The Mediterranean regions of Europe, Middle East, and North Africa are home of one of the most popular herbal medicine for the last 2000 years: milk thistle. This annual or biennial plant belongs to the genus Silybum of the daisy family (Asteracea). There are only two known species belonging to genus Silybum: Silybum eburneum (a.k.a. silver milk thistle, ivory thistle, and elephant thistle) and Silybum marianum (a.k.a. blessed milk thistle, silymarin, Marian thistle, Mary thistle, Holy thistle, and others). S. marianum is more popular than S. eburneum and it is the one widely used in treating gallbladder and liver diseases.
Milk thistle has tall erect stem, toothed and thorny leaves, and disc-shaped pink-to-purple solitary flower heads at the stem’s end. The leaves exude milky sap when broken; hence, the name “milky thistle.” The seeds are the most valued part of milk thistle because it contains high concentration of the famous silymarin – a complex mixture of biologically active polyphenolic compounds including flavonolignans (silydianin, isosilychristin, silychristin, isosilybin A, isosilybin B, silybin A, & silybin B) and the flavonoid taxifolin. Extract of milk thistle seed contains 4-6% silymarin, and 20-35% fatty acids.
Milk thistle and silymarin are sometimes used interchangeably. Today, silymarin is a very popular medicine and food supplement. It is available in liquid extract, powder, and tablet forms. It is also mixed with other products such as coffee and energy drinks. It is widely advertised as “food” for the liver because it directly protects the liver from toxic substances.
Scientific studies have been done to assess the health benefits of silymarin. Although the results of these studies suggest beneficial effects of silymarin to the body (particularly the liver), larger and well-designed studies are needed since the previous studies were small and not carefully designed.
Health Benefits of Silymarin or Milk Thistle Extract
- Milk thistle is traditionally used as antidote for deathcap mushroom (Amanita phalloides) poisoning. It has been found in animal studies that silymarin opposes the toxic effects of the poisonous mushroom when administered within ten minutes of ingestion. If administered within 24 hours, liver damage and death is greatly reduced. There are few stories relating how milk thistle extract has saved human lives from deathcap mushroom poisoning. (Here is an example.)
- Many studies suggest that silymarin improves liver function and increases survival rate in patients with cirrhosis and chronic hepatitis. Most of the studies, however, were not well designed (e.g. small participant population) so it is hard to make real conclusions. More well-designed studies are needed to find out if silymarin is indeed helpful in patients with cirrhosis and hepatitis.
- Silymarin and other compounds in milk thistle seed extract may have anti-cancer properties. Laboratory studies show that silymarin has the ability to inhibit cancer cell division, shorten the life span of cancer cells, and reduce blood supply to tumors.
- The ability of silymarin to reduce insulin resistance in patients with type 2 diabetes and cirrhosis has also been studied by various scientists.
- Flavonoids found in milk thistle extract are powerful antioxidants which scavenge harmful free radicals – unstable and reactive compounds that damages DNA and cellular structures. Antioxidants are needed by the body to prevent cancer, diabetes, liver disease, cardiovascular disease, and other diseases.
- Results of clinical trials show that silymarin significantly reduced the harmful side effects of chemotherapy for leukemia.
Read: Milk Thistle Side Effects and Drug Interactions