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Milk Thistle: Good for the Liver or Too Many Side Effects?

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Milk thistle benefits - Dr. Axe

Milk thistle is a natural herb with antioxidant and anti-inflammatory properties. It’s commonly used to detoxify the body and promote liver and gallbladder health.

Also known by its scientific name, Silybum marianum, milk thistle grows mostly in California, although it can be grown in many other warm climates as well.

As an herb that’s considered a “hepatic, galactogogue, demulcent and cholagogue,” milk thistle is considered one of the most common natural supplements for liver disorders in the U.S., thanks to its many health benefits.

Other benefits include promoting healthy digestive function, increasing bile production, decreasing inflammation and soothing the mucous membranes throughout the body.

What Is Milk Thistle?

The milk thistle plant is a popular herb that has actually been used for over 2,000 years. In fact, Greek physician and botanist Dioscorides was the first to describe milk thistle’s healing properties back in the year 40 A.D.

The plant is native to the Mediterranean region and a member of the Asteraceae plant family, which also includes other plants like sunflowers and daisies.

This healing herb gets its name from the milky-white liquid that runs off of the plant’s leaves when they’re crushed. The actual leaves of the plant also have a spotted white pattern that makes them look as if they’ve been dunked in milk. It’s also known as St. Mary’s thistle, holy thistle and silybum.

Milk thistle is commonly used for everything from weight loss to skin health to promoting breast milk production. However, while there are many different potential benefits, it is most well-known for being a natural liver supporter and is sometimes used to help treat liver diseases such as cirrhosis, jaundice and hepatitis, as well as gallbladder problems.

It’s also often used to increase breast milk production, with one study showing that certain extracts in milk thistle could increase daily milk production by up to 86 percent.

There are a variety of milk thistle products available, and the seeds and leaves of the milk thistle plant can be consumed either in pill, powder, tincture, extract or tea form.

The seeds can actually be eaten completely raw, too, but usually people prefer to take a milk thistle extract or supplement in order to consume a higher dose and see greater results.

Top 6 Benefits

1. Liver Detoxification and Health

As a liver support and liver aid, milk thistle acts as a powerful liver cleanser by rebuilding liver cells, reducing liver damage and removing toxins from the body that are processed through the liver.

Milk thistle is effective at naturally reversing toxicity in the body, including the harmful effects of alcohol consumption, pesticides in our food supply, heavy metals in our water supply and pollution in the air that we breathe.

The liver is actually our largest internal organ and is responsible for performing a number of essential detoxifying functions. The condition of our blood throughout our whole body is mostly reliant on the health of our liver.

The liver helps remove toxicity and harmful substances from our blood, aids in hormone production, detoxifies the body, releases sugar into the bloodstream in order to give our body steady energy and secretes bile into our small intestine so fat can be absorbed from foods. You can see why liver problems and poor liver function can create so many problems!

Milk thistle has been historically used for a variety of liver diseases, including:

  • alcoholic liver disease
  • acute and chronic viral hepatitis
  • toxin-induced liver diseases

2. May Help Protect Against Cancer

Milk thistle seed is a great source of the antioxidant flavonoid called silymarin, which is actually composed of several other active compounds known as flavolignans.

Silymarin may help reduce the risk for cancer development (including breast cancer) by boosting the immune system, fighting DNA damage and reversing cancerous tumor growth. In addition to blocking breast cancer, test-tube and animal studies show that silmarin may also protect against several other types of cancer as well, including lung cancer and prostate cancer.

In 2007, after reviewing numerous studies involving milk thistle therapeutic treatments, researchers at the University of Minnesota reported:

There is strong preclinical evidence for silymarin’s hepatoprotective and anticarcinogenic effects, including inhibition of cancer cell growth in human prostate, skin, breast, and cervical cells.

About 50 percent to 70 percent of the silymarin molecules present within milk thistle are the type called silybin, also known as silibinin.

This antioxidant stimulates protein synthesis and changes the outside layer of healthy cells, keeping them protected from damage and mutation. It also inhibits toxins from dwelling in the body, helps with cell renewal and counteracts the harmful effects of pollutants, chemicals and heavy metals that can cause free radical damage.

Silymarin acts as a cancer protector by blocking the binding of toxins to the cell membrane receptors, according to researchers at the University Magna Graecia Department of Experimental and Clinical Medicine.

3. May Help Lower High Cholesterol

Milk thistle benefits heart health and helps lower high cholesterol levels by reducing inflammation, cleaning the blood and preventing oxidative stress damage within the arteries.

Although more formal research is still needed, preliminary studies show that when silymarin is used in combination with other traditional treatment methods, it can improve levels of total cholesterol, bad LDL cholesterol and triglycerides.

Something important to keep in mind, however, is that existing studies on possible heart benefits of milk thistle have only been done involving people with diabetes, who tend to have high cholesterol levels.

Therefore, at this time, it’s unclear if milk thistle has the same effects in people without diabetes and if it will be used to naturally lower cholesterol levels in the future.

4. May Help Control or Prevent Diabetes

According to the National Institute of Health, there’s some compelling research that shows that taking silymarin, the main chemical found in milk thistle, along with conventional treatments, can help control symptoms of type 2 diabetes by promoting better blood sugar control.

The valuable antioxidants found in milk thistle have been reported in experimental and clinical studies to help decrease blood sugar levels in people with insulin resistance.

One 2006 study conducted by the Department of Pharmacology at the Institute of Medicinal Plants found that when diabetic patients were given silymarin extract over a four-month period, their fasting blood sugar and insulin levels improved significantly compared to patients receiving a placebo.

This is likely true because the liver is partially responsible for regulating hormones, including the release of insulin into the bloodstream. Insulin is responsible for managing blood sugar levels in the blood, which is especially important for those with diabetes.

Related: Your Diabetic Diet Plan (A Guide for What to Eat with Diabetes)

5. May Help Prevent Gallstones

The liver is a major digestive organ, which helps process nutrients and toxins that enter our body through foods, water and air.

Because the liver and other digestive organs, like the gallbladder, pancreas, intestines and kidneys, work closely together to improve liver health, milk thistle is also able to help prevent gallstones and kidney stones.

Although research on this topic is limited, because of milk thistle’s ability to increase bile flow, protect against liver conditions like nonalcoholic fatty liver disease and promote liver detoxification, it may be useful in the prevention of gallstones.

Gallstones are formed when cholesterol and other matter within your bile bind together. This is problematic because they can become more solid and get lodged in the inner lining of your gallbladder.

6. Has Anti-Aging Effects

Thanks to the antioxidant content of milk thistle, the herb may actually help slow the aging process. This applies to both the surface of your skin and your organs, as antioxidants can protect your body from chronic disease.

Milk thistle’s protective qualities of the skin make it great for reducing visible signs of aging, so consuming milk thistle may be an easy way to prevent skin cancer and skin damage, such as acne, dark spots, wrinkles, lines and discoloration.

Although the research on this topic is limited to mostly animal studies, one trial published in Photochemistry and Photobiology found that silymarin protected the skin of mice from UV-induced oxidative stress and helped reduce inflammation.

The silymarin found in milk thistle can also protect against depletion of glutathione, which is a “master antioxidant” that’s extremely useful at helping prevent disease formation.

Glutathione’s biggest role is to help fight oxidative stress that leads to such diseases as cancer, diabetes, heart disease and neurodegenerative diseases like Alzheimer’s disease. It can help prevent damage to important cellular components caused by reactive oxygen species, such as free radicals.
Milk thistle benefits list - Dr. Axe

Milk Thistle Tea

Instead of using a milk thistle supplement, can also try consuming it in tea form to maximize the potential health benefits.

In fact, many companies make milk thistle tea by steeping the leaves and seeds from the plant.

You can also grow your own milk thistle and make homemade tea if you’re up for harvesting the plants. Each small plant head contains about 190 seeds that can be used in various ways.

If you purchase or grow a milk thistle plant, cut off the entire head and hang the plant upside down for about one week to draw out the seeds.

You can then crush the seeds and steep them, along with the leaves, to make tea, eat them raw or dry them into powder form. Keep the seeds and leaves in the freezer to make them last longer and retain their powerful nutrients.

Supplement Dosage

Because milk thistle is categorized as a supplement rather than a drug, it’s not subject to the same oversight and quality control from the Food and Drug Administration (FDA) that standard drugs are.

The amount of active ingredients can vary widely depending on the different preparation methods used and the brand. Currently, there are several different milk thistle tablets, capsules and softgels available on the market, all of which recommend different doses.

  • Although there is no standardized milk thistle dosage at this time, most people do best consuming between 20–300 milligrams daily.
  • If you’re taking milk thistle for the liver, the recommended daily intake of milk thistle is 150 milligrams, taken one to three times daily. This is a somewhat high dose that can act as a natural liver detox.
  • For ongoing use and liver support, take 50 to 150 milligrams daily.

Look for a high-quality product that’s between 50–150 milligrams of pure milk thistle extract per capsule so you can adjust the amount you are taking depending on your needs.

If you’re wondering what supplement is best, make sure to look for a company that sells a highly potent extract labeled at least 80 percent pure milk thistle extract.

Risks, Side Effects and Interactions

Milk thistle is generally considered safe and well-tolerated, with very few cases of side effects reported.

The most common side effects aren’t serious and include gastrointestinal upset, such as a mild laxative effect. When taken within the recommended dose range, however, it is thought to be effective and mostly free of allergic reactions.

Milk thistle may interact with some medications, including allergy medicines, anti-anxiety drugs and blood thinners, among others. If you are taking any medications, speak with your health care provider to prevent any milk thistle interactions before starting supplementation.

It also has estrogenic effects, meaning that it mimics the effects of estrogen in the body. If you have hormone-sensitive conditions such as uterine fibroids, endometriosis or ovarian cancer, you should consult with your doctor before starting supplementation.

Also note that antioxidants like those found in milk thistle have been shown to possibly interfere with the efficacy of some cancer chemotherapy drugs by protecting cancer cells from cell death.

Finally, keep in mind that, although many holistic practitioners recommend milk thistle for dogs to help promote liver health, it’s best to talk to your vet before starting supplementation to keep your furry friends safe.

Final Thoughts

  • What is milk thistle? This powerful plant is native to the Mediterranean, but is used around the world as a natural remedy for a wide variety of different ailments.
  • Human, test-tube and animal studies show that it may help promote liver health, protect against cancer, lower cholesterol levels, prevent type 2 diabetes, protect against gallstones and slow signs of aging.
  • It can be consumed in tea, tincture, extract, pill or powder form, making it easy to incorporate into your daily diet.
  • Dosage recommendations can range, but most advise taking anywhere between 20–300 milligrams daily.
  • Although it’s generally safe, you should talk to your doctor before starting supplementation if you are taking any medications or experience side effects like digestive distress.
Josh Axe

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