Milk Thistle

Milk Thistle HCVADVOCATE.COM Newsletter
—Lucinda K. Porter, RN

People with chronic hepatitis C virus infection (HCV) who are interested in alternative medicine generally consider milk thistle (silybum marianum). This popular herb is a common ingredient in supplement blends that promote liver health. Researchers have investigated the efficacy of milk thistle and its components for a variety of conditions, including viral hepatitis, type II diabetes, cancer and toxin-removal from the liver.

The Basics
Milk thistle (Silybum marianum) is a plant from the aster family. Silymarin is the active ingredient in milk thistle that is likely responsible for its medicinal qualities. Silymarin is actually a group of flavanoids, with silybin (aka silibinin) being the most powerful. Typically, milk thistle is sold in standardized amounts of 70 to 80% silymarin.

The February 2008 issue of Hepatology looked at milk thistle use among 1145 participants in the HALT-C study, sponsored by the National Institute of Diabetes and Digestive and Kidney Disease, headed by Leonard Seeff. In this HCV study, 44% of the subjects had used herbs at some point, with 23% using them at the time of enrollment. Among all participants, milk thistle was used by 33%, 17% upon enrollment. Although milk thistle users showed similar ALT levels and HCV viral loads to non-users, they showed fewer liver-related symptoms and improved quality of life. Researchers observed that this aspect of the study was uncontrolled and that milk thistle use was self-motivated. They concluded that a well-designed prospective study can determine whether silymarin provides benefit to persons with chronic hepatitis C¹

Continue reading before you run out and buy milk thistle. All milk thistle is not alike and what is in the bottle may not match what is promised on the label. In a startling report published by ConsumerLab.com (CL), only one of 10 products passed the necessary tests in order to carry the CL seal of approval.

CL is an independent organization that provides information and testing of nutritional products. They have been around for about ten years. Some information is free, but product reports are available only to subscribers. A one year subscription is $30 and worth every penny. www.consumerlab.com

What caught my attention about the milk thistle testing is that most supplements win CLs approval. Its a voluntary program, so presumably manufacturers feel confident enough to submit to testing. The failure of nine out of ten products is extraordinary. One can only imagine the quality of products that dont agree to testing.

The Results
Two of the ten milk thistle products were disqualified for failure to meet the Food and Drug Administrations (FDA) labeling requirements. Additionally, one of these products had different dosing information from jar to jar, all from the same lot number.

Seven of the remaining eight products did not provide the standardized amount of silymarin although they all claimed to have 80%. Actual amounts were between 47 and 67%. The only product to pass was Jarrow Formulas Milk Thistle. Although the amount of silymarin was not specified on the label, the manufacturer declared that the milk thistle extract contained 80% flavonoids. The actual testing confirmed that Jarrow Formulas Milk Thistle met the minimum industry standard of 70% silymarin.

The HCV Advocate and I do not endorse particular products or treatments. However, it seemed cruel to reveal that only one in ten milk thistle products passed muster without mentioning the name of the product. However, before you run out and buy milk thistle, there are other issues.

First, why didnt the products pass? ConsumerLabs suggested it was likely due to substandard milk thistle extract, often purchased from Chinese suppliers. Unfortunately, since herbs are not strictly regulated by the FDA, it is virtually impossible to know what is safe and effective.

Second, what is the scientific evidence for or against milk thistle? Why take milk thistle? Is it because you read about it in an article? Did you hear about a study, and if so, what do you know about the research? Or did you wander into your local health food store and ask a sales clerk to recommend something good for the liver.

Third, without specific product information, do you know how much milk thistle to take, what kind, when to take it and when you shouldnt? Do you know if it interacts with other medications you may be taking? Are there any side effects? Apply the same common sense investigation to dietary supplements as you would to any medicine.

The Research
When it comes to research on dietary supplements and liver disease, milk thistle tops the list. There were 222 milk thistle listings on the U.S. Library of Medicines PubMed site dating back to 1952. Although this sounds like a lot of research, compare this to 122,853 listings back to 1957 for interferon. Although research has yet to prove the benefits of milk thistle, it has also not disproved it. This is largely due to inadequate testing or poor scientific methods.

Here are highlights of some current research:
The December 2009 issue of Gastroenterology published a French study headed by Ahmed-Belkacem, Silibinin and Related Compounds Are Direct Inhibitors of Hepatitis C Virus RNA-Dependent RNA Polymerase. They used a commercially available intravenous preparation of silibinin. This is an encouraging beginning to more research.

According to the U. S. Department of Health and Human Services Agency for Healthcare Research and Quality (AHRQ), there is evidence that milk thistle may protect the liver.² However, the research is unreliable due to poor scientific method, so its difficult to sort out the facts.

A search of Germanys independent, evidence-based Cochrane Library revealed similar observations. According to Rambaldi A, Jacobs BP, and Gluud C [There is] no evidence supporting or refuting milk thistle for alcoholic and/or hepatitis B or C virus liver diseases. Low-quality trials suggested beneficial effects. High-quality randomized clinical trials on milk thistle versus placebo are needed.³

Another problem is the test product. AHRQs website states, The largest producer of milk thistle is Madaus (Germany), which makes an extract of concentrated silymarin. However, numerous other extracts exist, and more information is needed on comparability of formulations, standardization, and bioavailability for studies of mechanisms of action and clinical trials.

If the issue isnt already complicated, consider this taken as a supplement, milk thistle is poorly absorbed. After digestion, very little is left for the liver. This is particularly true for older adults. As little as 10% of silymarin may be absorbed in the adult over age 60.

In an article in September 2009 Alternative Medicine Review, biomedical research Parris Kidd, University of California, Berkeley, notes how milk thistles most active flavonoid, silybin is poorly absorbed by the body. Kidd states, silybin-phosphatidylcholine complexed as a phytosome provides significant liver protection and enhanced bioavailability over conventional silymarin.⁴ Twenty years ago, an Italian research team reached the same conclusion based on a pharmacokinetic study of nine subjects.⁵

It all boils down to this ignoring the lack of scientific research, and choosing to take milk thistle, what product does one buy? Although the Jarrow supplement has been tested by CL, it was not used in clinical research. The one that has been used in research is the Madaus, but it is not available in the U.S. Silybin-phosphatidylcholine, used in various U.S. studies, is available. However, research grade silybin-phosphatidylcholine is not necessarily identical to consumer products.

Cautions
Talk to your medical provider before taking milk thistle, particularly if you take other drugs or supplements. Milk thistle is usually well-tolerated. It may have a laxative effect along with other gastrointestinal side effects. Allergic reaction is always a possibility, no matter what you are taking. Theoretically, milk thistle could lower blood sugar levels, so use caution if taking blood sugar-lowering medications. Exacerbation of hemochromatosis has been associated with ingestion of milk thistle.

Milk thistle should not be used by pregnant or breast-feeding women. People with a history of hormone-related cancers, including breast and uterine cancer and prostate cancer, may need to avoid milk thistle.

Since milk thistle is metabolized by the liver, it may interact with other drugs. However, despite earlier warnings about this, evidence of this is flawed. One strategy is to take milk thistle alone rather than in combination with other drugs, particularly oral contraceptives and coumadin. Milk thistle has a short half-life (4 hours).

Dosing
The following adult doses are from Natural Standard and are based on clinical research levels:

• Silymarin (Legalon) 230-600 milligrams per day divided into two to three doses
• Silipide (IdB 1016) 160-480 milligrams per day in silybin equivalents

The Bottom Line

• Talk to your medical provider before taking milk thistle.
• There is no evidence that milk thistle will eliminate HCV.
• Milk thistle may provide some benefit to the liver but research has not proved or disproved this.
• Milk thistle varies between manufacturers. Do your research before you purchase.
• Milk thistle is poorly absorbed by the body, so if you take it, choose a formulation and dose that is bioavailable.
• Alcohol extracts should be avoided by anyone with alcohol-related liver disease.

References

1. Herbal product use by persons enrolled in the hepatitis C Antiviral Long-Term Treatment Against Cirrhosis (HALT-C) Trial. Seeff LB, Curto TM, Szabo G, Everson GT, Bonkovsky HL, Dienstag JL, Shiffman ML, Lindsay KL, Lok AS, Di Bisceglie AM, Lee WM, Ghany MG. Hepatology. 2008 Feb;47(2):605-12.
2. Agency for Healthcare Research and Quality. Milk Thistle: Effects on Liver Disease and Cirrhosis and Clinical Adverse Effects. Evidence Report/Technology Assessment no. 21. Rockville, MD: Agency for Healthcare Research and Quality; 2000. 01-E024.
3. Milk thistle for alcoholic and/or hepatitis B or C virus liver diseases. Rambaldi A, Jacobs BP, Gluud C. Cochrane Database of Systematic Reviews 2007, Issue 4.
4. A review of the bioavailability and clinical efficacy of milk thistle phytosome: a silybin-phosphatidylcholine complex (Siliphos). Kidd P, Head K. Alternative Medicine Review. 2009 Sep;14(3):226-46.
5. Pharmacokinetic studies on IdB 1016, a silybin-phosphatidylcholine complex, in healthy human subjects. Barzaghi N, Crema F, Gatti G, Pifferi G, Perucca E. European Journal of Drug Metabolism and Pharmacokinetics. 1990 Oct-Dec;15(4):333-8.