Health Benefits of Milk Thistle

Milk thistle is a plant that is known for its anti-inflammatory and antioxidant properties. It has been used for hundreds of years to treat illnesses like liver disease and metabolic disorders. 

Milk thistle’s botanical name is Silybum marianum, and the plant is also commonly referred to as Mary thistle, holy thistle, Marian thistle, wild artichoke, Our Lady’s thistle, and St. Mary’s Thistle. It is native to Europe and also found in South and North America.

While herbalists have touted the health benefits of milk thistle for centuries, it’s only in modern times that researchers have begun to understand its health benefits. Most existing studies focus on silymarin, the active ingredient in milk thistle, which is rich in flavonolignans. However, the data is mixed when it comes to milk thistle’s benefits.

 Here are the potential health benefits of milk thistle. 

Dietary supplements are minimally regulated by the FDA and may or may not be suitable for you. The effects of supplements vary from person to person and depend on many variables, including type, dosage, frequency of use, and interactions with current medications. Please speak with your healthcare provider or pharmacist before starting any supplements.

The milk thistle flower at sunset

By Eve Livesey / Getty Images

It May Help Treat Liver Diseases

Milk thistle is most well known for its healing and protective liver benefits. But so far, the research is mixed, and at times been criticized for being poorly conducted. According to the National Library of Medicine, the most convincing data is that milk thistle shows promise in treating nonalcoholic fatty liver disease (NAFLD), a condition that affects 20-30% of adults. A 2017 review found that supplementing with milk thistle lowers liver enzyme levels in people with liver disease. However, more studies are needed to determine the clinical relevance of lowering liver enzyme levels.

It Could Reduce Inflammation

Chronic inflammation is a factor in many diseases and conditions, including diabetes, heart disease, allergies, and arthritis. A 2015 study found that supplementing with milk thistle may help suppress inflammation in your cells. There are also indications that milk thistle helps regulate cytokines, which are responsible for the body’s inflammatory response.

It Can Act As An Antioxidant

Milk thistle may have potent antioxidant qualities. A 2020 review found that milk thistle is a multifunctional compound capable of treating a variety of different conditions. The study researchers hypothesize that milk thistle’s antioxidant qualities make it a good candidate for treating conditions like cancer, hepatitis, NAFLD, diabetes, depression, and heart disease.

Milk Thistle May Help With Metabolic Syndrome

There is some evidence that milk thistle can help with metabolic syndrome, a group of conditions that increase your risk of heart disease, diabetes, and stroke.

Research has found that milk thistle extract (silymarin) has exhibited the ability to decrease blood glucose levels, hemoglobin A1C (a blood protein linked to sugar), total cholesterol, triglycerides (a type of fat in your blood), and LDL (low-density protein)—all of which can protect against the effects of metabolic syndrome.

Some data also indicates that milk thistle lowers insulin resistance and decreases fasting insulin levels, which has implications for diabetes.

It Could Boost Cancer Treatments and Slow Cancer Growth

Milk thistle may strengthen the efficacy of cancer drugs that treat ovarian and breast cancer. Milk thistle also may help slow cancer cell growth in conditions like prostate, breast, and cervical cancer. However, more research is needed to determine if milk thistle can help treat or prevent cancer. Currently, not much is known about how milk thistle may interact with radiation therapy and other cancer treatments.

It Helps Treat Mushroom Poisoning

Milk thistle has been used to treat cases of mushroom poisoning for years. Milk thistle is thought to be the only antidote to a mushroom toxin (Amanita phalloides) that can cause severe liver failure and death. In Europe, milk thistle is given intravenously to treat this condition.

How to Take Milk Thistle

As a supplement, milk thistle is usually given in capsule or pill form. The seeds of the milk thistle plant contain its active ingredients and supplements are formed using extracts from these seeds. You can also eat milk thistle leaves as part of a salad, for example. The flower’s fruits are even roasted at times and used in place of coffee. In Europe, milk thistle is given by IV as an antidote to mushroom poisoning (Amanita phalloide).


There are no specific recommended dosages for milk thistle. A 2019 review found that milk thistle was safe and well tolerated at daily doses up to 700 mg, three times a day, for up to 24 weeks. However, some reported side effects were nausea and diarrhea.

You should speak to your healthcare provider for advice about how much milk thistle to take. Talk to them about what other medications you are currently taking to determine whether taking milk thistle is right for you.

Is Milk Thistle Safe?

Milk thistle is thought to be safe, even in relatively high dosages. However, some people may experience allergic reactions to milk thistle, especially if they are allergic to other plants or flowers in the same family as milk thistle, such as daisy, ragweed, marigold, or chrysanthemum. Because milk thistle has the potential to lower blood sugar, people with type 2 diabetes should speak to their healthcare provider before taking milk thistle. Milk thistle hasn’t been studied in people who are pregnant or breastfeeding, so caution is advised.

Potential Drug Interactions

According to the National Library of Medicine, there are no known medications or substances that shouldn’t be taken with milk thistle. But that doesn’t mean that interactions don’t exist. That’s why you should always talk to your healthcare provider before taking a supplement.

What to Look For

Herbal supplements like milk thistle are not regulated or approved by the FDA. For this reason, ingredients in capsules and tablets may vary, and it’s smart to exercise caution when purchasing milk thistle. A 2013 study found that whole milk thistle and whole seeds are more likely to be contaminated with fungus than capsules, liquid extracts, or tea bags.

Always talk to your healthcare provider before taking a supplement, and consider purchasing a supplement that has been third-party tested, such as by ConsumerLab or NSF International.

Can You Take Too Much Milk Thistle?

Milk thistle has been found to be safe at fairly high doses, taken multiple times a day, and for several weeks at a time. However, allergic reactions are more likely to be seen at higher doses, such as 1,500 mg/day. Unpleasant side effects, such as diarrhea, are also more likely with higher doses.

Side Effects of Milk Thistle

There haven’t been serious side effects of taking milk thistle reported . The most common side effects are usually gastrointestinal in nature and may include diarrhea, heartburn, and gastroenteritis. Some people also experience headaches and skin reactions, like hives or a rash.

A Quick Review

Milk thistle is an herbal supplement that’s considered safe and generally well tolerated by most people. More research is needed regarding its medicinal benefits, but it’s thought to have anti-inflammatory qualities that can help with conditions such as liver disease, diabetes, and even cancer. Because milk thistle is not regulated by the FDA, and it’s unknown whether it interacts with other substances or medications, you should connect with your healthcare provider before taking milk thistle.

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