Milk Thistle: Benefits, Side Effects, Precautions And More 2024

Milk thistle is also called Silybum marianum.^[1] This name^[2] is often used interchangeably with milk thistle. The plant is a vibrant purple with white veins and holds a high concentration of plant compounds called silymarin. Silymarin provides milk thistle health benefits such as anti-inflammatory, anti-viral, and antioxidant properties. Read to know the proven health benefits of consuming milk thistle. 

Benefits Of Milk Thistle

Support Liver Health

Milk thistle is best known for its liver benefits. It has been studied for its protective effects and treatment^[4] of liver function and disease. Some research^[5] suggests that these effects are due to their ability to stabilize the liver cell walls, thus preventing toxins from entering liver cells. This results in decreased liver inflammation. Milk thistle also has antioxidant capabilities meaning it fights off free radical damage caused by unstable molecules. 

The research on the liver benefits of milk thistle is quite mixed. Unfortunately, while some studies^[6] show that silymarin helps reduce inflammation, others show it has no effect on liver health jeopardized by hepatitis C.  

For example, a major study^[7] found that silymarin doses above normal did not benefit people with hepatitis C. In this study, people had no change in virus or quality of life compared to patients who took the placebo. Therefore, there is no herbal remedy at this time that helps with the development, prevention, or treatment of hepatitis C. 

Aside from this exception, milk thistle is often used with other medical interventions to treat different liver diseases, such as non-alcoholic and alcoholic liver disease and sometimes liver cancer.  

One thing that milk thistle has been associated with^[8] is the decreased risk of death from ingestion of a poisonous mushroom called death cap mushroom. This mushroom is responsible for most deaths from eating foraged mushrooms every year. Once ingested, the mushroom causes liver damage and failure. However, milk thistle has been proven to mitigate its toxicity.

Cancer Prevention

Preliminary research^[9] suggests that silymarin may have preventative cancer effects due to its ability to:

• Prevent cancer cells from multiplying and dividing.
• Reduce cancer cell lifespan while preserving normal cell longevity.
• Cut off blood supply to tumors.

Some research^[10] also shows that silymarin can improve your protection against skin cancer. Other in-vitro studies^[11] suggest milk thistle may work in connection with chemotherapy drugs. However, all of this research is preliminary and still needs further human testing to discover the supplement’s advantages. 

Support Kidney Health

Kidney damage is a common complication of diabetes and often happens with type 1 and type 2 diabetes. If not treated, almost one-fourth to one-half of patients will develop end-stage renal failure within twenty years.  

The main reason for kidney damage in people with diabetes is thought to be caused by oxidative stress. Oxidative stress is when free radicals–unstable molecules outnumber antioxidants in our bodies. This dysbiosis can cause a host of problems, such as: 

• Diabetes.
• Heart disease.
• Hypertension.
• Parkinson’s. 
• Alzheimer’s.
• Cancer.

Diabetes-related kidney damage is thought to be caused by oxidative stress. Disturbingly, even people who control their blood sugar and blood pressure still might develop kidney disease and injury. 

However, silymarin is being studied^[12] for the treatment of kidney damage due to its anti-inflammatory and antioxidant capabilities. An animal study looked at the effect of milk thistle extract and its impact on kidney disease and oxidative stress. The milk thistle lessened kidney damage in mice with diabetes, documented by lower amounts of protein excreted through urine.  

Per the researchers of this study, milk thistle has multiple promising benefits for the kidneys. However, they need to research more to evaluate the potential benefits of higher doses of silymarin and possibly more extended treatment periods.   

Increase Breast Milk

Milk thistle might be an excellent addition to lactating mothers’ diets. There are currently minimal studies, but the thought is that milk thistle can boost breast milk production by increasing the hormone that produces milk, prolactin.  

One study^[13] found that breastfeeding women who ingested 420 milligrams of silymarin for two months were able to produce about 60 percent more breastmilk than women who took a placebo.  

Improve Skin Health

Milk thistle also has known benefits for the skin. For example, taking milk thistle can decrease acne severity. Acne is thought to be caused by inflammation in the skin; thus, due to milk thistle’s ability to reduce inflammation, it can be a potent, natural way to treat acne. 

One study^[14] showed that patients who ingested 200 milligrams of silymarin daily for eight weeks had 50 percent fewer acne outbreaks than those who took the placebo. Again, there are few studies to confirm these results, but this could provide a non-pharmaceutical way to treat acne.   

Lower Blood Sugar

The components of milk thistle could help improve a person’s sensitivity to insulin and thus lower blood sugars. Researchers^[15] believe milk thistle works similarly to diabetic medicines.  

A recent analysis^[16] found that type 2 diabetics who took a regular supplement of silymarin had lower hemoglobin A1C levels, a measure of blood sugar control over several months, and fasting glucose levels compared to those who did not.  

Additionally, the same study found people taking silymarin also had beneficial effects on several diabetic complications, including: 

• Diabetic nephropathy.
• Diabetic neuropathy.
• Non-alcoholic steatohepatitis, that is, “fatty liver”

The effects of this are mainly through its antioxidant properties. Unfortunately, the researchers noted the quality of these studies was low, and thus more research is needed to verify any recommendations. 

Aid Weight Loss

Some speculation is that milk thistle can benefit those struggling with weight loss. A 2020 study^[17] helped to confirm this suspicion:

• Mice were fed a high-fat diet for eight weeks.
• One group was given silibinin, another compound found in milk thistle; then researchers monitored both groups for weight gain and obesity development. 
• The supplement reversed the mice’s fatty liver disease and restored glucose balance in those fed the extract silibinin.
• They also had reversed hypertriglyceridemia, hyperinsulinemia, and hyperglycemia.  

This study demonstrates that milk thistle extract with silibinin can be used in the future as a potential treatment to manage obesity and obesity-related complications.  

Risks Of Taking Milk Thistle

Since milk thistle is natural, it is generally considered safe when taken orally.^[18] To further this point, in most studies in which people took high doses over long periods, less than one percent^[18] reported side effects.  

In that group, most side effects were linked to gastrointestinal issues such as bloating, nausea, and diarrhea.  

A few groups of people need to be mindful when taking milk thistle. These groups include:

Prenatal, Pregnant, And Postnatal Women

There is no research currently on the safety of milk thistle for these groups of women, so best to avoid and use caution.  

Allergies 

These can occur at any point in a person’s life. However, use extra caution when taking milk thistle, especially if you have allergies to ragweed or daisies–Asteraceae/Compositae family of plants. Call a medical professional immediately if you experience any of the following symptoms:

• Sneezing.
• Itchiness.
• Coughing.
• Wheezing.
• Shortness of breath.
• Rash.
• Hives.
• Diarrhea.
• Swelling of the tongue, lips, or throat.

People With Diabetes

Milk thistle can decrease blood sugar; thus, these effects may put people on diabetes treatment at a higher risk for low blood sugar. 

Precautions & Recommended Dose

Milk thistle supplements are not considered pharmaceutical drugs but nutritional supplements. Therefore, it is not subject to approval or quality testing by the Food and Drug Administration.^[19] Thus, the ingredients that make milk thistle potent and active can significantly vary among different brands.  

You can purchase milk thistle tea, capsules, soft gels, powders, and tablets. Some health food stores even carry milk thistle seeds. However, you will find that there is no standard milk thistle dosage; it comes in various ranges.  

Given there is no standard, the wide range of dose^[20] spans between 50 milligrams and 300 milligrams of milk thistle daily. Look for a product that contains pure milk thistle with limited other ingredients.  

Milk thistle is tolerated on average very well and is a natural plant supplement; thus, it has few side effects. Some people may ask, when should I take milk thistle? 

It is not known to keep you awake at night and does not cause stomach problems if taken without food. You can also consume it with meals with no side effects. Thus, there is no particular time of day when milk thistle is more or less potent or effective.

The Takeaway

Milk thistle is a vibrant purple flower with white veins used for various natural remedies and ailments. Studies have shown that milk thistle extract has multiple benefits, including promoting liver health, preventing cancer, and protecting against diabetes and diabetic complications such as renal damage.  

There are various ways to consume milk thistles on the market today. You can enjoy a cup of milk thistle tea or ingest supplements in tablet, extract, soft gel, or powdered form. Therefore, adding milk thistle to your daily diet is straightforward. Even though there is no standard dose, most medical providers suggest taking between 50 to 300 milligrams daily to see benefits.  

Although milk thistle is generally recognized as safe due to its natural origin, it is always best to consult your doctor or another professional medical provider before starting any new diet or supplement routine.   

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