Okay, where were we? In Part 1, I showed you how to get started looking for herb research on PubMed and American Botanical Council. In Part 2, we searched for “Silybum marianum” (or Milk Thistle) on PubMed to see if we could find any studies that describe its effect on the liver. We found one, but I ended my last post by saying that in my opinion, the study was not a good one (much to my disappointment). And in this post, I’ll explain why.
A good study is one that is able to isolate the effect of one variable (in this case, the Milk Thistle) on a particular condition (in this study, it was chronic Hepatic C). In order to do that, the study has to “control for” as many variables as possible. In other words, it has to eliminate the potential effects of other variables to be able to say, “This improvement was caused by Milk Thistle and Milk Thistle alone.”
One REALLY important variable that must be controlled for in order for the study to be considered a good study is the “placebo effect.” To control for the placebo effect, scientists will usually divide the sample into two groups: one group would get the real Milk Thistle, and the other would get, say, a sugar pill or capsule. None of the participants in the study would know which one they were getting…in fact, ALL of the participants would be led to believe that they were getting something medicinal that might help them. This way, the researchers can separate out what part of any improvement is due to there being an actual therapeutic benefit, and what part is due to the extraordinary power of the human brain to cause healing simply by believing in it so strongly. This is one of the most wonderful assets of the human brain, in my humble opinion, but alas, by not separating it out in this study, the scientists don’t really advance the cause of Milk Thistle.
How do I know they don’t control for the placebo effect? Well, it tells you, in the “Methods” section of the abstract, exactly what they did (and did not) do:
“55 patients with HCV (10 female and 45 male) with a mean age of 31.8 ± 6.4 years (10-67 years) were participated in the study. Patients received 24 weeks of silymarin (630 mg/day). Baseline virological biochemical, liver fibrosis (by a serum fibrosis markers, including YKL-40 and Hyaluronic acid), and SF-36 questionnaire were performed with biochemical tests repeated at the end of the treatment period.”
Translation: they took 55 people with chronic Hepatitis C and gave them all 630 milligrams per day of Silybum marianum (Milk Thistle) for 24 weeks. Afterwards, the scientists took blood tests and gave them all a questionnaire to complete to determine what, if any, effect the Milk Thistle had. So that means that all 55 people got the Milk Thistle, and none got a placebo. Of course, the scientists notice a great deal of improvement:
“There was statistically difference in mean of ALT (108.7 ± 86.6 vs 70.3 ± 57.7) before and after the treatment (p < 0.001). The means of AST were 99.4 ± 139.7 and 59.7 ± 64.32 before and after the treatment with statistically differences (p = 0.004). After the treatment, nine patients were found with negative HCV-RNA (p = 0.004) and statistically significant improvement in results of liver fibrosis markers were found only in fibrosis group (p = 0.015). Quality of life was improved significantly (p < 0.001).”
Translation: the results of the ALT tests taken after the trial were dramatically better than before the trial – we can be confident of that (I PROMISE I will eventually explain what statistical significance means, I just don’t have the time to do it in this post). However, we don’t know whether the huge improvement can be attributed to Milk Thistle or to the placebo effect. So, for all intents and purposes, not a great study.
As you can see, I would have to go and read through a lot of studies if I just wanted to follow the PubMed method alone – something that a busy Mom doesn’t have time to do. This is why I rely a lot on the American Botanical Council – they review the research out there for me, so that I don’t have to do it myself. I’ll show you what I mean next time – you’ll probably want to spring for a membership yourself after I’m done…which would be all to the good.