Here are examination the benefits of milk thistle to lower cholesterol, treat liver problems, and benefit diabetes. Does it work? Milk thistle (silymarin) is a flowering herb related to the daisy and ragweed family. Milk thistle is also known as holy thistle, lady’s thistle, Mary thistle, Marian thistle, St. Mary thistle, silybum, and Silybum marianum. It is native to Mediterranean countries. Some people also call it Mary thistle and holy thistle. The use of milk thistle in cultural and traditional settings may differ from concepts accepted by current Western medicine. Milk thistle is available in the United States as a dietary supplement.
Milk thistle has been used medicinally since the 4th century BC. Its use in treating hepatobiliary diseases dates back to the 1700s, and its use as a liver protectant can be traced back to Greek references. Milk thistle is also used for loss of appetite, heartburn (dyspepsia), and gallbladder complaints. Some people use milk thistle for diabetes, hangover, diseases of the spleen, prostate cancer, malaria, depression, uterine complaints, increasing breast milk flow, allergy symptoms, and starting menstrual flow.The active substance in milk thistle, silymarin, is a complex mixture of flavonolignans. Silymarin’s primary constituents are the flavonolignan isomers silybins A and B, isosilybin A and B, silychristin (also known as silichristin), silydianin (also known as silidianin), and their flavonoid precursor, taxifolin. In the literature, the mixture of the silybins A and B is often referred to as silibinin.
Laboratory studies demonstrate that silymarin stabilizes cellular membranes, stimulates detoxification pathways, stimulates regeneration of liver tissue, inhibits the growth of certain cancer cell lines, exerts direct cytotoxic activity toward certain cancer cell lines, and possibly increases the efficacy of certain chemotherapy agents.
Milk Thistle Chemistry and Pharmacology
A rather complete chemical composition list of milk thistle can be found in Dr. Duke’s Phytochemical and Ethnobotanical Databases. Milk thisle seeds contain 1.5-3% flavonolignans, including choleterol, campeterol, stigmasterol, and sitosterol; and some mucilage, collectively called silymarin; 20-30% fixed oils, of which approximately 60% is linoleic acid, approximately 30% is oleic acid, and approximately 9% is palmitic acid; 25-30% protein; 0.038% tocopherol; 0.63% sterols, [Herbal Medicine – Expanded Commission E monographs, by Mark Blumenthal, Alicia Goldberg, and Josef Brinckmann, first edition, 2000]. Silymarin’s constituents are isosilybinin, silybinin, silychristin, and silydianin, of which silybinin accounts for approximately 50% of silymarin. [Dr. Duke’s Essential Herbs, by James A Duke, 1999].
Milk Thistle Benefits
- Seasonal allergies (allergic rhinitis). Some research shows that people who take a milk thistle extract in combination with a conventional antihistamine have reduced symptoms compared to people who just use an antihistamine.
- Slightly improved liver function and decreased the number of deaths in people with liver disease. Milk thistle is known to protect the liver by altering and strengthening the structure of outer cell membranes of hepatocytes (liver cells), preventing toxins from entering the liver cells, and by stimulating the regenerative ability of the liver and the formation of new hepatocytes through the activation of an enzyme nucleolar polymerase A, which leads to the increase in ribosomal protein synthesis and cell division. Milk thistle, as an anti-oxidant, may also reduce damages to liver cells caused by chronic use of certain prescription drugs. In laboratory studies, silymarin has been found to stabilize cell membranes, thus preventing toxic chemicals from entering the cell.Laboratory studies have also demonstrated that silymarin stimulates synthesis and activity of enzymes responsible for detoxification pathways.
Although these results are promising, most studies have been poorly designed. There is not enough scientific data to say whether or not milk thistle can help liver problems. Some early research suggests milk thistle may aid people with alcohol-related liver disease. Other studies show no improvement in liver function in this group of people.
- Several studies suggest possible benefits of milk thistle to treat or prevent liver damage caused by drugs, industrial toxins or toxic chemicals, such as toluene and xylene. Silymarin is most well known for its purported effects on the liver.
- Researchers have investigated the role that silibinin may play in the treatment of hepatitis and cirrhosis. Most studies have investigated the isolated compound silymarin or its most active isomer silybin, rather than the herbal plant in its whole form. Most clinical trials have investigated silymarin’s effectiveness in the treatment of patients with hepatitis, cirrhosis, or biliary disorders. These studies have employed a wide range of doses (120–560 mg /day) and have yielded conflicting results. Most clinical evidence suggests that milk thistle or specific chemicals from milk thistle do not improve liver function or reduce the risk of mortality in patients with hepatitis B and C.
- Althought Existing research shows unclear benefits for the use of milk thistle in acute viral hepatitis, or liver inflammation due to an infection from a virus. Further research is needed to draw conclusions. The most commonly reported adverse effects are a mild laxative effect and gastrointestinal upset.
- Milk thistle improved control of blood sugar in people with diabetes with and without liver disease. Some research shows that taking silymarin, a chemical found in milk thistle, along with conventional treatment can decrease blood sugar, total cholesterol, low-density lipoprotein (LDL or “bad”) cholesterol, and triglycerides in people with diabetes.
- Researchers also have found that milk thistle improved insulin resistance. Milk thistle, combined with traditional treatment, has shown a decrease in blood sugar levels and an improvement in cholesterol in people with type 2 diabetes. Although non-human research suggests cholesterol-lowering effects of milk thistle, human studies have provided mixed results. Further studies are necessary before a firm conclusion can be made.
- By lowering LDL “bad” cholesterol levels, milk thistle may help decrease the chance of developing heart disease. However, studies on possible heart benefits only have been done in people with diabetes. People with diabetes often have high cholesterol.
- An herbal preparation containing milk thistle may be effective in decreasing heartburn (dyspepsia). When used daily for 4 weeks, a specific combination product (Iberogast, Medical Futures, Inc) that contains milk thistle plus peppermint leaf, German chamomile, caraway, licorice, clown’s mustard plant, celandine, angelica, and lemon balm seems to reduce the severity of acid reflux, stomach pain, cramping, nausea, and vomiting.
- Skin damage caused by radiation treatment. Research suggests that applying a specific product (Leviaderm) containing silymarin, a certain chemical found in milk thistle, to the skin reduces skin damage caused by radiation treatment in women with breast cancer.
- Laboratory experiments and limited animal studies conducted using cancer cell lines have suggested that silibinin enhances the efficacy of cisplatin and doxorubicin against ovarian and breast cancer cells, bladder, cervical, hepatocellular, and prostate cancer. Silybin appears to have direct anticancer effects against prostate, breast, and ectocervical tumor cells. Silybin may also affect the cell cycle in cancer cells by slowing down cell growth, as demonstrated with prostate cancer cell lines. Laboratory studies using leukemia cell lines found that silybin did not stimulate growth of leukemia cells. The FDA has not approved the use of milk thistle as a treatment for cancer patients or patients with any other medical condition. Clinical trials are lacking, and use of milk thistle preparations in cancer is not recommended outside of the trial setting.
- Menopausal symptoms. Research in women suggests that taking a specific product containing milk thistle, black cohosh, dong quai, red clover, American ginseng, and chasteberry (Phyto-Female) twice daily for 3 months reduces menopausal symptoms, including hot flashes and night sweats.
Consumption of the oral form of milk thistle (standardized to 70% to 80% silymarin) at 420 mg/day in divided doses is considered safe for up to 41 months, based on clinical trial data. High-dose milk thistle has been used within the confines of clinical trials.
Milk thistle Toxicology
There are no milk thistle toxicities documented in humans, and toxicity appears to be low in laboratory animals.Acute oral toxicity of silymarin in rats, dogs, and monkeys has been estimated to be greater than 5 g/kg. Subacute toxicity studies suggest no toxicity in rats and monkeys for dosages of up to 2 g/kg for 13 weeks, and up to 1 g/kg in rats and dogs for up to 26 weeks. Investigations, including urine analysis and postmortem studies, showed no evidence of toxicity. No evidence of effect on reproduction in rats has been found, and silymarin was not mutagenic in several tests.
Milk Thistle Side Effect
- Milk thistle has not been evaluated by the FDA for safety, effectiveness, or purity. All potential risks and/or advantages of milk thistle may not be known. Additionally, there are no regulated manufacturing standards in place for these compounds.
- Although rare, allergic reactions to milk thistle have been reported. Stop taking milk thistle and seek emergency medical attention if you experience symptoms of a serious allergic reaction including difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives.
- Other less serious side effects are also uncommon and reports have included mild stomach upset.
- Use in pregnant and breast-feeding women has been reported in limited clinical studies without apparent ill-effect; however, until further data are available, avoid the use of milk thistle in pregnant or breast-feeding women.
- Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome. You may report side effects to FDA at 1-800-FDA-1088.