Tests show many milk thistle supplements low in key component — Seven products fail ConsumerLab.com testing of herb used in diabetes and liver diseases

WHITE PLAINS, NEW YORK — June 12, 2007 — Tests by ConsumerLab.com of nine milk thistle supplements that it selected showed that only two contained the expected amounts of silymarin compounds, believed to be the active constituent of milk thistle. Studies suggest silymarin may be helpful in certain liver diseases as well as type 2 diabetes. However, ConsumerLab.com found one milk thistle supplement to provide only 20% of its expected amount of silymarin, yielding as little as 1.5 milligrams of silymarin per day — much lower than the 200 to 600 mg generally recommended. Four other products provided approximately two-thirds of the expected silymarin. Another fell short by sixteen percent. A product claiming to be made under the FDA proposed GMPs (Good Manufacturing Practices) failed to list the part of milk thistle utilized (normally, the seed), violating a FDA labeling requirement.

Sales of milk thistle in the U.S. have climbed for several years, reaching $85 million in 2005 according to the latest figures from Nutrition Business Journal.

ConsumerLab.com's Vice President for Research, Dr. William Obermeyer, suggested several possible reasons for the deficiencies found among milk thistle supplements. He noted that supplement makers may rely on non-specific tests, such as UV spectrophotometric analysis, that can falsely inflate a product's silymarin content by counting compounds that are not silymarin. In contrast, ConsumerLab.com used a highly specific method, known as HPLC, in testing the products. Second, most products on the market are extracts, but poor extraction methods may leave silymarin components behind. Finally, a company looking to cut costs may simply not put in as much ingredient as promised on the label.

The Product Review of Milk Thistle Supplements can be found at www.consumerlab.com/results/milkthistle.asp and includes results for eleven products. Nine of the products were selected by ConsumerLab.com and two others are included for having passed the same evaluation through ConsumerLab.com's Voluntary Certification Program. Also listed is one product similar to one that passed but sold under a different brand name. The Review provides information on how to choose and use these supplements. Brands included in report are Designs for Health, Enzymatic Therapy, Gaia Herbs, Nature's Apothecary, Nature's Way, Planetary Formulas, Puritan's Pride, Rainbow Light, Rite Aid, Trader Darwin's, Vitamin World and Whole Foods.

Reviews of other popular types of supplements are also available online. New Reviews soon to be released include B Vitamins, Eye Health Supplements (Lutein and Zeaxanthin), Nutrition Drinks and Resveratrol (Red Wine Extract).

ConsumerLab.com is a leading provider of consumer information and independent evaluations of products that affect health and nutrition. The company is privately held and based in Westchester, New York. It has no ownership from, or interest in, companies that manufacture, distribute, or sell consumer products. ConsumerLab.com is affiliated with PharmacyChecker.com PharmacyChecker.com, an evaluator of online pharmacies. Subscription to Consumerlab.com is available online. For group subscriptions, Technical Reports, or product testing contact Lisa Sabin, Vice President for Business Development, at lisa.sabin@consumerlab.com.



— END —

back to top