Health Benefits of Milk Thistle

Medically Reviewed by Dany Paul Baby, MD on November 30, 2022
3 min read

Herbalists and some doctors have used milk thistle, also known as Mary thistle and holy thistle, for hundreds of years to treat liver and gallbladder problems. Milk thistle has also been used to protect the liver against environmental toxins. Some of the conditions treated by milk thistle include:

  • Hepatitis (a disease affecting your liver)
  • Cirrhosis (scar tissue replaces your healthy liver cells)
  • Jaundice (skin and the whites of your eyes turn yellow)
  • bile-duct function (inhibited ability to carry bile duct from the liver to the gallbladder)

Milk thistle seeds contain a group of bioflavonoids known as silymarin. It is believed that silybin is the most active compound in this group and that it can prevent toxins from causing damage to your liver.

It has also been suggested that milk thistle may decrease the side effects of cancer treatment. However, clinical studies have not proven any of these claims. Milk thistle and its derivatives have not been approved by the U.S. Food and Drug Administration as a treatment for any medical condition.

Milk thistle is native to Mediterranean countries but is classified as a weed in the United States. Washington state classifies it as a noxious weed because milk thistle is considered a threat to vegetation and can harm animals that eat it. The state has regulations against growing or distributing it for purposes of cultivation and harvest.

The primary active ingredients in milk thistle are a group of compounds called silymarin, and they are all types of flavonoids — natural substances that are found in vegetables, grains, fruits, and even the barks, stems, and seeds of plants. They are well-known to have a wide variety of health benefits and for their ability to fight disease.

Silymarin includes substances known as flavonolignans, which are a group of flavonoids recognized for their ability to protect the liver from toxins and diseases.

Milk thistle offers the following health benefits:

Disease Prevention

As an antioxidant — a substance that helps protect your cells from damage and may prevent heart disease and cancer — milk thistle is able to protect the liver from free radicals, including those that come from toxins such as ethanol, acetaminophen, and even carbon tetrachloride, a chemical that can damage your organs and central nervous system.

The key ingredients in milk thistle protect cell membranes from free-radical damage and can remove free radicals from within the cells. Milk thistle is also an anti-inflammatory compound. It regulates cytokines, helping to reduce inflammation. Reduced inflammation can help prevent the development of serious diseases.

Diabetes Management

Some studies have shown that milk thistle, taken along with regular treatment, can reduce blood sugar and cholesterol levels in people who have type 2 diabetes, but more research is needed.

Other Benefits

Milk thistle has been used as a dietary supplement to help with the following:

  • Mushroom poisoning
  • Viral hepatitis
  • Cirrhosis
  • Alcoholic liver disease
  • Carbon tetrachloride poisoning

Milk thistle is usually consumed as a supplement or as an ingredient added to a tea mixture. It can also be combined with other herbs. It’s rich in antioxidants which can help prevent the formation of serious diseases such as cancer.

Nutrients per Serving

One tea bag that contains milk thistle as an ingredient contains:

  • Calories: 0
  • Protein: 0 grams
  • Fat: 0 grams
  • Carbohydrates: 0 grams
  • Fiber: 0 grams
  • Sugar: 0 grams

Portion Sizes

Some people have reported mild gastrointestinal problems when taking milk thistle, including nausea, heartburn, and upset stomach.

You could also have an allergic reaction to milk thistle, especially if you’re allergic to related plants such as ragweed, chrysanthemums, marigolds, or daisies.

Milk thistle is primarily taken in supplements — sold as tablets, capsules, or extract — primarily to help with liver function. The nutritional content varies for each brand, so be sure to read the label. No optimal dose has been defined, so check with your health care provider before taking milk thistle supplements.

Milk thistle is also available as a tea, but the tea is believed to have minimal medicinal value, so it may not provide the same health benefits as supplements.

If you choose to have milk thistle as a tea, it’ll probably be mixed with other herbs or added to a tea. To prepare the tea, simply steep a teabag containing milk thistle in hot water for three to five minutes.