General Health

Does Milk Thistle Help Your Liver?

Most drugs and plant extracts have something in common. They need the liver for metabolization.

In this regard, liver enzymes are specialized in detecting substances in the blood and clearing them.

And an individual with malfunctioning liver enzymes will have two problems-an exaggerated effect when they use medications. And a perilous obstacle in clearing the blood from toxins.

Medications usually use these enzymes to metabolize. And problems start when another drug is administered and uses the same pathway.

But milk thistle (Silybum marianum) is one of the few supplements that people use to improve liver function. As you will see in this article, it is an excellent aid to speed up and boost your liver to its maximum capacity.

What is milk thistle?

Milk thistle is the popular name of a flowering herb named Silybum marianum. It is a plant from the ragweed family, originally from European countries.

However, it is also found in many parts of North and South America. This plant is very popular as a substitute for coffee, and its leaves can be used in salads.

In our present-day, milk thistle extract has wide acceptance all over the world. Even doctors and specialists recommend milk thistle supplements in some instances. It is based on natural ingredients, but thoroughly tested and considered safe.

The active compound in milk thistle is known as silymarin. Instead of being a single substance, silymarin is considered to be a very complex array of substances. This group of substances in milk thistle include (1, 2):

  • Silybin A and B: They are by far the most critical substances in milk thistle. Most studies focus on silybin and its multiple health benefits, as you will see further down.

  • Isosilybin A and B: They have similar benefits, especially on the liver. However, not enough studies are yet made to confirm our findings.

  • Other flavonolignans: Milk thistle has other lesser-known flavonolignans. They have a similar name and chemical formula. Presumably, they can also have a similar function. However, their concentration is much lower, and there are not enough isolated studies.

  • Taxifolin: This is a common flavonoid we can find in conifers, some types of vinegar, and milk thistle. It has been studied for its chemopreventive properties. In other words, it may reduce the incidence of some types of cancer (3).

What are the health benefits of milk thistle?

Several studies have been made, and they support the use of milk thistle for these health benefits:

  • To promote the activity of hepatic enzymes: As an organ, the liver always depends on enzymes. They are useful to trigger metabolic processes, eliminate toxins, and much more. Some enzymes also help protect the liver’s health against these toxins, which accumulate in this area. They are potent antioxidants aiding in liver detox as well (4, 5).

    Milk thistle has an essential role in protecting the liver against free radicals. It stabilizes the liver cell membrane and may contribute to improving several liver-related diseases (6).As such, it is no wonder that patients may experience a reduction in TGO, TGP, and bilirubin. TGO and TGP are liver enzymes, and they should be on the liver, not on the blood. When they are found on the blood in high concentrations, it means that many liver cells are dying and releasing their contents to the outside. Bilirubin is piled up in the blood when there are no sufficient enzymes to convert it and eliminate it. So, both problems can be reduced by speeding up liver enzymes, as milk thistle does (7)

  • To repair liver structures: The liver is always subject to constant attacks, and this may cause liver problems. It is the center of your body detox, and many toxins converge in its structure. That’s why liver reparation is so essential. Milk thistle stimulates liver cells to replicate their DNA and create new healthy structures. It accelerates the normal process of recovery after liver damage. Thus, it can be recommended after chemicals or physical lesions to the liver (8).

  • To protect the liver against toxins: Milk thistle does not only speed up repair processes and liver enzymes. It also has a crucial role in protecting the liver injury against toxins. Researchers comment that silymarin may work as a barrier against toxins. Because there is a protective effect, and cells treated with toxic substances do not trigger accelerated death and other lesions when milk thistle extracts are around (9).

  • To slow down hepatic fibrosis: Hepatic fibrosis is a complicated process that may end up in cirrhosis. It starts with inflammation, lesions in the liver, and growing scars. In time, the liver structure is replaced with these prominent scars, known as fibrosis. Since normal tissue is replaced, the liver function is ultimately lost. But in some cases, milk thistle may slow down hepatic fibrosis. For example, patients with hepatitis C may improve their quality of life and slow down the process of fibrosis by using milk thistle (10)

  • To protect against hepatitis: Milk thistle also affects the hepatitis C virus. According to studies, it may prevent and treat chronic hepatitis (Viral hepatitis). Especially when interferon alpha is administered alongside. Silymarin inhibits the spread of the virus and has an anti-inflammatory effect. Both can improve the symptoms and quality of life of these patients (11).

  • In cases of thalassemia: Silymarin is not only helpful for the liver. It may also work in cases of thalassemia. This disease affects the structure of hemoglobin in red blood cells. These patients have an alteration in iron levels in the blood. Thus, they require an iron-lowering agent known as deferoxamine. According to research, milk thistle may help deferoxamine in normalizing circulating levels of iron in the blood (12).

  • It may be useful in certain types of cancer: According to studies, milk thistle may have an anti-cancer property as well. Researchers say that this effect is direct upon cancer cells. It may be especially helpful for patients with breast cancer, prostate cancer, and cervical cancer (13). Besides having an immediate effect, there’s also an indirect effect. The evidence points out that milk thistle may aid chemotherapy in fighting cancer. For example, it may be useful to heighten the effects of doxorubicin in breast cancer (14).

    Additional to this, milk thistle shows promise to reduce the risk of metastasis in prostate cancer. It slows down the differentiation of cells that destroy bone structures in cases of metastasis (15).

  • Other than this, other studies suggest a possible role in weight loss, liver cancer, and other conditions.

Can milk thistle help fatty liver?

For all of the above, the answer is an absolute yes. Milk thistle can protect your liver and slow down the progression of fatty liver disease. 

One of the problems with fatty liver disease is how liver fat causes inflammation and chronic damage. In time, nonalcoholic steatohepatitis or alcoholic liver disease starts causing fibrosis. But milk thistle can help us slow down this process, as mentioned above.

In case there’s a reduction in enzyme function, silymarin may also play a role. It speeds up liver metabolism and helps us recover our everyday function. This initial assumption is backed up by evidence. Some studies show a significant benefit in patients with nonalcoholic fatty liver disease. According to these studies, the effects include (16):

These trials are made with high-quality methodology, and their results are trustworthy. However, there is not yet a final word on the ideal formulation for fatty liver disease.

Some studies have a higher dose than others. In practice, this discrepancy may reduce the treatment effects for some patients, while others benefit fully from the administration of milk thistle. Thus, it is better to use this supplement as a co-adjutant treatment and diet, exercise, and medical treatments (16).

How to use milk thistle for fatty liver

You can find milk thistle in different presentations. They are all excellent and provide most of the benefits described above. However, some of them are better absorbed than others.

In the case of milk thistle, most of its substances are soluble in fatty acids. Thus, it should be administered with vehicle oil substances, such as olive oil. It may also be recommended to take your daily dose of milk thistle along with your foods.

That way, at least in theory, the dietary fat naturally found in your food aids the absorption of silymarin. For the same reason, it is also recommended in capsules or pills as opposed to infusions or milk thistle tea (17)

It can also be used with other extracts and supplements that may work synergically to improve liver disorders:

  • Alpha-lipoic acid: This substance works along with milk thistle in protecting the liver against free radicals. It activates an innate antioxidant called glutathione. It also slows down the degradation of antioxidant vitamins (vitamin E and vitamin C). Moreover, this substance has anti-inflammatory potential. Thus, it can be useful to reduce the incidence of liver cirrhosis (18, 19).

  • Turmeric: This is also an important antioxidant and anti-inflammatory agent. It has similar effects on the liver and works synergically with the milk thistle herb (20, 21). 

  • N-acetylcysteine: This is a very safe substance commonly known for cough management. However, it does have a significant effect on the liver, too. N-acetylcysteine is useful to treat acetaminophen overdose, which causes substantial damage to the liver. N-acetylcysteine protects the liver and prevents damage to cell DNA (22).

Are there safety concerns?

The milk thistle plant is one of the safest supplements we can try. There are no studies so far showing significant side effects at the standard milk thistle dosage. All groups of individuals tolerate the usual dosage-only a few experience gastrointestinal problems.

Among common gastrointestinal issues, it may have a mild laxative effect or cause nausea. However, these symptoms are usually seen in exaggerated doses. In each and every case, the symptoms improved after discontinuing the supplement or lowering the dose.

Even pregnant women can use milk thistle. It is recommended for women who have intrahepatic cholestasis. It does not harm the fetus and can be administered in children (23, 24).

There’s even one study that evaluated very high doses of milk thistle. The researchers used higher and higher doses to test for toxicity and found no significant effects for an extensive range.

Between 10-20 grams a day (more than 10,000 mg), there was an increase of bilirubin and hepatic enzymes, but it was asymptomatic. Thus, there is an extensive therapeutic range without reaching the toxic dose (25).

The only contraindication of milk thistle would be for allergic reactions. Anyone with an allergy to Asteraceae plants should not use milk thistle, either. Also, consider that this supplement is not to be used for hormone-sensitive cancer without a doctor’s supervision. It sometimes has a hormonal effect that may not be appropriate to some cases.

Are there any interactions with medications?

According to investigations about milk thistle, most of the interactions with medications are positive. Actually, milk thistle can be used to enhance the benefits of other medications.

Particular emphasis should be made with chemotherapy medications, for example. In the process, we could believe that the adverse effects of chemotherapy would increase as well. But that’s not the case. According to studies, milk thistle protects healthy cells while letting these drugs target cancer cells (26).

Other than that, the most common interaction comes from the modulation of liver enzymes. These enzymes are responsible for metabolizing other drugs. If they are stimulated by milk thistle, the organism may handle medicines differently. Thus, it is recommended to monitor chronic medication users if they start to consume milk thistle.

Dosing considerations for Milk Thistle

There’s no final word on using milk thistle, what dose works best, and other considerations. At least not published by health authorities.

There’s not a fixed milk thistle dosage for fatty liver or any other liver condition. However, we can use a milk thistle supplement according to evidence. By looking at the scientific studies above, we can consider a good dose for daily administration.

A typical dosage is 420 mg a day, usually consumed orally. Other studies show benefits with lower concentrations of 140 mg a day, and still others with 800 mg a day (27, 28, 29).

As you can see, there’s a wide variation. But all of these studies agree that milk thistle should be consumed continually to reach significant benefits. Otherwise, there won’t be enough blood levels, and it won’t make a difference. But if you consume for at least 12 weeks, the effects will start to show up on your liver and other organs.

Studies have shown that you can take this type of supplement for up to 41 months without any particular problem (30).


Milk thistles is a herbal remedy that has a wide array of benefits. Most of them are related to liver function. It protects the liver from toxins and oxidative stress and may slow down the progression of several diseases. It is also useful to enhance the effect of specific chemotherapy agents and has other applications.

Milk thistle can be used safely, even at extremely high doses. However, there’s not a guideline with a recommended dose. All we can do is look at the evidence and use the doses that worked for a given disease. They are usually between 150 mg and 800 mg a day.

More than that is not recommended, yet it is still safe to reach higher doses. Pregnant women and children can also use milk thistle without adverse effects.


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