Laboratory and animal studies report that milk thistles have some anticancer capabilities.
Several small studies suggested that silymarin (the active ingredient of milk thistle) has the following benefits against cancer:
- Stimulates enzymes that limit how toxins affect the body
- Decreases the side effects of chemotherapy on the liver without harming the cancer treatment
- Improves quality of life
- Lowers cholesterol after undergoing surgery for prostate cancer
- Reduces radiation-related mucositis
- Reduces skin rashes caused by radiation therapy and surgery in women with breast cancer
- Enhances the efficacy of cisplatin and doxorubicin against ovarian and breast cancer cells
However, research is still in its initial stages, and further human trials are necessary to confirm its effectiveness.
What is Milk Thistle?
Milk thistle is a flowering plant, native to the Mediterranean region, that has been used for 2000 years as an herbal remedy. It belongs to the daisy and ragweed family.
Silymarin, found in milk thistle seeds, is a mixture of compounds:
- Silybin
- Isosilybin
- Silychristin
- Isosilychristin
- Silydianin
- Taxifolin
Other names for milk thistle include:
- Holy thistle
- Marian thistle
- Mary thistle
- St. Mary thistle
- Our Lady's thistle
- Wild artichoke
- Mariendistel (German)
- Chardon-Marie (French)
What Are the Uses of Milk Thistle?
Milk thistle is commonly used as a natural treatment for:
Due to the high antioxidant properties of silymarin, milk thistle may protect the liver and its cells.
Although there is insufficient evidence, milk thistle has been used for a few conditions that affect the following organs:
- Pancreas
- Bile duct
- Kidneys
- Myocardium
- Central nervous system
It may help lower insulin resistance and has gained a reputation as an antidiabetic. However, the results from various studies report mixed reviews. More studies should be conducted to understand the potential benefit of milk thistle as an antidiabetic agent.
Is Milk Thistle Approved by the FDA for Use as a Cancer Treatment?
The U.S. FDA does not approve the use of milk thistles for cancer treatment. It is sold as a dietary supplement in the United States. Dietary supplements are products meant to be added to your diet and not used instead of drugs to treat, prevent or cure diseases.
It is the manufacturing and production company's responsibility to ensure that the dietary supplements are safe and that no false or misleading claims are made on the label. The FDA does not regulate dietary supplements.
What Are the Risks and Concerns Associated With Milk Thistle?
Milk thistle can trigger an allergic reaction in some people.
Some of the contraindications associated with milk thistle consumption include:
- Allergic to artichokes, kiwi, ragweed, daisies, marigolds, and chrysanthemums
- Diabetes
- Endometriosis
- Pregnant and breastfeeding individuals
- Children
Milk thistle can interact with various drugs, including:
- Antibiotics
- Statins
- Antihypertensives
Milk thistle can lower blood sugar. People with diabetes should consult their doctor before taking milk thistle.
From 
Milk Thistle: Benefits and Side Effects. https://www.webmd.com/digestive-disorders/milk-thistle-benefits-and-side-effects
Milk Thistle (PDQ®)–Patient Version. https://www.cancer.gov/about-cancer/treatment/cam/patient/milk-thistle-pdq
Milk Thistle. https://www.oncolink.org/healthcare-professionals/nci/pqid-cdr00003470082