Silymarin, a complex mixture of flavonolignans, is the main pharmacologically active ingredient of milk thistle, usually used in an extracted form. Milk thistle is often used to treat liver problems, and sales of supplements containing silymarin remain strong. In an estimated 30–50% of milk thistle products, the label claims of active ingredients do not hold up in the actual product, when analyzed with methods such as HPLC-UV. In some investigated samples, the active ingredient content did not even reach the minimum standard. This does not pose a direct threat to consumers’ health, however, the expected therapeutical benefits are not given in products with low content of silymarin.
- McCutcheon, A. (October 16, 2020) “Botanical Adulterants Prevention Bulletin: Adulteration of Milk Thistle (Silybum marianum)”. Botanical Adulterants Prevention Program. American Botanical Council.