Comments on the book: Evidence-Based Herbal Medicine, by Michael Rotblatt, MD, PharmD, and Irwin Ziment, MD, FRCP – reviewed by Steven L. Zeitzew, MD
Dr. Michael Rotblatt, generously donated a copy of his book to the Orthopaedic Learning Center. I do not intend for any critical comment I make to be unkind, or to impugn his motives. From my personal conversations with him I can tell you that he is genuinely interested in and trying to promote treatment that is in the best interest of his patients. Please accept these frank remarks as a discussion of this work, but not a criticism of the authors. The differences I have with the authors are mostly differences in philosophy. I don’t agree that weak evidence of risk justifies use based on weak evidence of efficacy. In spite of these criticisms I applaud this compilation and annotation of a considerable body of evidence to suggest that there is likely much in herbal medicine worthy of true scientific study.
As I read the book I had mixed impressions. It is well written, well organized and readable. I have strong reservations about the tone, accuracy, and style. It did not represent what I would consider a true evidence-based commentary. If used with sufficient caution it is a very convenient reference, but I would not recommend it as a guide to treatment of any patient.
The authors persuasively and effectively make the point that the evidence of risk of herbal medicines is mostly in vitro evidence, case report, and anecdote. They rightly criticize this evidence as being less convincing than in vivo evidence, such as placebo controlled double blind study. However, in most cases the evidence of efficacy is just as weak, or weaker still.
The authors make the assumption that herbal remedies are safe until it is proved otherwise, yet strongly criticize pharmaceutical drugs on the basis that some that have been FDA approved were later found to have more risk or less efficacy than previously thought. They note the “dearth of well-documented data” concerning herbal medicine, but in my opinion incorrectly argue that that dearth of evidence for risk and drug interactions is evidence of safety when it in fact represents a lack of evidence to adequately address that issue. The authors are critical of discussions of potential drug interactions based on pharmacology because of this absence of clinical data, but the burden of proof of safety and efficacy rightly should fall on those who are promoting and selling these products. The authors acknowledge that popular herbal medicines have not been well studied, but fail to suggest that they meet an FDA type standard of having evidence of safety and efficacy prior to marketing. The distortions of the risks of FDA approved drugs detracts from the credibility of their other claims. The book’s emphasis of the known risks of pharmaceuticals is not put into the perspective of risks vs. benefits, and I therefore found that portion of it misleading.
One concern I had is the lack of evidence-based commentary on efficacy of and indications for the use of herbal medicines. For many of the substances and indications discussed there is an evidence-based medical treatment available of established safety and efficacy. By not putting these herbal medicines into the context of evidence-based treatment of patients the authors missed the opportunity to provide an evidence-based guide to the herbal medicine they discuss.
emphasis is placed on what they note are problems with potency, purity, accurate
labeling, adulterations, and contaminations of current herbal medicines.
The authors make
passing uncritical remarks about claimed effects and traditional indications for
the use of herbal medicines. The tables they provide almost universally do not
address evidence, or lack of it, for these effects and claims, while information
about risks is relegated to the text and footnotes when it is present.
The positive tone
unsupported by evidence concerns me, such as the claim that herb-drug
interactions appear to be less frequent and less serious than drug-drug
Two examples help
illustrate my concerns about the tone and emphasis of the authors.
The chapter on Kava
includes note of significant adverse effects reported with its use including
those also reported last year (the year of book publication) by the FDA in its
warning about Kava and liver damage. The summary at the end of the chapter
concluded that Kava appears to be beneficial and well tolerated though rare
serious reactions may occur. The assertion of the rarity of serious reactions is
not supported by evidence.
The chapter on
Ephedra discussed case reports of serious risk, but stated “the reliability of
many of these reports is questionable”, quoting a NEJM study that attributed
only 31% of reported events as attributable to Ephedra. They do not go on to
note that the study referenced rated 31% of the reports as definitely or
probably related, another 31% as possibly related, and 21% as having
insufficient evidence to assess causation. Those that were excluded included
those for whom history or product information was incomplete as well as those
for whom there was another likely cause or the claimed effect was inconsistent
with Ephedra pharmacology. The study (but not this text) noted also that 21% of
the adverse effects definitely, probably, or possibly caused by Ephedra resulted
in death, another 26% in permanent disability, and that 19% of the serious
events occurred in those persons taking low doses and who had no important risk
factors. Of the group reported as definitely or probably caused by Ephedra at
least 27% of those who died or had permanent disability had been taking low
doses and had no important risk factors (for some the dose or risk factors were
not fully known by the reviewers). Another study not quoted by the authors noted
that nearly 2/3 of all reports (1178 of 1832) of adverse events to a poison
control center due to herbals were for Ephedra, though it represents <1% of
herbal sales. I do not find it reassuring that people without known risk factors
taking normal doses of a substance of doubtful efficacy are in fact dieing and
becoming disabled at an uncertain rate, though perhaps less frequently than some
One additional problem with giving these unproved treatments approval, is that it gives more credibility than is justified to their purveyors who often are unable to diagnose serious conditions, try to persuade patients to forgo adequate science based treatment to serious conditions, or are advocates of other complementary remedies and alternative practices that is either known to be harmful, or is simply of unproved efficacy.
I don’t agree with the authors that the “placebo effect” is an effect caused by the placebo. The term merely refers to the measured outcomes in the control group in a placebo-controlled study and implies a lack of causation, representing the natural history of the condition under study. The outcomes in the group given no treatment (sham treatment or placebo) are the true baseline; they are the outcomes that can be expected in the absence of treatment. The placebo does not cause these placebo group outcomes, however. Administration of pharmaceutically active herbals with credible evidence of risk is not equivalent to administration of placebo, an inert sham treatment, it is more dangerous. If the authors claim that the expected benefits are no greater than those that can be expected in the absence of treatment, i.e. placebo, then those risks are not justified.
Another concern I had was the lack of critical evaluation of the underlying theories and principals of some of the complementary remedies and alternative practices they discuss. The authors’ acceptance of the plausibility of homeopathy without any notation of the contradiction with basic physics and chemistry does not include a hint of the kind of extraordinary evidence of efficacy that would be required before a reasonable logical evidence-based physician would accept the magical notions of homeopathy which apparently require efficacy of a substance that is no longer present in the medication given.
subjected to objective scientific scrutiny has led to numerous useful medical
treatments in the past, and will likely continue to do so.
I recommend that the advice and treatments we offer our patients be based on scientific evidence of safety and efficacy, and that we await such evidence before making our recommendations. As a physician I can not in good conscience recommend that a patient take a substance or undergo a procedure either known to be ineffective or of uncertain efficacy and risk. In spite of my concerns, hopefully not too strongly stated, I have found it a useful reference in spite of disagreeing with the conclusions about the current place of unproved herbal medicine in the clinical setting.
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