Milk thistle has been successfully used to treat liver inflammation for centuries. Over recent years, doctors have been applying it to hepatitis conditions with varying success. Now recent research is confirming that Milk thistle's primary constituent complex, Silymarin, may indeed be helpful for liver inflammation, but its ability to treat viral hepatitis is being questioned.
Hepatitis C infection is quickly becoming an epidemic. According to Centers of Disease Control statistics, deaths from hepatitis C infections (HCV) doubled between 1999 and 2007. HCV-related deaths have now surpassed HIV-linked deaths according to the CDC. And baby boomers account for an estimated three out of four HCV infections within the U.S.
Viral hepatitis C is a leading cause of liver disease outside of cirrhosis – often caused by alcohol and/or pharmaceutical use. Hepatitis C is an infection caused by a virus communicated through sexual contact, needle sharing, blood transfusion and between mother and child. The virus has infected some 170 million people around the world, and an estimated 3.2 million people in the U.S. are infected with HCV.
Silymarin and HCV
The most convincing evidence for the treatment of hepatitis C with Silymarin was published last winter. The study comes from the Medical School of Iran's Isfahan University. The researchers treated 55 patients – 45 men and 10 women – with active and chronic cases of HCV infections with 630 milligrams a day of Silymarin for 24 weeks.
Before and after the treatment, the researchers tested the patients for ALT and AST serum amino transferases (liver enzymes), liver fibrosis, and RNA to measure their liver inflammation levels. After 24 weeks of treatment, the ALT liver enzyme levels went down from an average of 108 U/L to an average of 70, and AST levels went from an average of 99 U/L to an average of 60. Fibrosis markers were also found to be significantly decreased among those HCV patients with liver fibrosis. Quality of life scores improved significantly, and of the 55 patients treated, nine had HCV-negative RNA levels after the treatment.
The researchers concluded that, "this study indicated that in patients with CHC performing Silymarin (650 mg/day) for 6 months, improved serum HCV-RNA titer, serum amino transferases (ALT, AST), hepatic fibrosis and patient's quality of life."
While these results certainly seem promising, a more recent study, published in July's Journal of the American Medical Association (JAMA) found quite the opposite results.
This study, from the Liver Center at the University of North Carolina, Chapel Hill, conducted in four medical centers, included 154 adults with chronic hepatitis C viral infections. The study was randomized, double-blinded and placebo-controlled. It involved only those with serum alanine aminotransferase (ALT) levels above 65 U/L or more and had undergone interferon therapy without success. In other words, these were chronic, severe cases.
The patients were given either 420 milligrams of Silymarin, 700 milligrams of Silymarin, or a placebo three times per day for 24 weeks.
The researchers' protocol measured success by how many of the patients reached the normal range of ALT levels as long as the decline went down by 50%. The normal range is 45 U/L – which is a significant drop from the 65+ U/L levels – with some much higher.
The results were disappointing. There were only two people within each of the Silymarin treated groups, and two people in the placebo-group that satisfied the research protocol for success. That meant less than 4% of the Silymarin-treated patients were considered clinically improved.
However, when mean ALT levels among the treatment groups are compared, the placebo group's levels went down an average of 4.3 U/L, the 420 milligram Silymarin group's levels went down an average of 14.4 U/L, and the 700 milligram Silymarin group's levels went down by 11.3 U/L on average. This means that the liver inflammation reduction for the Silymarin groups were between two and three times that of the placebo group.
Still, their inflammation reduction was fairly low by treatment standards. The researchers concluded that, "higher than customary doses of Silymarin did not significantly reduce serum ALT levels more than placebo in participants with chronic HCV infection unsuccessfully treated with interferon-based therapy." The operator here is "significantly." This did not mean that Silymarin did not reduce ALT levels. It also does not clarify that ALT levels were lower among the 420-milligram group.
While this study certainly appraises the use of Silymarin as not very beneficial, quite contrary to the Iranian study, there are caveats to consider. It should also be noted that the Iranian study did not use a placebo, but rather simply measured enzyme levels before and after treatment, with the patients all knowing they were in the treatment group. This could have swung the results towards the positive.
Does this mean that Silymarin and thus Milk thistle is useless for hepatitis-C infections?
This was the conclusion of researchers from the University of Calgary, who published a 2005 study that reviewed the research to date on Silymarin for chronic hepatitis C and B infections. They found that while Silymarin was effective in decreasing serum transaminases (ALT and AST) in most of the research, there was little evidence showing its effectiveness in reducing viral hepatitis C and B infections.
The Big Caveats: Milk thistle constituents and their delivery
Last December a study from the University of North Carolina's Eshelman School of Pharmacy shed light on the relative differences in efficacy between liver inflammation and hepatitis-C. The researchers gave patients with either non-cirrhosis liver disease or hepatitis-C either doses of Silymarin or placebo every eight hours for a week. Every 48 hours they sampled the subjects' blood and measured circulating levels of Silymarin constituents (flavonolignans) and their conjugates.