With over $95 million in sales in the last year alone, milk thistle has become a consumer favorite among the natural health sector.

Milk thistle, the native Mediterranean flowering plant related to the common daisy, gets its name from the white splashes of color along with the “milky sap” that is produces. 

Consisting of a spiny orb and sharp green leaves, the thistle flower is usually bright purple when in bloom. Species name, Silybum marianu, it is the most traditional of the thistle family and has the most health benefits—such as cleansing the liver and helping boost good cholesterol levels—by making an extract from the active ingredient silymarin found within the seeds of the plant.

While silymarin is what you are looking for in the milk thistle supplement bottles at your local health food store; it seems that you may not be getting all that you are expecting in that little white bottle.

A large research company called Consumer Lab took an in-depth look at the contents of ten popular milk thistle supplements in order to find out whether or not they actually contain the recommended FDA-approved amount of silymarin.

Two of the ten products were subsequently discontinued from research because they failed to provide accurate information on what part of the plant was used in their product as well as inconsistencies in the amount of milligrams were contained in each serving.

Milk thistle has come back into popularity recently due to reports that the people suffering from diseases of the liver can benefit from the supplement and the possibility of a positive influence on preventing or stabilizing type-2 diabetes; both of which have not been 100 percent confirmed.

Milk thistle traditionally has been used as a way to naturally protect the liver and help it detoxify and is still recommended as a precautionary supplement today.

Consumer Lab reports that most of the milk thistle supplements they tested did not contain the amount of silymarin that was advertised or recommended.

The problem, however, may lie in the distribution of two distinct (one is more expensive) grades of silymarin. The Vice President of Research at Consumer Lab, Dr. William Obermeyer, thinks that this distinction may be the cause of altered levels of silymarin that are not actually in the supplement because the lower-grade silymarin is passed by a test that flies under the radar of the FDA. Consumer Lab and other legitimate pharmaceutical labs tend to use the specific HPLC (high performance liquid chromatography) method to test the safety and accuracy of the purported components inside supplements and extracts.

Both of these grades of silymarin are supposed to be 80 percent silymarin but because of the way they are tested, the less expensive one seems to be 80 percent but is actually much lower (between 47 and 67 percent, according to Consumer Lab’s report).

The worst part is that the purchasers of these supplements will not be able to tell which silymarin they are getting.

Unfortunately, because consumers cannot tell the difference, there is no foolproof way to filter out the lower-quality silymarin when looking for the ultimate milk thistle supplement for your liver-cleansing needs.

However, Consumer Lab did find one company’s supplement that passed their high standard of testing and contained the actual 80 percent silymarin extract: Jarrow Formulas Milk Thistle.

If there is this much label confusion in a lesser-known supplement like milk thistle, it peaks curiosity for the hundreds of other highly-touted supplements America is blindly ingesting.