Milk thistle seed protects the liver and restores the liver's ability to detoxify harmful substances. Used for centuries in the ancient world, milk thistle was touted by Greek and medieval physicians as a remedy for snakebites, jaundice, and other liver diseases. Its uses in Western folk medicine were versatile, and nursing mothers took milk thistle leaf to increase their milk flow. Extensive research conducted over the past 30 years shows that milk thistle seed extract is an effective treatment for cirrhosis of the liver, hepatitis, and inflammatory liver conditions.

Silymarin is a group of flavonoid-like compounds extracted from the small hard fruits (kenguil seeds) of milk thistle. The liver-protecting and liver-repairing functions of silymarin are due to two main actions: antioxidant and protein-restoring activities. The antioxidant activity of silymarin is ten times more powerful than vitamin E. Antioxidants scavenge free radicals that damage cells and cause lipid peroxidation. In lipid peroxidation, unstable free radicals attack the cell membrane. Silymarin prevents toxic and foreign substances from penetrating liver cells by stabilizing the outer membrane of liver cells. The active constituents displace toxins by binding to proteins and receptors on the cell membrane. Silymarin also stimulates protein synthesis in ribosomes so that new liver cells can grow and damaged liver cells can be replaced. Because silymarin acts mainly on the liver and kidneys, it is an effective antidote against poisonous substances that accumulate in the liver.

Native to the Mediterranean, milk thistle is now widespread in many areas, including eastern Europe, Asia, the eastern United States, and California. It grows wild in dry sunny areas with well-drained soils, but is usually cultivated in northern regions. This biennial or annual stout thistle has broad, wavy, lanceolate leaves; large, prickly, leaves marbled with white; and red-purple flowers. The stem branches at the top, reaching heights of 4 to 10 feet. The small, hard-skinned fruits are brown, spotted, and shiny. This plant is easy to grow, and it matures rapidly, usually in less than a year.

• Flowers
• Stems
• Seeds
• Leaves
• Fruits (kenguil seed or compressed achenes)

Fruit contains 1.5% to 3% silymarin (flavonolignans, consisting of 50% silybarin [silybin] and lesser amounts of isosilybin, dehydrosilybin, silydianin, silychristin); tyramine, histamine, essential oils, lipids (20% to 30%), sugars, alkaloids, saponins, mucilages, vitamins C, E, and K, flavonoids.

Milk thistle is prepared for oral use as capsules of concentrated extract of standardized dried herb (70% to 80%, or about 140 mg silymarin), and as tincture (liquid extract). There are several teas containing the standardized extract. Silymarin must be concentrated because it is poorly absorbed from the gastrointestinal tract.

• Traditional herbal actions: promotes milk production; cholagogue and choleretic (promotes bile production for obstructive liver and gallbladder disorders); hepatorestorative, galactagogue, and demulcent.
• Clinical applications: for chronic liver and gallbladder disorders such as cirrhosis, damage from harmful chemicals and alcohol abuse, cholangitis, pericholangitis, gallstones, and chronic hepatitis B, C, D, E, and as a supportive in acute hepatitis A; for topical use in skin conditions such as psoriasis, eczema, aging skin, erythema, burns, wounds, and sores.

Milk thistle extract (silymarin) has a liver-protecting effect against toxic chemicals (carbon tetrachloride, galactosamine, praseodymium, thioacetamide, acetaminophen). It is the most important antidote in modern medicine to poisoning from deathcap mushroom (Amanita phalloides). Milk thistle extract is so effective that it counteracts Amanita toxins even if it is taken 10 minutes after mushrooms are consumed.

Silymarin has antioxidant effects in both in vitro and in vivo studies. Glutathione is an antioxidant that helps the liver detoxify harmful chemicals, drugs, and hormones. Silymarin keeps glutathione levels from dropping too low, and in healthy humans it raises glutathione levels in the liver by as much as 35%.

In several experiments, silymarin protected against ulcers and gastrointestinal problems, relieved allergies by blocking histamine release, and decreased the activity of tumor-promoting agents. Silymarin also increased the movement of human polymorphonuclear leukocytes (PML's) blocked by harmful substances. And a silymarin-phospholipid complex had anti-inflammatory activity.

In humans, milk thistle seed extract improved fatty liver caused by chemical and alcohol damage. And in several double-blind, placebo-controlled studies, milk thistle extract improved liver dysfunction in patients with hepatitis B, chronic alcoholic liver disease, alcohol-induced liver disease, chronic exposure to organophosphates, toxic liver disorders, and chronic hepatitis. Silymarin also lowered the death rate of alcoholic patients compared to controls over a two to four year period, and it reduced the symptoms of hepatitis (abdominal upset, decreased appetite, fatigue). Silymarin increased serum bilirubin levels and liver enzymes when compared to controls, and it had a favorable effect on Type II hyperlipidemia, low platelet count, and psoriasis. Benefits of milk thistle extract have been reported for subclinical cholestasis of pregnancy, cholangitis, and pericholangitis.

• Recommended dosage: 1 to 4 g dried fruit (seeds), (200 to 400 mg silymarin)
• Protective dosage for healthy people: silymarin 120 mg bid; Tincture (1:5): 2 to 6 ml tid
• Restorative dosage for people with liver disorders: silymarin 120 mg tid. Silymarin-phosphatidylcholine complex (in 1:1 ratio) is absorbed better and has more clinical benefits than silymarin alone. (Phosphatidylcholine is a key element in cell membranes.) Decoction: 1 to 4 g of fruit in 500 ml water tid
• Recommended dosage for complex: 100 to 200 mg bid

No toxicity has been reported for long-term use in test animals (20 g/kg in mice; 1 g/kg in dogs), and long-term use does not seem to pose any danger. Milk thistle occasionally has a mild laxative effect due to increased bile flow and secretion. Dietary fiber (guar gum, psyllium oat bran, pectin) can be taken to stop loose stools and mucosal irritation.

Alcohol-based extracts are not recommended for severe liver problems.

Silybin dihemisuccinate, a water soluble form of the flavonoid silymarin (derived from milk thistle), protected rat livers from peroxidation and glutathione depletion caused by acetaminophen when it was injected intravenously (Campos et al. 1989). Liver protection was further evidenced by limited increases of aminotransaminases following toxic acetaminophen doses.

In a double-blind, placebo-controlled clinical trial, the use of silymarin with hepatotoxic psychotropic drugs (butyrophenones and phenothiazines) was evaluated (Palasciano et al. 1994). Sixty patients were enrolled in this study and were randomized into four groups of 15 to receive treatment for 90 days with either silymarin (800 mg/day) or placebo along with psychotropic drugs. Treatment with silymarin reduced serum levels of malondialdehyde, aspartate aminotransferase, and alanine aminotransferase, indicators of lipoperoxidation and hepatotoxicity. Submaximal doses of silymarin reduced the hepatotoxicity associated with treatment with butyrophenones or phenothiazines.

Silibinin (200 mg/kg IV), the main component of milk thistle extract, administered to rats one hour prior to treatment with a single injection of cisplatin (5 mg/kg) demonstrated nephroprotectant activity (Gaedeke et al. 1996). The effects of cisplatin on proteinuria and creatinine clearance were prevented completely by prior administration of silibinin. Proximal tubular functional impairment also was ameliorated. Kidney function was not affected by silbinin alone. However, concurrent administration of silibinin with cisplatin and ifosfamide significantly inhibited the anticancer effect of cisplatin and ifosfamide on human testicular cancer in vitro (Bokemeyer et al. 1996).

A rat study investigated whether silibinin treatment attenuated cyclosporin A toxicity on endocrine and exocrine pancreas (von Schonfeld et al. 1997). Rats were treated for 8 days with cyclosporin A, silibinin, or both. On day 9, endocrine and exocrine pancreatic functions were tested in vitro; blood glucose levels in vivo were higher in rats treated with cyclosporin A, while glucose levels in those treated with silibinin did not change. Insulin secretion in vitro was inhibited after treatment with silibinin, but amylase secretion was not affected. After treatment with cyclosporin A, both insulin and amylase secretion were reduced. Silibinin and cyclosporin A had additive inhibitory effects on insulin secretion, but silibinin attenuated cyclosporin A-induced inhibition of amylase secretion. Despite cyclosporin A treatment, amylase secretion was restored to normal with the highest dose of silibinin.

The U.S. FDA classifies milk thistle as a dietary supplement. In Germany, milk thistle is used as a nonprescription drug for inflammatory liver disease and cirrhosis.

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