An ancient medicinal plant and multifunctional herbal remedy for everything from liver disease to snake bites, milk thistle seed extract – otherwise known as silymarin – is an antioxidant-rich, natural anti-inflammatory substance with many promising potential health benefits. Keep reading to learn more about silymarin and how it may help you meet your health goals.
What is Silymarin?
Silymarin is a standardized extract from the seeds of milk thistle (Silybum marianum), an herb in the Asteraceae (daisy and ragweed) family, used to support healthy liver and gallbladder function, to help maintain healthy cholesterol and blood sugar levels, and to support healthy-looking skin, among other potential health benefits. It is native to Mediterranean countries but can also be found growing in North America, Mexico, southern Europe and Russia, and North Africa. This flowering plant has thorny leaves and bright purple flowers, of which its seeds or fruits are extracted for medicinal purposes. (1, 2)
Silymarin is available in dietary supplements such as capsules, tablets, powders, liquid extracts, and tea. It can be taken as a supplement on its own or in a combined formula for improved bioavailability with other herbs such as barberry root bark, black radish, wild yam root, fennel seed, or cloves, to name a few, to support liver health and many other important bodily functions.
How Silymarin Works
Silymarin contains a mixture of flavonolignans (silibinin – also known as silybin, as well as isosilibinin, silychristin, isosilychristin, and silydianin) and a flavonoid (taxifolin). (3) When milk thistle seeds have been processed into an ethanolic extract, they typically contain 65-80% of silymarin (concentrated from 1.5-3% of the plant) and 20-35% of fatty acids (including linoleic, oleic, and palmitic acids). Silymarin is a flavonoid, a type of plant-derived polyphenol with antioxidant properties. Flavonoids such as silymarin are a diverse group of phytonutrients (plant chemicals) that have been shown to exhibit antioxidant, anti-inflammatory, and neuroprotective activities, helping to combat microbial infection, support the immune system, promote detoxification, and regulate cell growth. (4, 5) Silymarin also has antifibrotic properties (supporting against fibrosis, the main cause of cardiovascular disease), antiproliferative properties (preventing the spread of malignant cell growth such as with tumors), and antiviral properties. (6)
The main bioactive compound within silymarin is silybin, which makes up 50-70% of its total composition and is considered the source of the substance’s antioxidant, anti-inflammatory, and antifibrotic properties. In fact, silybin actually helps conserve tissue glutathione – the part of cells that fights free radicals. (7) In addition to silybin, silymarin also contains “around 20% silychristin, 10% silydianin, 5% isosilybin and between 10 and 30% of a typically unidentified organic polymer fraction formed from the above compounds. Additionally, a minor fraction of other flavanols including 2,3-dehydrosilybin (DHSB), quercetin, taxifolin, kaempferol, and others is present.” (8) Together, all these substances make silymarin an appealing ingredient in natural health supplements.
However, do not confuse milk thistle with a similar plant known as blessed thistle (Cnicus benedictus). Whereas milk thistle is used primarily for liver health support, blessed thistle is recommended as a galactagogue to promote lactation in breastfeeding mothers. (9, 10)
A Brief History of Silymarin
Silymarin, as milk thistle seed extract, was used medicinally as far back as Ancient Egypt, with the plant artistically represented on everyday objects. It was also referenced in the Bible (when it was called Lebanon cardus) and by Roman naturalist Pliny the Elder (23–79 A.D.), when it was used to treat snake bites, depression, and toxicity. (11) In ancient texts, milk thistle is also sometimes called Our Lady’s Thistle, because according to traditional religious teachings, the milk-white veins on the leaves originated from the milk of the Virgin after falling upon the plant. (12) Greeks and Romans also used milk thistle to support liver health and eliminate toxins from the body, which is what the plant is primarily still used for today. (13)
However, in the 17th-century, Nicholas Culpeper, a British herbalist and botanist, recommended taking an infusion of the fresh root and seeds of milk thistle (silymarin) to open the obstructions of the liver and spleen, support against symptoms of jaundice, and break and expel toxins from the body. He also recommended eating the plant as a blood cleanser. (14, 15) After removing the prickles, the young shoots and leaves of the milk thistle were boiled and eaten similar to boiled cabbage, or baked into pies, while the flower heads were boiled and prepared like artichoke. Pigs would eat the leaves as well, and goldfinches would consume the raw seeds. (16) Other historic uses of silymarin were as a natural remedy for upper gastrointestinal tract and digestive issues, menstrual disorders, and varicose veins. (17)
Today, milk thistle and its seed extract of silymarin are used in many different herbal remedies and dietary supplements.
Potential Health Benefits of Silymarin
According to research, the antioxidant and anti-inflammatory properties of the silymarin extracts from milk thistle seeds may have farther-reaching potential benefits than previously expected. It is believed that silymarin may help maintain healthy cholesterol and blood sugar levels already in the normal range; protect the immune system; support healthy-looking skin and cells by fighting oxidative damage from free radicals; protect against estrogen deficiency-induced bone loss; promote a healthy weight; protect against upper respiratory airway inflammation and fluid in the lungs, which could be helpful for people with allergies or asthma; and support healthy brain function during the aging process. (18)
While that’s quite a long list, the main consensus regarding the potential health benefits of silymarin focus on its ability to support healthy liver function.
Silymarin May Support Healthy Liver Function
The liver is one of the largest organs in the body, located on the right side of your belly under the ribs. This important organ is used in all metabolic processes. Its main role is to convert nutrients from foods we eat into substances the body can use for various bodily functions. By breaking down fats and proteins, the liver produces energy for the body. By breaking down carbohydrates, the liver helps maintain healthy blood sugar levels already in the normal range. The liver also helps break down damaged blood cells and produces the proteins used in blood clots. (19)
When toxins build up in the body, you may experience fatigue, chronic allergies, headaches, or neurological dysfunction. The liver helps to detoxify and filter free radicals from the blood, flushing out toxins into bile, a product of the gallbladder, which the body eliminates through the kidneys or bowels.
Chronic liver disease (cirrhosis), occurs when scar tissue has replaced healthy liver tissue, slowing the flow of blood through the liver and impacting its ability to function. The most common causes are hepatitis, obesity, high cholesterol, high blood pressure, and alcohol abuse. Chronic liver disease may eventually lead to liver failure. (20) Fortunately, experimental studies have demonstrated the antifibrotic, antioxidant, and metabolic effects of silybin, which makes it a promising herbal-based option for people with chronic liver disease. (21) “Milk thistle extract [also known as silymarin] may protect the cells of the liver by blocking the entrance of harmful toxins and helping remove these toxins from the liver cells.” (22)
According to experimental and clinical trials, silymarin may have a beneficial effect on the health of people with chronic liver diseases caused by oxidative stress. Specifically, “silymarin exerts membrane-stabilizing and antioxidant activity, it promotes hepatocyte regeneration; furthermore it reduces the inflammatory reaction and inhibits the fibrogenesis in the liver.” In addition, “silymarin can significantly reduce tumor cell proliferation, angiogenesis, as well as insulin resistance.” (23)
Studies on rats have shown that silymarin may increase protein synthesis and healing within injured liver cells. When dried, milk thistle contains 1.5-3% of silymarin, an active compound extracted from the plant’s seeds that have antioxidant properties, helping to protect cells and DNA from oxidative damage caused by free radicals (from aging, environmental toxins, and other factors). (24)
In addition, silybin, the main active component of silymarin as stated earlier, has been reported to have a direct antiviral effect and is believed to reduce lipid peroxidation and necrosis of the cells in people with chronic liver disease. However, there are no definitive results yet. (25)
Other Potential Benefits of Silymarin
Currently, additional studies are being conducted to examine the potential benefit of silymarin on not just the liver, but also on the heart, skin, bones, and more.
When it comes to heart health, silybin has the most potential effect, but “other, minor components of the extract have also been shown to possess an important cardioprotective activity.” (26)
When it comes to healthy-looking skin, an animal study found that silymarin may have an inhibitory effect on inflammatory skin disorders when used topically. (27) In another study, oral supplementation of 210 mg per day of silymarin for a minimum of 8 weeks resulted in a 53% reduction in total lesion counts in people with chronic skin inflammation. (28) A separate study on free radical damage on skin found that herbs like milk thistle and chamomile exhibit antioxidant capabilities that may support healthy aging of the skin. (29)
A natural part of aging in addition to changes in the skin is the loss of bone density, especially among women. When it comes to bone loss, one study on postmenopausal mice found that a 10 mg oral dosage of silymarin-rich milk thistle extract over 8 weeks suppressed bone loss, providing osteoprotective effects that may be helpful in aging human women as well who may be experiencing the onset of osteoporosis (low bone mass) after menopause. (30)Other studies suggest silymarin may be beneficial to the immune system and in some instances of poisoning. According to one study, milk thistle seed extract (as silymarin) had a positive effect on the immune system. (31) In a clinical trial on animals, dosages of 420-600 mg of silymarin were used to help treat lethal mushroom poisoning, but further studies are needed on human subjects before drawing any conclusions. (32)
Challenges with Silymarin
Silymarin and silybin have poor bioavailability and low solubility in water, which means they are not easily absorbed by the intestines. Silymarin absorption rates vary between 20-50%. The bioavailability of silybin by itself is slightly higher, as the substance represents about 50-70% of the entire silymarin extract. However, research shows that a complex of silymarin, phosphatidylcholine, and new silibinin glyco-conjugates (gluco, manno, galacto, and lacto-conjugates), may improve overall solubility in water and absorption. (33, 34)
Side effects of milk thistle and its active components in silymarin may cause diarrhea, nausea, bloating, gas, and upset stomach. Women who are breastfeeding or pregnant should not use milk thistle, as it may have an effect similar to estrogen. Do not take milk thistle, silymarin, or silybin if you have an allergy to ragweed or related plants. (35)
How to Buy Silymarin
The U.S. Food and Drug Administration does not regulate herbal supplements for safety or quality, so it is important to shop for silymarin and related products from trusted stores and brands. Fortunately for consumers, all of the more than 18,000 natural health products sold by Natural Healthy Concepts have been vetted for high-quality manufacturing and ingredient standards by a certified nutritionist and a well-trained staff. (36) If you’re looking for silymarin supplements, NHC is an ideal place to start browsing to find the best options for your unique health needs. However, you should always consult with your healthcare provider first before adding any herbal supplements to your health regimen.
Silymarin and its main active compound, silybin, are generally well-tolerated by most people. However, there are no standard silymarin formulations or dosage recommendations except on individual products. According to research, a typical adult dosage is around 280-420 mg per day of milk thistle seed extract (standardized to contain 70-80% of silymarin) up to three times a day for 6-8 weeks. (37) To support liver health, specifically, a dosage of “420-600 mg of silymarin per day from an herbal extract of milk thistle standardized to 80% silymarin content” is recommended for 8-12 weeks. Or, for minor detoxification support, drink a tea of 12-15 grams of milk thistle dried fruits. (38) Try a silymarin supplement today and see if it makes a difference to your health!