An Ancient Herb

The great Greek herbalist Dioscorides cataloged milk thistle in his list of healing plants effective for liver ailments, for improving bile flow and for stimulating digestion. The Roman author Pliny was of a similar opinion. Native to the Mediterranean region, Asia Minor and southeastern Russia, the milk thistle is now extensively cultivated as a healing herb.

Although it is distinctive with its prickly leaves and milky sap, the milk thistle (Silybum marinum) nevertheless is sometimes confused in popular works with a quite different plant known as blessed or holy thistle (Cnicus benedictus). This herbs is so popular in Germany that it is grown to a limited extent in the north of that country despite the fact that this is outside of its natural range.

Today, milk thistle extracts are among the most popular and the best researched of all herbal remedies in the Western tradition. Therefore, it is a bit surprising to learn that this herb had largely become forgotten by the middle of the 20th Century.

The United States Dispensatory of 1947 barely mentioned the herb extract for a brief paragraph devoted mostly to its historical aspects. The most common folk use of the plant outside of Central Europe was to improve lactation.

Modern research, beginning in the 1960s, has focused on the typical German employment for complaints on having to do with bile disorders and liver dysfunctions. German scientists at that point produced an extract called silymarin which was found to have a variety of potent liver-protectant properties.

The active principles, however, constitute only 1 to 4% of fruits of the milk thistle, and this is one reason that it is necessary to highly concentrate the extract in order to provide benefits. Jarrow Formulas^® Silymarin 80% provides just such a potent extract concentrate.

Special Antioxidant Benefits

Silymarin refers to the most active three components of milk thistle. These components are known as flavonoids and consist primarily of silybin mixed with smaller amounts of silydianin and silychristin. This trio neutralizes toxins and is known to help regenerate damaged livers and to improve liver function.

Moreover, silymarin can take over many of the detoxification functions of the liver itself. There is considerable evidence that the actions of the extract primarily rest upon its ability to inhibit the production are the actions of hepatotoxic compounds (liver toxic compounds). Silymarin does this in part by preventing free radical generation and damage.

The liver is the primary organ of detoxification. Many toxins are either themselves free radicals or they encourage the production of free radicals. These toxins somehow prevent the liver from employing its built-in defenses against free radicals.

Silymarin both intervenes in the generation of free radicals in the liver and also breaks the cycle itself by acting as a potent antioxidant. In fact, silymarin in some measurement systems is ten times more effective than is Vitamin E in preventing unwanted oxidation and free radical generation. However, this is not the end of the story.

Milk thistle extract increases the liver's content of the antioxidant enzyme glutathione (GSH)  by roughly 35% while at the same time increasing the levels of the body's other major antioxidant enzyme, superoxide dismutase (SOD). A third way in which silymarin prevents free radical damage is by inhibiting the actions of the enzyme catalyst known as lipoxygenase in the liver.

Lipoxygenase acts upon polyunsaturated fatty acids to produce pro-inflammatory compounds called leukotrienes. Leukotrienes also are involved in damage to the membranes of liver cells.

Silymarin is active against all of these types of assaults upon liver cell integrity and function. It therefore can be said to provide direct antioxidant benefits and also indirect benefits through the elevation of the levels of the body's own antioxidant enzymes and the inhibition of the generation of pro-inflammatory compounds, such as leukotrienes.

Supporting Liver Regeneration, Bile Solubility

Several studies have indicated that silymarin has a stimulatory effects upon the synthesis of protein in the liver. This is important because the liver is the only organ which is capable of extensive self-regeneration. It can markedly increase the renewal of its cells in order to produce an abundance of new cells to replace those which have been damaged. Silymarin's effect of supporting cell renewal appears to be entirely limited to healthy tissues; malignant liver cell growth is not encouraged by silymarin.

Milk thistle classically is associated with digestion and bile production. These are important functions of the liver and their impairment can lead to a negative feedback loop involving the organ. Clinical trials ave supported this traditional employment of the herb. The extract can increase the solubility of the bile, and therefore reduce the tendency toward stone formation.

Bio-availability

There is broad agreement among researchers that silymarin exhibits such poor solubility in water that delivery in the form of teas provides less than 10% of the activity of the source material. Similarly, the older studies which demonstrated the efficacy of silymarin as a cholagogic (bile flow-inducing) always used alcoholic tinctures rather than the water-based and other non alcoholic liquids now often sold.

In addition to its poor solubility, only 20-50% of silymarin is assimilated from the gastrointestinal tract. These facts would seem to make it obvious that an orally effective milk thistle supplement needs to be highly concentrated. Jarrow Formulas^® Silymarin 80% is just such a highly concentrated source. the German Commission E monograph covering the use of milk thistle suggests that 200-400 mg silymarin is the equivalent of 12-15 grams of the crude herbal extract. This is the amount of concentrated silymarin delivered by 3 capsules of Jarrow Formulas^® Silymarin 80%.

Source: Jarrow Formulas

View our Selection of Products

Scientific References

Deak G, et al. [Immunomodulator effect of silymarin therapy in chronic alcoholic liver disease]. Orv Hetil. 1990 Jun 17; 131(24): 1291-2, 1295-6.

Lang I, et al. Effect of the natural bioflavonoid antioxidant silymarin on superoxide dismutase (SOD) activity and expression in vitro. Biotechnol Ther. 1993; 4(3-4): 263-70.

Muzes, G. et al. [Effect of silymarin (Legalon) therapy on the antioxidant defense mechanism and lipid peroxidation in alcoholic liver disease (double blind protocol)]. Orv Hetil. 1990 Apr 22; 131(16): 863-6.

Sonnenbichler J,  et al. Stimulatory effects of silybin and silychristin from the milk thistle Silybum marinum on kidney cells. J Pharmacol Exp Ther. 1999 Sep; 290(3): 1375-83.

Sonnenbichler J, et al. Stimulatory effect of silybin on the DNA synthesis in partially hepatectomized rat livers: non-response in hepatoma and other malign cell lines. Biochem Pharmacol. 1986 Feb 1; 35(3): 538-41.

Sonnenbichler J, Zetl I. Biochemical effects of the flavonolignane silybin on RNA, protein and DNA synthesis in rat livers. Prog Clin Biol Res. 1986; 213: 319-31.

Tyler VE. The Honest Herbal. (Pharmaceutical Products Press, 3rd Edition, 1993) 209-210.

Wagner H. Antihepatotoxic flavonoids, in Plant Flavonoids in Biology and Medicine, eds. Cody V, Middleton E, Harboune JB (Alan R. Liss, 1986) 545-558.

Wichtl M. Cardui mariae fructus, in Herbal Drugs and Phytopharmaceuticals, ed. Bisset NG. (Medpharm / CRC Press, 1994) 121-123.