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The Health Benefits of Milk Thistle

Milk Thistle

Dr. Kristie Leong

The milk thistle plant has been used as a medicinal agent for many centuries and is still a popular supplement today particularly for those who suffer from liver related disorders. But does milk thistle actually have benefit against liver related problems and can it help to protect the liver from injury? Most of all, is this popular supplement safe?

The active component of the milk thistle plant is believed to be a flavonoid component known as silymarin which is extracted from the seeds of the milk thistle plant. The milk thistle plant is grown predominantly along the Mediterranean coast although it can be found in various areas throughout the world. The young leaves of the milk thistle plant are commonly used in salads in European countries. Enthusiasm over the silymarin component of the milk thistle plant stems from small studies showing it has anti-inflammatory and antioxidant properties as well as beneficial effects on liver function. Here are some of the purported benefits of milk thistle:

Liver Protective Properties

Numerous studies have shown that milk thistle can benefit liver function in persons diagnosed with chronic liver disease although most of these studies were not well designed. Although preliminary results look promising, larger well designed studies are needed to document an established benefit. Studies directed towards patients suffering from viral or alcohol induced hepatitis have been less impressive with most studies not showing a clear benefit.


A study conducted in Iran and published in Phytotherapy Research in 2006 showed that milk thistle may help to control blood sugar levels in persons with diabetes. Unfortunately, this study was small involving only fifty-one people Several previous studies have also shown some benefit of milk thistle in helping to control blood sugar. Larger, well designed studies will be needed to confirm whether milk thistle does indeed have a documented effect on blood sugar control.

Positive Effects on Cholesterol Level

A positive benefit of milk thistle has been suggested in a variety of animal studies. The previously mentioned study published in Phytotherapy Research demonstrated a positive effect of milk thistle on total cholesterol, LDL levels, and triglyceride levels in diabetic patients tested. The subjects in this study took 200 mg. of a milk thistle supplement three times per day and were noted to have significant reductions in all three lipid levels.

Possible Cancer Protection

Some studies have shown that milk thistle can suppress the growth of human cancer cells in the prostate, breast, and cervix and may help to enhance the action of cancer chemotherapy drugs. So far, large clinical trials on humans to document these preliminary results haven’t been conducted, although preliminary results look promising.


Although there is some evidence from small studies that milk thistle can have positive effects on a variety of disease states, the association is far from proven. The most compelling benefits have been demonstrated in patients who have cirrhosis of the liver. It appears that the milk thistle supplement has a good safety profile with the most significant side effects being diarrhea and gastrointestinal upset. If you suffer from chronic liver disease, it should not be taken without a physician's clearance, but may be a safe adjunct to traditional medical therapy if used under medical guidance. As far as its use for the prevention of cancer and the control of blood glucose and cholesterol, it’s probably best to wait for further studies to confirm its effectiveness.

Health Disclaimer. Copyright ©2015. Dr. Kristie Leong is a family practice physician and medical writer. Published with permission.