evidence to prove its claimed uses.
• NCCAM is supporting a phase II research study to better understand the use of milk thistle for chronic hepatitis C. With the National Institute of Diabetes and Digestive and Kidney Diseases, NCCAM is planning further studies of milk thistle for chronic hepatitis C and nonalcoholic steatohepatitis (liver disease that occurs in people who drink little or no alcohol).
• The National Cancer Institute and the National Institute of Nursing Research are also studying milk thistle, for cancer prevention and to treat complications in HIV patients.

Previous laboratory studies suggested that milk thistle may benefit the liver by protecting and promoting the growth of liver cells, fighting oxidation (a chemical process that can damage cells), and inhibiting inflammation. However, results from small clinical trials of milk thistle for liver diseases have been mixed, and two rigorously designed studies found no benefit.

A 2012 clinical trial, cofunded by NCCAM and the National Institute of Diabetes and Digestive and Kidney Diseases, showed that two higher-than-usual doses of silymarin were no better than placebo for chronic hepatitis C in people who had not responded to standard antiviral treatment.

The 2008 Hepatitis C Antiviral Long-Term Treatment Against Cirrhosis (HALT-C) study, sponsored by the National Institutes of Health (NIH), found that hepatitis C patients who used silymarin had fewer and milder symptoms of liver disease and somewhat better quality of life but no change in virus activity or liver inflammation.

Side Effects and Cautions of Milk thistle

• In clinical trials, milk thistle generally has few side effects. Occasionally, people report a laxative effect, upset stomach, diarrhea, and bloating.
• Milk thistle can produce allergic reactions, which tend to be more common among people who are allergic to plants in the same family (for example, ragweed, chrysanthemum, marigold, and daisy).
• It is important to inform your health care providers about any herb or dietary supplement you are using, including milk thistle. This helps to ensure safe and coordinated care.