ConsumerLabMilk Thistle

Poor quality control with milk thistle supplements

At the end of 2006 I listed milk thistle as a supplement worth additional research. This was because of a study in people with diabetes where milk thistle was associated with a decline in A1c circuclating in blood.

Now, has tested 12 milk thistle products.

7 products failed their tests.

  • 1 supplement had 20% of the expected amount of silymarin compounds — the key active components in milk thistle.
  • 4 other products provided no more than two-thirds of their expected amounts.
  • Another fell short by 16%.
  • 1 supplement failed to identify the part of milk thistle used — an FDA labeling requirement.

It makes it difficult for consumers to achieve positive results when the manufacturers fail to maintain quality control.

6/16/07 19:35 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.