Milk Thistle

Top Milk ThistleSilybum marianum or milk thistle is a thorny herb that has detoxifying, antioxidant and anti-inflammatory properties. It is believed to have originated in the Mediterranean or the southeast coast of England, and has been introduced to warm climates such as Australia and New Zealand where it grows so prolifically, it is considered a weed. With cultivation in many parts of the world, Silybum has a wide range of common names including blessed thistle, cardus marianus, St Mary’s thistle, Scotch thistle and more.

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Milk thistle has been used in traditional herbal medicine for over 2,000 years, from the times of Dioscorides in Ancient Greece through to modern day. Refined milk thistle extract is still a popular therapy with modern-day herbalists and naturopaths.

The extract is made from the seeds of the flower, where all of the active constituents are found.

Concentrated milk thistle extracts contain high amounts of silymarin (a collection of flavanoids and polyphenolics), silybin, and fatty acids such as linoleic acid.

How to take milk thistle6 Best Ways To Use Milk Thistle

#1 Milk Thistle for Liver Health

Milk thistle has been used historically to treat a range of liver conditions including hepatitis and alcoholic liver disease.

In modern research, in vitro studies have shown that silymarin can protect liver cells against damage caused by a huge range of toxins, including ethanol (alcohol), cyclosporin, paracetamol, and iron overload [1] [2] [3].

The exact mechanisms behind silymarin’s powerful protective actions is currently unknown, but researchers believe it may be a combination of antioxidant, free radical scavenging, and toxin blockade modes of action.

Toxin Blockage: Silymarin and silybin are able to incorporate themselves into the cellular membranes of hepatocytes (liver cells). Once there, they can change the structure of a cell’s membrane to make it more resilient against toxin-induced attacks. They can also bind to target receptor sites that toxins would otherwise bind to.

Iron Chelation: Iron overload can cause liver toxicity and scarring. Silymarin and silybin can reduce the damage through antioxidant activity, but recent studies have also shown that these molecules can bind to excess iron and deliver it out of the body – this is a process known as “chelation” and it effectively protects the liver and other tissues against oxidative damage caused by iron overload. [4] NB: This is a particularly useful herb for people with hemochromatosis!

Interestingly: Milk thistle not only protects the liver against damage, it goes a step further – in vitro studies have shown that silymarin can accelerate the rate that liver cells regenerate after they have been damaged! [5]

#2 Milk Thistle for Cholesterol Levels

Milk thistle has been shown to stop the absorption of cholesterol in the digestive tract while working within the liver to slow down the production of new cholesterol, too.

  • Silymarin can inhibit the action of HMA-CoA reductase – this is the enzyme that switches “on” the pathway that creates cholesterol. [5]

A randomized, double-blind and placebo-controlled clinical trial of 51 patients with type 2 diabetes looked at the effects of milk thistle extract on biomarkers of metabolic syndrome. After four months, the participants who took 200mg of silymarin extract three times each day experienced a significant decrease in total cholesterol, LDL cholesterol and triglycerides levels [6].

#3 Milk Thistle for Diabetes

As well as protecting against cardiovascular complications of metabolic syndrome, milk thistle may help to control diabetes.

A landmark study in 1997 examined to effects of silymarin extracts on insulin resistance in diabetics. The six-month open trial found that silymarin not only lowered fasting glucose levels within one month but that the decrease continued steadily for the remaining five months of the trial. Notably, this didn’t lead to any increase in hypoglycaemic episodes.

The study also found improvements in two major biomarkers of glucose control (glycosalated haemoglobin and glucosuria), suggesting that milk thistle can support diabetics through a variety of mechanisms [7].

#4 Milk Thistle for Digestive Health

Milk thistle is a traditional bitter used in tonics for upset stomachs, heart burn and stomach ulcers. It has been shown to reduce stomach acid output, increase protective secretions, and reduce inflammation in the oesophagus, stomach and small intestine.

Studies have shown that it can promote appetite, support digestion of fatty foods, and protect against stomach ulcers, mild allergic reactions, and a range of digestive upsets [8].

An all-round digestive aid, milk thistle can be taken before meals to stimulate appetite and reduce bloating.

#5 Milk Thistle and Hormones

The evidence is very limited on this topic, but milk thistle may have a slight estrogen mimicking effect that may help to protect against post-menopausal conditions such as osteoporosis [9]. Keep in mind that the studies suggesting this effect only use animal subjects – there’s no data on this in humans and this is not a traditional use for milk thistle.

Meanwhile, the thorny herb has been used traditionally as a galactogogue – a herb that promotes lactation and increases breast milk supply. It does like by stimulating the hormone prolactin.

  • Two reviews of popular herbal supplements taken to support breast feeding concluded that, despite its long history of successful use, the available studies on silymarin are not strong enough and further research is required to really ascertain its efficacy. [10][11]

#6 Milk Thistle and Antioxidants

Milk thistle itself is rich in antioxidants, while its active constituents further promote antioxidant activity in the body by activating enzymes and boosting levels of glutathione.

Studies have shown that silymarin regenerates antioxidant enzymes like super oxide dismutase and glutathione dismutase, as well as free radical scavengers such as vitamin C.

Further research shows that silybum may even be a powerful antioxidant itself, and can reduce oxidative stress throughout the body. [12]

With powerful antioxidant activity on its side, milk thistle can:

  • Prevent signs of ageing
  • Slow down the development of many diseases
  • Support immune system function
  • Stabilize cells against mutation and damage
  • Protect neurons, heart tissue, capillaries and nerves

How To Take Milk Thistle

CAUTION: Do not “wildcraft” milk thistle without the guidance of a qualified and experienced herbalist. Consuming different thistles that look similar to true milk thistle can be toxic and deadly.

Interactions & Contraindications

  • Do NOT take milk thistle if you have a known allergy to the Asteraceae family of plants.
  • There is insufficient information available to determine safety in pregnancy.

Milk thistle may interact with medications:

  1. Cisplatin: Milk thistle may reduce toxic effects while enhancing antitumor activity. Use ONLY under professional supervision.
  2. Doxorubicin: Milk thistle may reduce cardiotoxicity. Use ONLY under professional supervision.

Possible Side Effects

Milk thistle is believed to be an especially safe herb, although all potential risks are unknown. There are rare reports of allergic reactions, and slightly more common instances of diarrhea and digestive discomfort. Stop taking milk thistle if you experience any signs of allergic reaction such as swelling of the lips, tongue or face; hives; closing of the throat or difficulty breathing.

Dosage Ranges

Generally, an average daily recommended dose is 12–15 g of milk thistle seed (equivalent to 200–400 mg silymarin), usually in divided doses.

  • Liquid extract (1:1): 4–9 mL/day
  • Liquid extract (1:2): 30–60 mL per week.

Speak to a qualified herbalist or naturopath for personalized advice.

Best 5 Milk Thistle Supplements

#5 Eclectic Institute Milk Thistle (600mg, 240 capsules)

Milk ThistleEclectic Institute offer a flash-frozen and freeze-dried milk thistle supplement – this form of processing is particularly pure, and these capsules contain nothing else! That’s right – just milk thistle! However, each capsule contains 600mg of milk thistle and a standardized dose of up to 30mg silymarin. This isn’t a hard-hitting heavy dose by any stretch – you would need to take 10 capsules or more per day to reach a therapeutic level. This is a great choice if you are looking to add some gentle liver support to your daily supplement program.

#4 The Republic of Tea Organic Milk Thistle Tea (36 tea bags)

Milk Thistle TeaIf you are looking for a gentle way to support your liver every day, you’ve found it. Milk thistle tea tastes quite herbacious and The Republic of Tea have added natural grapefruit and orange flavorings (derived from pure essential oils of fresh fruit), making this a fresh-tasting and invigorating morning brew that is designed for optimum liver support. Herbal infusion is the traditional way of taking milk thistle and, if taken often enough, is just as effective as occasional supplementation. Be sure to let each cup brew for 10 – 15 minutes for maximum therapeutic benefits!

#3 Nature’s Answer Alcohol-Free Liquid Milk Thistle Extract (2 fluid ounces)

Milk Thistle ExtractThere are two main reasons to opt for a liquid milk thistle extract – 1. it’s much easier to swallow than capsules or pills, and 2. taking the liquid before a meal can stimulate appetite and help to digest fatty meals. Nature’s Answer offer an alcohol-free extract, and each dose is the equivilent of 2,000mg of milk thistle. If you check out the reviews on this extract, you’ll find that people are giving it to their pets too – must taste pretty good if cats will happily drink it, right?!

#2 OmniBiotics Organic Milk Thistle Extract (375mg, 120 capsules)

Omni Biotics Milk ThistleOmniBiotics offer this 4:1 concentrated silymarin extract, containing the equivalent of 1,500mg of milk thistle in each capsule. The formulation is third-party tested to ensure quality and potency, and the product has been certified organic by the CCOF. These vegetarian-friendly capsules are quite large but you can open them up and stir the powder into water for easier swallowing. This is a great choice if you’re looking for a high quality, organic milk thistle extract.

#1 PureCo Organic Milk Thistle 24:1 Extract (80% silymarin, 250mg, 60 capsules)

PureCo Milk ThistlePureCo have created a highly concentrated 24:1 milk thistle extract with a standardised dose of 80% silymarin in each capsule. Each dose is equivalent to 6g of milk thistle – just two capsules per day is all you need to reach a therapeutic dose for liver support. Everything in this supplement is non-GMO and organic – from the milk thistle through to the traces of organic rice concentrate that PureCo use as a natural flow agent. This product is completely vegan-friendly, gluten free and comes with a 100% money-back guarantee! If you’re looking for high quality, highly concentrated and convenient milk thistle – this is it!

Further Reading:


About James Lyons

James Lyons (BHSc Nutritional Medicine) is a clinical nutritionist, medical writer, and educator. He specialises in plant-based nutrition and is passionate about improving public access to reliable and accurate health information.

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