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Ranking the best milk thistle extracts of 2021

Written by John Davis

Last updated: December 7, 2020

Milk thistle is a plant extract that’s been used for thousands of years, but recent scientific evidence has indicated that it is a very promising treatment for liver damage and toxicity.

It’s been used in everything from clinical trials for advanced liver disease to simple liver cleanse programs. Looking for the best milk thistle supplements?

Our research team looked into what’s on the market and ranked the top ten.


1. LiverMD Liver Health Formula

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When it comes to your liver, you do not want to mess around.

LiverMD is a premium choice, but it’s worth it because of its patented version of milk thistle that was specifically developed to improve its absorption into your body.

(and also proven to be 10x more bioavailable than just the milk thistle extract itself)

Each serving comes with 80 mg of milk thistle extract, but because of its formulation, you get the same value you would get from 800 mg of just the straight extract.

Add to this all the other powerful liver supporting ingredients that come in this supplement — Vitamin E, N-Acetyl Cysteine, Alpha Lipoic Acid, Zinc, and Selenium — and you have a product that is unmatched in its ability to protect and support your liver.

Bodynutrition’s #1 milk thistle and liver cleanse winner.

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2. PureCo Organic Milk Thistle

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PureCo offers a great milk thistle supplement that is highly concentrated, vegan-friendly, and also certified organic. For these reasons, it’s hard to beat.

Each capsule provides 250 mg of 24:1 milk thistle extract, so its effective dosage is equivalent to that of six grams of raw plant material, making it one of the best supplements on the market in terms of dosage.

The fact that it is organic is especially attractive for people looking for a liver cleanse because the organic certification means it’s far less likely that any pesticides or herbicides made it into the plant material.

3. Jarrow Formulas Milk Thistle

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The milk thistle supplement from Jarrow Formulas is a high dosage, high-concentration form of the plant extract, and it’s delivered in a vegan-friendly capsule too.

The plant extract is a 30:1 concentrate of milk thistle, so the 150 mg serving size is equal to 4.5 grams of raw milk thistle plant material.

Without much in the way of additives or preservatives, Jarrow Formulas Milk Thistle is an excellent supplement.

4. aSquared Nutrition Milk Thistle Extract

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aSquared Nutrition has one of the most simple and straightforward milk thistle supplements out there. While it is not particularly concentrated, the supplement is quite minimalist, as it has only three ingredients.

The 250 mg of 4:1 milk thistle extract, rice powder, and gelatin are the only three ingredients in the supplement, so if you really want to keep things simple for your body, this is the way to do it.

People looking for a high dosage may want to look elsewhere, but if all you need is the equivalent of one gram of milk thistle plant material, it’s a pretty good choice.

5. Puritan’s Pride Milk Thistle

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Puritan’s Pride provides a milk thistle supplement that is high in dose and low in added extras. Each capsule provides a healthy 250 mg of milk thistle extract at a 4:1 concentration, meaning that one serving is equal to one gram of raw milk thistle.

The supplement is delivered in a gelatin-based softgel, which makes it easy to absorb but also unsuitable for strict vegetarians and vegans–gelatin is animal-derived.

The caramel and titanium dioxide colorings might not be up everyone’s alley, but in terms of active ingredients, Puritan’s Pride is still a good choice.

6. Superior Labs Milk Thistle

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Superior Labs makes a milk thistle supplement that is moderate in dosage but fairly straightforward in its formulation.

Each vegan capsule, made from vegetable-derived cellulose, contains 250 mg of milk thistle extract, and nothing else, aside from rice powder.

It’s a pretty good choice if you want a simple milk thistle supplement and know that a higher dosage is not what you are looking for, but aside from that, it doesn’t have too many defining characteristics.

7. Thorne Research Liver Cleanse

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Thorne Research Liver Cleanse is a blend of several supplements, including milk thistle, that is designed to help your liver function better.

In addition to milk thistle, it features dandelion root, burdock extract, barberina, and uva-ursi extract. The main problem with this supplement is that all of the ingredients are hidden behind a proprietary blend, so it’s not possible to know how much of each ingredient you are getting per capsule.

8. FarmHaven Milk Thistle

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This combination supplement delivers milk thistle in a simple and moderate-dose format in a capsule that’s pretty clean as far as supplement design goes. 

However, beyond this simplicity, it doesn’t have much to distinguish itself from the other options on the market, which lands it lower in the rankings.

9. Herb Pharm Milk Thistle

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Herb Pharm has a milk thistle that’s in a pretty unconventional format: a liquid extract sold in a dropper bottle. This means that you can deliver essentially any dosage you want, though your are limited quite severely by the precision of the dropper vial.

It’s one possible option if you want to be able to incorporate milk thistle into shakes or smoothies, but most people will want to opt for a capsule-based milk thistle supplement.

10. Nature’s Bounty Milk Thistle

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Nature’s Bounty has a reputation for economical, simple versions of popular supplements, which makes its products somewhat hit or miss.

This is certainly the case here, as the milk thistle content is mediocre at 250 mg of a 4:1 extract, but the real problem is the excessive content of binders, stabilizers, and other additives that—based on what’s in the supplements made by other competitors—clearly don’t need to be in the supplement.

Category winners

Best milk thistle overall: LiverMD Liver Health Formula

LiverMD is the best all-around option thanks to its high dose of silymarin (the active ingredient in milk thistle extract) and its inclusion of other synergistic ingredients that help amplify the health-promoting benefits of silymarin. No other product includes such a well-rounded supplement design. 

Best milk thistle for older adults: Jarrow Formulas Milk Thistle

With its moderate dosage and ultra-pure formulation, Jarrow Formulas Milk Thistle is our favorite for older adults. Keeping the ingredients simple means there’s less of a chance for unintended interactions with other supplements you may be taking. 

Best milk thistle for hangovers: aSquared Nutrition Milk Thistle Extract

A long night partying can do a number to your liver, and can leave you feeling pretty out of it. For hangovers, try aSquared Nutrition Milk Thistle Extract—it’s got a moderate dose of milk thistle extract to potentially avoid some of the damage to your liver caused by the metabolites of alcohol that circulate in your system the morning after a night out.

Best milk thistle for liver health: LiverMD Liver Health Formula

LiverMD combines milk thistle with essential trace minerals for liver health, including selenium and zinc, for a powerful liver health promoting effect. These ingredients, combined with alpha-lipoic acid and NAC, make for the best liver health formulation on the market. 

Best milk thistle for detox: Pure Co Organic Liver Cleanse

Milk thistle’s liver-promoting effects make it a popular component of detox diets and detox supplementation regimens. For this purpose, we recommend Pure Co Organic Liver Cleanse, which combines the cleansing capabilities of milk thistle with the detox power of dandelion root and artichoke leaf.

Best milk thistle for allergies: Jarrow Formulas Milk Thistle

The research on milk thistle for allergies is preliminary, but animal models do suggest that moderate amounts of silymarin (the active ingredient in milk thistle) could reduce allergy symptoms. Jarrow Formulas Milk Thistle is your best bet on this front, with its standardized 30:1 silymarin content.

Who should buy milk thistle extract?

Milk thistle extract is a supplement whose application is very highly targeted. Unlike broad-spectrum antioxidants like vitamin C or resveratrol, which have systemic effects and systemic benefits, milk thistle extract is primarily beneficial for your liver.

It has been studied in research ranging from cellular studies to clinical trials in humans that are all focused on repairing liver cells that have been damaged by disease or a poor lifestyle, or preventing future damage to the liver.

While the liver is a robust organ, it is vulnerable to damage from viruses like hepatitis, scarring and damage from excessive alcohol consumption, and the buildup of fat deposits that can result as a result of heavy alcohol consumption, type two diabetes, obesity, or excessive consumption of processed foods (mostly sugar and refined carbohydrates).

Since these types of conditions affect a large proportion of people, there’s quite a lot of interest in using milk thistle to repair liver damage, or at least prevent its progression.

While milk thistle is definitely not a replacement for proper medical treatment for any kind of liver condition, some people find it a useful supplement for liver health, liver protection, and liver repair. 

How we ranked

We based our rankings off the kinds of milk thistle formulations that have been used in scientific research. From all of the milk thistle supplements available on the market, we chose to look at only those that were available in liquid, capsule, or softgel formulations.

We had two reasons for this decision. First, these are the only kinds of milk thistle that have been rigorously studied in scientific research. While raw or bulk forms of milk thistle are available, and some are quite popular, these have not been studied with the same level of rigor.

Second, some research has indicated that these forms of milk thistle are more likely to be contaminated with toxin-producing fungi, which is definitely something you want to avoid.

On the topic of contaminants and impurities, we next looked for products that used good manufacturing processes or, preferably, had independent lab certifications for their purity.

We next looked at the dosage; we were looking for supplements that had research-supported doses of between about 160 to 560 mg per day. If a supplement did not make it easy to take a dosage that was supported by the scientific literature, we eliminated it from consideration for our rankings. 

When it comes to liquid versus solid (i.e. capsule based) supplements, there are arguments for both sides: liquid supplements are easier to mix into shakes or smoothies, and are a real lifesaver if you don’t like to or can’t swallow traditional capsules.

However, capsules make it much easier to get a prespecified dose, because measuring out liquid volumes using an elixir-like liquid supplement is tricky to say the least.

On balance, capsules come out ahead for most people, which is why the products at the top of our rankings are all capsule-based supplements. Still, we kept a few of the best liquid form milk thistle supplements in our rankings for the niche applications that they are suited for. 

The remaining products represent the best milk thistle extract supplements on the market right now. If you are looking for an herbally-based supplement that may help improve your liver health, look no further than these supplements. 


For a kick start to detox and cleanse your liver, a milk thistle supplement is a great method. Milk thistle contains active ingredients that appear to boost liver function and help reduce damage to the liver that’s resulted from excessive use of alcohol in the past.

While milk thistle has a long history as a “liver tonic” or an herbal remedy for organ problems, its benefits are rooted squarely in solid medical research.

Milk thistle has been a strong candidate for therapy in liver disease, indicating that it has several different properties that assist with liver function.

According to a review article by researchers at Oregon Health Sciences University published in the American Journal of Gastroenterology, milk thistle appears to protect the liver through a number of mechanisms (1).

First, it seems to shield DNA inside the liver from damage, in part by functioning as an antioxidant to clean out free radicals in the liver.

Milk thistle also appears to increase the rate of synthesis of proteins in the liver. This increased rate of protein synthesis helps the liver repair itself.

Finally, milk thistle absorbs calcium and iron in the liver, which the authors claim has a positive effect on liver health.

Other research by David D.J. Kroll, Heather S. Shaw, and Nicholas H. Oberlies suggests that milk thistle can accomplish all of this with minimal interaction with other biologically active compounds (2).

This is a highly desirable quality for an herbal supplement for liver issues, because any drug interactions could have strong negative effects on the liver, especially if it was not at top capacity to begin with.

Milk thistle may also be helpful for rehabilitating livers that have been damaged by excessive alcohol use. That was the conclusion of a study published in the journal Phytotherapy Research by researchers in Italy (3).

In a review of several studies on animal models, they showed that milk thistle is effective at reducing damage from a number of toxic compounds to the liver, and repairs the type of damage typically seen in alcohol-related liver damage.

While it can’t fully reverse the damaging effects of chronic, excessive alcohol consumption, there does seem to be evidence that milk thistle can contribute to reducing and repairing the damage to the liver.

A systematic review published in 2005 came to the same conclusion (4). Researchers at the University of Washington School of Medicine concluded that, while evidence is still emerging, the current state of the science was very promising and the authors recommended additional clinical trials in the future to study the use of milk thistle in treating alcoholic liver damage.

Milk thistle reduces oxidative damage in the liver. The primary mechanism by which milk thistle appears to help alcoholic liver damage is reduction of the oxidative damage to the liver from ethanol (i.e. drinking alcohol). 

This was what researchers in India discovered when they exposed rats to high doses of alcohol with or without a milk thistle supplement as part of their diet (5).

The milk thistle reduced biomarkers of oxidative damage in the rats’ blood, similar to the effects of a high-dose antioxidant used as a comparison.

Notably, the researchers found better results when milk thistle was used and alcohol was avoided—you can interpret this to mean that milk thistle isn’t a ticket to keep drinking heavily and continue to damage your liver.

Milk thistle that has been extracted and packaged in a liquid or capsule is less likely to be contaminated with fungal toxins than raw milk thistle or milk thistle seeds. While purified milk thistle extract appears to be fairly safe, some scientists and consumer advocates have expressed concern over contamination of milk thistle plant materials with fungi that produce toxic compounds (6).

Various studies have evaluated the presence of these mycotoxins in supplements, including milk thistle (7), but one of the most important studies was conducted at researchers for the Center for Food Safety and Applied Nutrition at the Food and Drug Administration (8).

This study looked at the presence of mycotoxins in a wide variety of milk thistle extracts available on the market. The researchers found that the highest concentration of mycotoxins was in milk thistle seeds, with high concentrations of toxins also being found in supplements that include raw thistle plant material, or chopped milk thistle herb.

On the positive side, the level of contamination in milk thistle supplements that were in liquid form or in capsules or softgels was far lower.

In fact, in this study, live fungal samples were not found in any of the extract-based supplements, though other work has indicated that even these supplements can be contaminated by toxins that are produced by these fungi.

In any case, based on this research, taking a milk thistle supplement that comes from an extract-based product is still a better idea than working with raw plant material. That’s why all of the supplements in our rankings are either liquid-based or capsule-based. 

Side effects

As far as supplements go, milk thistle seems to be quite safe.

A report published in the scientific journal Integrative Cancer Therapies in 2007 noted that milk thistle is quite inert when it comes to interactions with prescription medications (9). 

While a number of studies mention side effects ranging from gastrointestinal problems to headaches to skin rashes, a systematic review notes that randomized clinical trials found more or less the same rate of side effects in control groups (who received an inert placebo pill) as in the experimental groups (10).

This implies that the effects were not actually related to the milk thistle supplement, and were instead random occurrences.

While small, there is a possibility that milk thistle could interact with other pharmaceutical drugs that you are taking.

If you take prescription medication, or if you have liver disease, you should ask your doctor about the possibility for any undesirable side effects due to interactions between milk thistle and your current medications.

Some emerging research based on animal studies has suggested that consuming milk thistle alongside alcohol could accelerate the progress of liver cancer.

In a study on mice bred specifically to develop liver cancer, researchers at Carolinas Medical Center tested the effects of a milk thistle extract on liver damage, both in mice with no other modifications to their typical diet, and to mice who were consuming alcohol (11).

The researchers found that the milk thistle extract prevented a small amount of liver damage early on during the progression of liver cancer, but, when combined with regular alcohol consumption, liver cancer progressed more rapidly.

Since milk thistle extract is thought to exert its protective benefits primarily through antioxidant effects, the reasons for this increase in cancer progression might be due to a paradoxical relationship that’s also been seen with supplements like vitamin E: among people at a high risk for cancer (smokers, for example), very high levels of antioxidants can actually increase the rate of cancer progression.

While this study in mice is a long way off from demonstrating the same effect in humans, taking milk thistle extract might not be a good idea if you are a heavy drinker.

Of course, heavy drinking alone is enough to substantially increase your risk for liver cancer and liver damage, so your first order of business should be to cut down on your alcohol consumption if you want to improve your liver health.

Milk thistle is also vulnerable to contamination by fungi that produce toxins, which has led some researchers to express concern about the potential that these toxins could make their way into milk thistle extract supplements (12).

A 2015 study in the Journal of Agricultural and Food Chemistry used high-performance analytical chemistry techniques to demonstrate that these mycotoxins were common in several different types of supplements, and that milk thistle supplements were the category of supplement that had the highest levels of contamination (13).

As noted earlier, the safest supplements are those that are liquid, capsule, or softgel-based, with raw milk thistle and cut milk thistle herb being the most likely to be contaminated, according to research published in 2013 (14). 

Recommended dosage

A wide range of clinical trials have tested the efficacy of milk thistle supplements, and they’ve used a broad range of doses.

As reported in a scientific article by Janice Post-White, Elena J. Ladas, and Kara M. Kelly, the dosage in these studies ranges from 160 mg of milk thistle extract per day (usually standardized to 80% silymarin) up to 560 mg per day (15).

More studies have used the higher end of this dosage range, so something around 500 mg of milk thistle extract is what you should aim for if you want to replicate the most successful clinical studies.


Q: What is milk thistle? 

A: Milk thistle is a plant that’s found around the world. It’s related to ragweed, a common allergen, but milk thistle is most famous for being a source of biologically active compounds that could help improve liver health and even treat liver disease.

Silymarin is the official title for the biologically active molecules found in milk thistle extract that are thought to help improve liver health; these compounds appear to exert an antioxidant effect that reduces damage to the liver and stimulates liver cell repair and regeneration according to some clinical literature. 

Q: How does milk thistle helps the liver? 

A: The mechanism of action for milk thistle is thought to be related to the antioxidant effects of silymarin and its related compounds. Unlike systemic antioxidants like astaxanthin, the effects of milk thistle (to the extent to which they exist) appear to be concentrated in the liver.

Since conditions that cause liver damage, like fatty liver disease, hepatitis infection, and type two diabetes, are associated with inflammatory responses and oxidative damage in the liver at the cellular level, it’s at least plausible that antioxidant (and thus anti-inflammatory) activity from milk thistle could be the reason why some studies have found that it is beneficial for liver health and liver repair. 

Q: What does milk thistle interact with? 

A: Several studies have been conducted on the potential for milk thistle to interact with pharmaceuticals, with mixed results.

When it comes to the purified forms of silymarin, the biologically active category of compounds found in milk thistle extract, the potential for drug interactions appears to be quite low (16).

However, varying preparations of milk thistle may contain other compounds that do interact with prescription medication. Milk thistle extract does decrease the activity of an enzyme called cytochrome P-450, which plays an important role in drug metabolism, as well as other drug metabolism related enzymes (17).

Because the number of potential drugs that milk thistle could interact with is enormous, it’s always a good idea to talk to your doctor first before taking any new supplement if you are on prescription medications. 

Q: Does milk thistle have weight loss benefits? 

A: Milk thistle is not known to be an effective weight loss supplement, at least for the time being. However, its potential liver protecting effects could make it a useful adjunct for people who are overweight or obese.

Since excess body fat is known to cause liver damage due to the accumulation of fat deposits in liver tissue, taking a supplement like milk thistle for liver protection could be a good idea while you are working on losing weight.

While nothing can replace the benefits of actually losing weight, protecting your liver while working on doing so might be a good choice. 

Q: How do you take milk thistle? 

A: Whether your milk thistle supplement of choice comes in liquid or capsule form, it should be taken two to three times per day.

Divide your target dosage up into halves or thirds, and take one dose in the morning, possibly one in the afternoon, and one in the evening.

Milk thistle has a fairly short half-life, meaning that it is absorbed and excreted fairly quickly by your body. To follow the research trials as closely as possible, you’ll want to take milk thistle regularly for at least a few months, as this is the minimum observation period that’s typically used to detect benefits on liver health. 

Q: How long does milk thistle take to work? 

A: Milk thistle is absorbed pretty quickly in your body, but most research trials on using it to repair liver damage, or prevent future liver damage, are at least a couple of months long.

The time course of changes in liver function is long, so you shouldn’t expect to see improvements in liver health immediately. A trial published in 2012, for example, used an observation period of six months to evaluate the efficacy of milk thistle (18). 

Q: Should you take milk thistle in the morning or at night?

A: Milk thistle is absorbed and excreted pretty rapidly, which suggests that you should take it both at night and in the morning.

According to one study published in the journal Drug Metabolism and Disposition in 2008, the biologically active compounds in milk thistle have an elimination half life that ranges from one to eight hours depending on the specific compound in question (19).

That means that half the effective dose has been eliminated after one to eight hours. Because of this relatively short “active time” in your body, most clinical research uses at least two doses of milk thistle extract per day, and some use three: morning, afternoon, and night. 

Related articles


Milk thistle is a supplement with a strong body of research supportings its use for both treating liver disease and as part of liver cleanse or detoxification for people who think they’ve had subpar liver health.

Milk thistle, and its active ingredient silymarin, work to improve liver function by halting oxidative damage and through increasing synthesis of proteins for liver repair. For best results, you should follow a protocol that’s been tested in scientific research.

The optimal dose seems to be in the neighborhood of 500 mg of milk thistle extract (with 80% silymarin content) per day. Because of the evidence for its efficacy, milk thistle can be used as a core component of a liver cleanse or detox.

For BodyNutrition’s #1 milk thistle and liver cleanse, click here.


John Davis

John Davis is a Minneapolis-based health and fitness writer with over 7 years of experience researching the science of high performance athletics, long-term health, nutrition, and wellness. As a trained scientist, he digs deep into the medical, nutritional, and epidemiological literature to uncover the keys to healthy living through better nutrition.