WARNING!
This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.
Milk thistle is an herb that’s been used for thousands of years to support liver, kidney and gallbladder health.1 It contains the flavonoid silymarin, which is thought to be responsible for many of its beneficial effects, including liver protection and antioxidant, antiviral and anti-inflammatory properties.
Native to the Mediterranean but now found throughout the world, milk thistle is regarded as a weed in some areas, despite its therapeutic potential. When the leaves are crushed they release a milky sap, giving this herb its characteristic name.2
Silymarin, its active component, is actually a group of compounds (silibinin, silidianin and silicristin), which work together to provide multiple health benefits. How does silymarin protect your liver? For starters, it’s an antifibrotic, which means it helps prevent tissue scarring, and it’s thought to act as a “toxin blockade agent” by inhibiting the binding of toxins to liver cell membrane receptors.3
Not only is silymarin used to treat alcoholic liver disease, acute and chronic viral hepatitis and toxin-induced liver diseases, but this powerful compound has been shown in animal studies to reduce liver injury caused by a number of drugs and environmental toxins, including:4
- Amanita phalloides (the poisonous "death cap" mushroom)
- Acetaminophen (Tylenol)
- Phenylhydrazine (a poisonous liquid)
- Radiation
- Iron overload
- Carbon tetrachloride (a probable carcinogen common in building materials and cleaning agents)
- Alcohol
- Psychotropic medications
- Chemotherapy
Milk Thistle Suppresses Cellular Inflammation Using a Two-Phase Process
Milk thistle’s anti-inflammatory effects are among its greatest achievements, and recent research suggest this is accomplished, in part using a two-phase process similar to those used by other beneficial natural compounds like curcumin (found in turmeric) and EGCG (epigallocatechin gallate, a component of green tea).5
The study revealed the first-phase cellular response to silymarin in cells is a rapid increase in expression of genes associated with cellular stress, specifically endoplasmic reticulum (ER) stress. In severe cases, such stress may lead to cell death, which can actually be beneficial in some cases (such as cancer).
The second phase involves a longer suppression of gene expression associated with inflammation. Along with inhibiting inflammatory signaling pathways, silymarin also:6
• Activates AMP-activated protein kinase (AMPK) — AMPK is an enzyme inside your body’s cells. It’s sometimes called a “metabolic master switch” because it plays an important role in regulating metabolism.7 According to the Natural Medicine Journal:8
“AMPK induces a cascade of events within cells that are all involved in maintaining energy homeostasis … AMPK regulates an array of biological activities that normalize lipid, glucose, and energy imbalances. Metabolic syndrome (MetS) occurs when these AMPK-regulated pathways are turned off, triggering a syndrome that includes hyperglycemia, diabetes, lipid abnormalities and energy imbalances.
… AMPK helps coordinate the response to these stressors, shifting energy toward cellular repair, maintenance, or a return to homeostasis and improved likelihood of survival. The hormones leptin and adiponectin activate AMPK. In other words, activating AMPK can produce the same benefits as exercise, dieting, and weight loss — the lifestyle modifications considered beneficial for a range of maladies.”
• Inhibits mammalian target of rapamycin (mTOR) — This is likely beneficial, as when the mTOR pathway is activated it may increase your risk of cancer. This pathway is ancient, but relatively recently appreciated and has only been known for less than 20 years.
Odds are very high your doctor was never taught this in medical school and isn't even aware of it. Many new cancer drugs are actually being targeted to use this pathway. Drugs using this pathway have also been given to animals to radically extend their lifespan.
Beyond Your Liver: What Else Is Milk Thistle Good For?
Milk thistle contains silymarin and silybin, antioxidants that are known to help protect the liver from toxins, including the effects of alcohol. Not only has silymarin been found to increase glutathione (a powerful antioxidant that is crucial for liver detoxification), but it also may help to regenerate liver cells.9
However, to regard milk thistle as solely an herb for liver health would be doing it a disservice, as it has many additional benefits. Among them are potential anticancer effects.10 As reported by the American Botanical Council (ABC):11
“A number of studies, both in vitro and in vivo, suggest that milk thistle is potentially beneficial in treating or preventing various cancers: inhibiting prostate cancer cells and increasing apoptosis (programmed cell death) in them; inhibiting growth and stimulating regression of skin tumors with topical application;
… [I]nhibiting induction of tongue squamous-cell cancer; decreasing incidences of bladder neoplasms; inhibiting growth and DNA synthesis in breast and cervical cancer cells; reducing frequency of drug-induced colon adenocarcinomas, and inhibiting proliferation in leukemia cells.
Silybin may be useful in hormone-refractory human prostate cancer and may enhance the efficacy of tumor necrosis factor (TNF)-alpha-based chemotherapy. Indeed, its liver protectant effects in chemo- and radiation therapies may be as valuable to cancer patients as milk thistle's antineoplastic effects, especially in drug-resistant cancers.
… Patients with metastasizing brain tumors who received milk thistle and omega-3 fatty acids before radiation had improved survival times and fewer side effects. The authors suggest, based on a number of pharmacological studies, that topical silymarin would be a beneficial addition to sunscreens in protecting against ultraviolet-B-induced skin cancers.
They recommend that practitioners include standardized milk thistle products in cancer treatment regimens, especially where there is damage or potential damage to liver or kidneys from allopathic treatment.”
4 More Potential Health Benefits of Milk Thistle
Aside from liver health and cancer protection, milk thistle also shows promise for:12
• Kidney health — Milk thistle’s effects on your kidneys has been said to “closely mirror the herb's effects on the liver.” It shows promise for stimulating cell regeneration in the kidneys and may prove useful even in patients on dialysis.
• Heart health — Milk thistle appears to raise levels of beneficial HDL cholesterol and decrease the risk of atherosclerosis. Silymarin may also help reduce blood pressure.
• Diabetes — Among people with diabetes, those who took silymarin for four months experienced improvements in their glycemic profile, including a significant decrease in glycosylated hemoglobin (HbA1c — a measure of blood sugar average over the last three months), fasting blood glucose, total cholesterol, LDL cholesterol and triglycerides compared to those taking a placebo.13 Milk thistle may also improve blood sugar control in people with diabetes.14
• Brain health — Milk thistle appears to have neuroprotective properties and there is early research suggesting it may be beneficial for multiple sclerosis and Parkinson’s disease. Animal studies also suggest that silymarin may suppress the formation of amyloid beta-protein (a toxic protein linked to Alzheimer’s), thereby helping reduce the risk of Alzheimer’s disease.15
Adding to its allure, milk thistle appears to be safe and well tolerated in most people with few side effects. ABC reported:16
In general, milk thistle has been recognized as a safe and well-tolerated herb with a limited adverse event profile similar to placebo. Although no short-term trials of high silymarin intake have been done in healthy populations, it seems clear that under the restricted conditions of available trials, milk thistle appears to be quite safe … an oral form standardized to contain 70 to 80 percent silymarin given at a dosage of 420 mg daily, was safe for up to 41 months of use, and significant drug reactions were not reported.
The majority of reported adverse events are unrelated to the product, or difficult to separate from the concomitant disease. Adverse effects associated with oral ingestion of milk thistle are rare and include gastrointestinal problems … At doses greater than 1.5 g per day, a laxative effect is possible due to increased bile secretion and flow. Mild non-serious allergic reactions have also been noted.”
If you have concerns about your liver or kidney health, or are interested in any of the potential anticancer, antidiabetes and heart-boosting properties of silymarin, a high-quality milk thistle supplement may be worth considering. On a dietary level, you can also find silymarin in artichokes, turmeric and coriander (cilantro), although milk thistle is the richest known source.
Considerations Before Growing Milk Thistle at Home
Before you think about planting milk thistle in your garden, though, be forewarned: It is a highly invasive weed that can spread quickly not just all over your yard, but to the neighboring lawns as well. Milk thistle is also toxic to livestock, so if you have animals roaming around your yard, you should refrain from planting it outdoors.
Milk thistle can grow in any soil type, even in poor-quality soil. Plant the seeds at least a quarter-inch deep, just after the last frost. Ideally place them in an area that gets full sun. Once you notice the flowers starting to dry, and a white pappus turf (similar to a dandelion) forms, they’re ready for harvest.17
How to Store Milk Thistle
It’s best to place the flower heads in a paper bag and then keep in a dry place. This will allow the drying process to continue. Once you’re certain that they’re dried, give the bag a few whacks to separate the seeds from the flower heads.18 Milk thistle seeds are best placed in a dry, airtight container. Only take them out when you’re ready to use them.19
Milk Thistle Recipes: Here’s How to Add It to Your Diet
There are numerous ways to incorporate milk thistle into your foods. The powdered seeds can be sprinkled on salads or added to smoothies and vegetable juices. You can also add the stalks, flowers, leaves and roots to salads, raw dishes and other cooked meals.20 Milk thistle can also be made into tea. Some health food stores sell ready-to-use milk thistle tea, but you can make your own using the seeds. Here’s a recipe you can try:
Milk Thistle Tea
Ingredients:
Procedure:
Crush the seeds and leaves and place in a muslin bag. Let the bag steep in hot water for five minutes. Add a teaspoon of raw honey for flavor.
Milk Thistle Oil
In addition to oral milk thistle supplements, you can also purchase it in essential oil form. Extracted from the ripe seeds, milk thistle oil is abundant in sterols, essential fatty acids, antioxidants and vitamin E, giving it nutritive and skin protective properties.21 It may actually help soothe skin problems like acne, eczema22 and rosacea.23
Milk thistle oil is also commonly added to cosmetics. Here’s one way to use milk thistle oil for your hair, according to the blog Naturally Curly: Massage the diluted oil (add one drop of milk thistle oil to 10 drops of your preferred carrier oil) all over your scalp 10 minutes before bath time, and then cleanse and style as usual.24