Milk thistle, or silymarin, has been used as a natural herb to assist liver function for thousands of years. Well established as a liver herb in both alternative and scientific literature, milk thistle strengthens liver cell membranes, decreases "bad" cholesterol levels, boosts the immune system, and is a powerful antioxidant. Milk thistle has also been demonstrated clinically to have a positive effect on certain cancers. However, medical science continues to remain silent about milk thistle as a cancer remedy despite clinical support, according to a recent statement published by the National Cancer Institute.
Supporting science for milk thistle as a cancer remedy
Integrative Cancer Therapies published a review of several clinical trials involving milk thistle for cancer in 2007. In the review, a comment was made that "promising results" were being reported about milk thistle's ability to protect the body from certain types of cancer. The researchers stated that the future of milk thistle for cancer was, again, "promising."
In the same issue, Integrative Cancer Therapies stated that milk thistle protects the liver and kidneys from chemotherapy drug toxicity. The herb reduces liver enzyme levels, helps reduce inflammation, and assists in modulating T-cells. This study mentioned clear evidence of milk thistle's ability to fight reproductive system cancer cells in both males and females, as well as skin cancer. Milk thistle is generally accepted as safe and well-tolerated.
If the National Cancer Institute knows milk thistle works, why not say so?
The National Cancer Institute readily admits there are case studies proving the effectiveness of milk thistle for cancer. In one case study, a woman with leukemia had to stop chemotherapy because her liver enzyme levels were abnormal. When milk thistle was administered, those levels were normalized, and the woman was able to continue her cancer treatments.
In a second case, a man's liver tumors regressed before beginning chemotherapy simply by taking milk thistle.
Yet a third, placebo-controlled study involving 50 children with leukemia showed improvement over a four week period when the experimental group of children took milk thistle. Tests showed that milk thistle was able to protect the children's livers from the toxic effects of chemotherapy to the point where these children did not have to have their dosages reduced. Unfortunately, there was not enough improvement to be documented as "significant."
The National Cancer Institute goes on to mention clinical studies which support the use of milk thistle for a variety of liver diseases, hepatitis C, and diabetes. So why not say milk thistle "works?"
Revisited and reconfirmed in August 2012, the National Cancer Institute stated that it cannot recommend the use of milk thistle in cancer therapy because of a qualifying standard called "evidence scores."
An evidence analysis looks at the strength of the statistics used in any clinical study and the strength of the endpoint, or outcome of any given treatment. Combining these analyses produces an evidence score, which is assigned to every study submitted to the National Cancer Institute for review.
In the case of milk thistle, the problem lies not in the herb, but in the limited number of clinical studies. Until more well-designed research is performed, the National Cancer Institute cannot recommend milk thistle as a remedy for cancer.
Herbal Legacy.com, "Milk Thistle," by John T. McCorrie
Cancer.gov, "Changes to This Summary (08/10/12)
Pubmed.gov, Integrative Cancer Therapies. 2007 Jun;6(2):146-57. "Review of clinical trials evaluating safety and efficacy of milk thistle (Silybum marianum Gaertn.)," by C. Tamayo and S. Diamond
Pubmed.gov, Integrative Cancer Therapies. 2007 Jun;6(2):146-57. "Advances in the use of milk thistle (Silybum marianum)," by J. Post-White, et al.
Cancer.gov, "Summary of the Evidence for Milk Thistle"