Milk Thistle and Liver Health – Part 1

by Mike Arnold

Milk Thistle in History
Legend has it that as the Virgin Mary was passing by, some of her maternal mother’s milk was spilt upon the nearby thistle. This caused the veins within the leaves of the plant to turn milky-white and as tradition would have it, was also responsible for imparting this plant with its original and still current name; Milk Thistle.

The use of Milk Thistle (Silybum Marianum) as an herbal medicine dates back over 2,000 years to the ancient Greeks, although detailed references attesting to the herb’s healing powers were first noted by the Romans in the 1st century AD. Roman naturalist, Pliny the Elder (AD. 23-79) wrote extensively about its cleansing abilities, while the Roman physician, Dioscorides, later recommended that the plant’s seeds be used by those who had been bitten by snakes, particularly those who were most susceptible to the venom, such as infants. Given that the Milk Thistle plant contains many diverse parts, the fact that the seeds were recommended for consumption is quite astonishing, if not a matter of pure luck, as it is the seeds themselves which contain the active compound responsible for the plant’s liver rejuvenating/protective effects.

As time went by, the herb became more directly associated with the treatment of liver conditions. The connection was strengthened with the appearance of a prominent British herbalist, Nicholas Culpepper, who was a strong advocate of using the plant for various liver disorders, as well as other conditions involving the spleen. While his writings were widely disseminated at the time, there was still a great deal of ignorance present regarding the proper applications of this drug-like plant. This is evidenced in the many unwarranted recommendations of the day, such as the assertion that keeping the herb close to one’s person, such as in a coat pocket, would ward off snakes…or that nursing mothers would produce more healthful milk by including this herb as a part of their dietary regimen; a belief that no doubt arose from the fictitious claim that the Virgin Mary spilt her milk on the plant, which supposedly bestowed some type of divine quality upon it.

While some of these claims were way out in left field and lacked even the most basic credibility, things were starting to move in the right direction. By the turn of the 19th century, with ever-advancing science at our side, several German physicians proposed that Milk Thistle be used in the treatment of liver and blood issues. However, they did not base their recommendations on guesswork or other unproven information, but on the recent discovery of an unknown flavonol contained within the seeds of the Milk Thistle plant. This was a big step forward in solidifying Milk Thistle’s place in herbal medicine.

As German researchers continued to explore the medicinal properties of the plant, they discovered its ability to protect the livers of animals which had been poisoned with the extremely toxic carbon tetrachloride. Shortly thereafter, scientists identified and isolated Milk Thistle’s active constituent and having establishing the compound’s chemical constitution, it was given the name Silymarin. News of this revelation spread, providing scientists with a more focused area of research. As a result, a German physician by the name of Rademacher was credited with the creation of a Silymarin-based tincture, which is still included in some pharmacopeias today. Since then, no other plant derivative has been as extensively studied as Milk Thistle or more precisely, Silymarin.

In more recent times, Milk Thistle entered the supplement market in standardized form, which provided those with liver disorders a means of self-medicating. It can now be purchased from health food stores, vitamin shops, and online distributers. There are dozens of manufacturers selling Milk Thistle based products, which can vary widely in both purity & potency. In the last decade, the use of Milk Thistle products marketed specifically for steroid users has increased tremendously, due to in large part to the growing body of evidence supporting its hepatoprotective effects.

What is Milk Thistle-Silymarin?

Native to the Mediterranean, this hearty plant now grows on multiple continents, including Europe, North & South America, and Australia. It belongs to a group of flowering plants commonly known as thistles, which are typically characterized by sharp prickles covering part or all of the plant’s surface. This life-preserving adaptation is designed to discourage herbivorous animals from feeding on the plant; a most effective self-defense mechanism indeed.

More specifically, Milk thistle is a member of the Asteraceae family (also called compositae); a large group of plants comprised of over 23,000 species of trees, herbs, and shrubs. It grows between 5-10 feet tall, takes less than a year to reach full maturity, and thrives in dry, sunny weather. In some parts of the world its presence is viewed as an intrusion; with residents considering the plant more of a weed than a potentially health-preserving plant.

Within the seeds of the Milk Thistle plant, scientists have discovered 3 biochemicals responsible for the beneficial effects noted in the literature. These are silychristine, silydianin, and silybin (often referred to as silybinin). Of these, silybin is considered to be the most potent. Collectively, these 3 substances are known as Silymarin. Therefore, most manufacturers of Milk thistle have standardized their product to contain a high percentage of the active ingredient, Silymarin.


Pharmacodynamics is the study of the biochemical and physiological effects of drugs on the body and their mechanisms of action. Silymarin has a diverse range of effects on the body, many of which are mediated through their own unique mechanism of action. The antioxidant properties of Silymarin are one such example.

Silymarin functions as an antioxidant by reducing free radical production and lipid peroxidation, as well as influencing enzyme systems associated with glutathione and superoxide dismutase. This may assist the liver in carrying out its cleansing functions more efficiently. This has direct applications for oral AAS users, as the liver’s ability to minimize AAS induced hepatotoxicity is partially dependent on its ability to self-cleanse.

Silymarin has also been implicated in the regeneration of liver tissue through an increase in protein synthesis in injured livers. This stimulation of protein synthesis is an important step in the repair of hepatic injury and is critical for restoring structural proteins and enzymes damaged by hepatotoxins. Interestingly, this effect has only been observed in injured liver tissue, while test subjects with unimpaired livers were immune to this effect. While the exact mechanism of action remains unclear, the formation of ribosomes via regulation of RNA polymerase is a likely candidate. This is a reasonable conclusion given that previous studies conducted in rats have shown an increase in the formation of ribosomes and DNA synthesis. The benefits associated with this effect should be obvious in those suffering from drug/toxin induced liver damage (e.g. oral steroid use).

In addition to its inherent liver regenerating effects, Silymarin therapy offers the steroid user other benefits, as well. Oral steroid use is well known to cause inflammation of the liver, resulting in potential liver damage. Studies have shown that Silymarin exerts a strong anti-inflammatory effect in liver tissue through suppression of NF-κB-regulated gene products, which includes COX-2, LOX, inducible iNOS, TNF and IL-1. Therefore, the concomitant administration of Silymarin with oral AAS may help mitigate the inflammatory effects of oral AAS on the liver, improving overall liver function and health.

Lastly, Silymarin has been found effective in the prevention/treatment of hepatic fibrosis (liver scarring). This is accomplished by inhibiting the proliferation of satellite cells, which directly reduces the conversion of stellate cells into myofibroblasts. Ultimately, this down regulates gene expression of the components necessary for fibrosis. This is good news for AAS users, as fibrosis is a potential side effect of oral steroid use. While we have only covered a portion of Silymarin’s mechanisms of action in this section, further research into this area will reveal additional benefits connected to this extraordinary herb-based compound.

In part #2 of this 3-part series, we will explore multiple real-life cases of individuals who have been successfully treated with Milk Thistle after being diagnosed with various liver disorders. We will also take a look at some of the recent claims that Milk Thistle does not work and compare it directly against the available medical literature.

Part 2 coming soon…

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