80% of Milk Thistle Supplements Fail Tests of Quality

Most Found to Be Low in Key Component
White Plains, New York, July 5, 2016 — Milk thistle supplements naturally contain silymarin compounds which may be helpful in certain liver diseases as well as type 2 diabetes. However, recent tests revealed that eight of ten milk thistle supplements contained much less silymarin than claimed or expected.

Most milk thistle supplements claim that 80% of their extracts are silymarin -- similar to products used in many clinical trials. But found that among five milk thistle extract supplements claiming to provide 80% silymarin, amounts actually ranged between just 51.7% to 60.4% silymarin. Three other milk thistle supplements which were tested did not list their amount of silymarin but failed to meet minimum standards. The supplements were also tested for contamination with the heavy metals lead, cadmium and arsenic. 

In its new review, explains that the high failure rate may be due to milk thistle which is being certified by manufacturers using methods which are not specific to silymarin and can inflate numbers -- unlike the validated USP method employed by

Among products which were Approved for quality, further identified those which represent the best value, providing the expected amount of silymarin at the lowest cost.'s Milk Thistle Supplements Review is now available online at The report summarizes the clinical evidence regarding the use of milk thistle, including differences between forms (extracts and herb powders), dosage, what to look for on labels, how to use milk thistle, and potential side-effects. Tests and comparisons are included for the following 12 products (including two products tested through CL's voluntary Quality Certification Program): 21st Century Milk Thistle Extract, Bluebonnet Herbals Milk Thistle, Country Life Milk Thistle Extract, Doctor's Best Milk Thistle, Douglas Laboratories Milk Thistle Max-V, Enzymatic Therapy Super Milk Thistle, Gaia Herbs Milk Thistle Seed, GNC Herbal Plus Milk Thistle, GNC Preventive Nutrition Liver Health Formula, Jarrow Formulas Milk Thistle, Swanson Full Spectrum Milk Thistle, and Trunature (Costco) Milk Thistle.

Founded in 1999, is a leading provider of consumer information and independent evaluations of products that affect health and nutrition. Membership to is available online and provides immediate access to reviews of more than 1,000 products from over 400 brands. 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.