Herbal remedies are widely used by the U.S. population in the form of
over-the-counter dietary supplements. Dr. Chihiro Morishima of the
University of Washington will review regulatory and potential safety issues
associated with these products, as well as the potential for future drug
discovery.
Morishima will also share recent
research results on silymarin, derived from the milk thistle plant and used
by many individuals with chronic liver disease.
Milk Thistle/Hepatitis C Hour Video
Milk Thistle The Hep C Miracle Herb?
By Lucinda K Porter, RN
Milk thistle, Silybum marianum, is the most commonly used herb for
liver problems. One of the most frequently asked questions regarding chronic
hepatitis C viral (HCV) infection is about the use of this herb. Patients
ask me what I think of it, whether it is safe, how much they should take,
and which brand they should buy.
The answers to these questions are not simple. Before I reply to these
questions, I want to explain why this is a difficult subject on which to
state an opinion.
Traditionally, indigenous practitioners have used herbs as medicine. Anyone
can buy milk thistle without a prescription. When using milk thistle, which
part of plant is used, when is it harvested, and how is it processed?
Botanicals are not made in a lab setting. This means that the consistency of
the product is at risk. When a consumer is faced with dozens of products,
how does one know what to choose?
The Food and Drug Administration (FDA) does not regulate herbs. Drugs, on
the other hand, undergo years of rigorous testing on animals and humans
before the FDA allows them to be marketed. There is very little independent
research, although there are some good animal studies. Randomized,
controlled, double blind placebo controlled studies, the gold standard, is
virtually non-existent in the area of botanical remedies, let alone the use
of milk thistle and HCV.
It is nearly impossible to find peer-reviewed research on this subject.
Since there are no good dose studies on milk thistle, how does one know what
amount to take? That said, you might think I am not in favor of botanicals.
Actually I have a great respect for herbs and supplements. Many of our most
effective drugs use plant by-products. Centuries of herbal practice must
certainly have produced some sound observations.
I do, however, apply the same thorough standards to herbs as I do to drugs.
I am cautious with what goes through my liver, whether it is food, an herb,
a supplement, or a drug. Herbs and supplements can be powerful. As with any
medication, please be certain your care practitioner is aware of what you
are taking or plan to take. Since herbs can vary in strength and purity, it
may be wise to take a standardized and certified form. The German Commission
E is the world’s leading authority on herbs, and herb carrying this label
meets their high standards. The American Herbal Pharmacopoeia is developing
standardization guidelines for the American marketplace.
Tips:
Before you take an herb or supplement,
find out if it is compatible with the other drugs or supplements you are
taking. Verify that the supplement is not contraindicated for any other
condition you may have (see A Warning about Milk Thistle following this
article).
Tell your doctor all the herbs and
supplements you take, even if you think your doctor might disapprove.
Nurses and doctors are becoming increasingly aware of herbs.
Obtain herbs from a trustworthy source.
There have been reports of contaminated herbs.
Choose milk thistle that is
standardized.
Buy products that submit to voluntary
self-regulation.
Do not be swayed by bargain prices.
Herbs are not all equal.
Check the expiration date on the
container.
Follow the label’s dosage
recommendations. More is not better.
Herbs and supplements should not be
given to children or taken by pregnant or nursing women without a
physician’s approval.
Do I think it is safe? If you take the
suggested dose, are not on one of the medications listed at the end of this
article, do not have a complicated health problem, and buy a respected
brand, then milk thistle is probably safe. How much should you take? I
haven’t the slightest idea. I follow the manufacture’s guidelines on the
label. Which brands are the best? Here I am even less certain. The April
2001 issue of Consumer Reports On Health carried an excellent article on
liver disease. One of the sidebars discussed milk thistle. Basically, the
article found what I have found - very little reliable research on which to
make any recommendations. The medical consultants for the Consumers Union
did state the following:
Patients should not use milk thistle to replace a conventional treatment for
viral hepatitis;
Patients should not take milk thistle while on a conventional treatment for
viral hepatitis;
Milk thistle is probably safe and no one should be discouraged from taking
it if there are no other options;
Choose a brand that contains silibin and phosphotidyl choline, which may be
better absorbed.
I tried to find the research that would support the Consumers Union point. I
was unable to find solid research that supported the superiority of silibin
and phosphotidyl choline. In fact, some of the larger German studies used
thisilyn. However, I was willing to take their advice based on their
reputation.
Armed with these recommendations along with my own, I went to the largest
health food store in my area. I wanted to find a product that had silibin
and phosphotidyl choline without a mixture of other substances. I wanted the
product to carry one of the more well-known “seals of approval,” such as the
German Commission E or the National Formulary seal. The milk thistle and
liver herbs were lined up on 3 shelves. I read the labels of each and found
nothing that met my basic requirements. When I dropped the phosphotidyl
choline criterion, I found numerous choices. I have been working on this
article for months, hoping to form a neatly wrapped conclusion. I wanted to
provide a list of reliable products. Unfortunately, my research prevents me
from doing this at this time. I have stopped taking milk thistle myself
since I take one of the drugs mentioned in the A Warning about Milk Thistle
article. Until I see more convincing research, I prefer to take as little of
anything as possible.
The following article appeared on the Internet. Although it was written for
an HIV audience, the potential significance of the information cannot be
overlooked. Interestingly, Alan Francicus of the HCVAdvocate stated that
when he included this article on www.hcvadvocate.org, the number of “hits”
has been huge.
A Warning About Milk Thistle and Drug Interactions
The seeds of the milk thistle plant are commonly used to protect the liver
from damage caused by hepatitis viruses as well as alcohol and other
substances. Compounds found in milk thistle - sylibin, sylimarin - act as
antioxidants and also stimulate the repair of the liver. But now it appears
that these and possibly other compounds in milk thistle can have other
effects.
Researchers at the University of Pittsburgh have suspected that milk thistle
can slow down or reduce the activity of enzymes in the liver. What does this
have to do with HIV? you might ask. Well, enzymes in the liver break down
many of the substances that we eat and drink, including medications. If the
activity of these enzymes are reduced, then drugs remain in the blood longer
than they otherwise might. This could lead to having higher-than-expected
levels of drugs in the body, causing side effects or intensifying
already-existing side effects.
Indeed, in recent experiments using milk thistle and human liver cells, the
researchers found that relatively small concentrations of milk thistle did
significantly slow down the activity of the liver enzyme CYP3A4 by 50% to
100%. Many medications taken by people with HIV/AIDS (PHAs) - such as
protease inhibitors and non-nukes - are processed by this liver enzyme.
If milk thistle is taken by someone using protease inhibitors or non-nukes,
it has the potential to raise levels of these drugs, causing unpleasant or
even dangerous side effects.
Below is a short list of some other medications that are processed through
the CYP3A4 enzyme. Levels of these medications may increase if taken by
people who are also using milk thistle. This list is not exhaustive:
Milk thistle also has the potential to
lower levels of the following drugs:
anti-parasite drugs - Mepron (atovaquone)
sedatives/sleeping pills - Ativan (lorazepam)
hormones - estrogen
The research by the scientists in
Pittsburgh should emphasize to readers that simply because a product is
“natural” it does not mean it is safe when taken with other substances. This
research also shows the need to conduct further research on herb-drug
interactions on liver cells as well as in people. Such studies may find
combinations of herbs and drugs that can be safely used together. The
Pittsburgh researchers noted that “patients and health care professionals
must be encouraged to discuss the use of herbs and be educated about the
potential interactions between herbs and drugs.” This cannot be stressed
enough.
Reference:Venkataramanan R,
Ramachandran V, Komoroski BJ, et al. Milk thistle, a herbal supplement,
decreases the activity of CYP3A4 and uridine diphosphoglucuronosyl
transferase in human hepatocyte cultures. Drug Metabolism and Disposition
2000;28(11):1270-1273.
Milk Thistle The Hep C Miracle Herb?