Milk thistle is a plant many outdoor enthusiasts are familiar with. The vibrant purple petals and the prickly hairs are present along many hiking trails. The plant — known by the botanical name Silybum marianum — is native to the Mediterranean, Europe, the Americas, and Australia. It’s commonly called Mary thistle, holy thistle, and Scotch thistle.
What many people don’t know is that the plant may be beneficial to human health. Milk thistle contains an active ingredient known as silymarin — which is often sold as milk thistle extract. This compound has been linked to the potential treatment of liver conditions and other disorders.
Many alternative medicine practitioners add the plant to their diets or simply opt for a milk thistle supplement. Here, we’ll delve deeper into the benefits of milk thistle backed by scientific research.
Health Benefits of Milk Thistle
1. Liver Health
Milk thistle extract is most commonly taken for treating or preventing liver disease and promoting overall liver function. According to The National Center for Complementary and Integrative Health (NIH), silymarin extract is the most commonly used herbal supplement in the U.S. (1).
A study published in Phytotherapy Research found that silymarin has been used to treat hepatitis C, alcoholic liver disease, toxin-induced liver diseases, and iron toxicity. Researchers found that silymarin works as an antioxidant to reduce free radicals and prevents toxins from binding to healthy cell membranes (2).
A small study published in the Journal of Emergency Medicine examined the effects of milk thistle extract on two individuals who ingested poisonous mushrooms. The researchers found that treatment with silibinin — a form of silymarin — helped to delay the onset of symptoms and prevented toxicity.
Additional research published in the European Journal of Medical Chemistry examined the effects of milk thistle extract on cancer cells and liver cells. Researchers found that people who took silymarin had significant reductions in liver problems. Researchers believe that the antioxidant properties of milk thistle help to prevent oxidative damage and reduce inflammation (3).
Most research shows that supplementing a healthy lifestyle with milk thistle may help to control liver disorders and reduce liver damage. Clinical studies have not been conclusive and more research is needed to establish the exact mechanisms behind milk thistle liver benefits.
2. Bone Health
Small laboratory studies show that milk thistle may offer protective benefits for bones. A study published in Biomed Research international examined the impacts of silymarin on bone diseases. Researchers found that taking a milk thistle supplement in preclinical testing resulted in a decrease in bone loss caused by estrogen deficiency (4).
A second animal study investigated the impacts of silymarin on rats. Researchers found that silymarin helped to improve calcium, phosphorus and osteocalcin levels that indicate the formation of stronger bones (5).
3. Decreases Inflammation
Milk thistle extract contains powerful antioxidant compounds that are beneficial for overall human health. Antioxidants help to target free radicals — compounds that cause cell processes to deteriorate. Free radical damage has been linked to serious diseases including a decrease in brain function as well as premature aging.
Antioxidants also help to reduce inflammation that can cause oxidative stress. By reducing inflammation, milk thistle may help to reduce joint pain and improve blood circulation. The anti-inflammatory properties of milk thistle are still emerging but may be beneficial for a host of ailments.
4. Brain Health
Research shows that silymarin offers neuroprotective effects that can help decrease inflammation and oxidative stress that lead to neurological conditions such as Alzheimer’s disease and Parkinson’s disease (6).
An animal study published in Oxidative Medicine and Cellular Longevity examined the impacts of milk thistle extract of neurodegenerative diseases. Researchers found that silymarin and other polyphenols may help to reduce plaque build-up that can affect cognition (7).
Much of the research includes cautions regarding the bioavailability of silymarin. The compound is easily absorbed in the intestine, meaning it bypasses absorption into the bloodstream. For many of these benefits to occur, silymarin needs to be combined with other compounds that improve its bioavailability (8).
5. Cancer Uses
Milk thistle extract is commonly used in alternative medicine as a way to supplement traditional cancer treatments. Modern medical research in the arena is scarce and has often produced conflicting results. There are no human clinical trials regarding the efficacy of using milk thistle as part of cancer treatment. There are however a few small animal studies that demonstrate interesting results.
One such animal study published in Biomed Research international found that flavonoids in milk thistle may offer chemoprotective effects (9). Additional animal models showed promise in regards to reduced tumor growth in pancreatic cancer and breast cancer (10).
6. Blood Sugar Benefits
Taking milk thistle extract may be particularly beneficial for people who suffer from Type 2 diabetes. A study published in the review of Diabetic Studies examined the use of milk thistle in diabetes treatment. Researchers found that silymarin contains compounds that may help lower blood sugar levels and decrease insulin resistance (11).
The kidney and liver health benefits of silymarin may also be useful for people with diabetes who suffer from complications. Milk thistle may also help lower high cholesterol levels, improving heart health and preventing additional complications (12).
Side Effects of Milk Thistle
As with any natural medicine, supplements, or holistic alternatives, it’s important to seek medical advice from a healthcare professional before starting use. Your healthcare provider can help you understand side effects and evaluate its use for your specific needs.
Milk thistle may cause allergic reactions in people who are allergic to the plant as well as other plants in the Asteraceae family. Avoid milk thistle seed, extracts, and teas if you suffer from related allergies.
The United States Food and Drug Administration (FDA) does not regulate supplements. If you choose to use milk thistle supplements, look for ones from a reputable brand. Also opt for varieties that don’t contain added ingredients, which may affect the efficacy of silymarin.
Milk thistle may also cause stomach upset for certain individuals. Symptoms include indigestion, diarrhea, gas, and bloating. Stop use immediately if you experience these side effects.
Milk Thistle Recap
Milk thistle is widely used as a supplemental treatment for liver problems. It may also offer benefits in terms of reducing inflammation and preventing cellular damage caused by free radicals. Remember that research on milk thistle is still in the early stages and you should consult your physician before using this herb to treat any medical conditions.