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Piper methysticum
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Update on the Alleged Liver Toxicity of Kava
by Ed Smith
This article is meant to address the concerns of our readers about recent
adverse event reports (AERs) which imply than kava products may have a
toxic effect on the liver. The following will give some background and
an update on this ongoing issue.
We are still actively working with the Kava Committee of the American
Herb Products Association (AHPA) on determining what more, if anything,
needs to be done to assure the continued safe use of kava products. AHPA
has suggested adding cautionary statements to kava product labels and
many companies are doing so.
Recently AHPA commissioned Dr. Donald Waller, a pharmacologist and toxicologist,
to scientifically review and evaluate all of the kava AERs. Dr. Waller
concluded that there is "no clear evidence that the liver damage
reported in the USA and Europe was caused by the consumption of kava."
The report concludes:
".... kava when taken in appropriate doses
for reasonable periods of time has no scientifically established potential
for causing liver damage. However, as with any pharmacologically active
agent, there is always the possibility of drug interactions, preexisting
disease conditions and idiosyncratic or hypersensitivity reactions,
which can exacerbate the toxicity of such an agent."
AHPA has been meeting and working
closely with the FDA on the safety of kava products. The FDA has evaluated
the kava AERs but has not declared kava products unsafe nor taken any
actions against them. At this point kava products continue to be legally
sold in the USA.
It appears that the German Federal Institute for Drugs and Medical Devices
(BfArM)) is on the verge of making kava a controlled drug in Germany that
will be available only by prescription. However, the Commission E, a special
herb expert committee commissioned by BfArM, has issued a statement that
is critical of BfArM's conclusions and action. The Commission E recently
issued the following statement:
"When one examines the reactions in detail,
it appears that the BfArM’s classification of causality linked
to kava, is, to a large extent, incomprehensible, and arbitrary. Moreover,
in its evaluation of cases, the BfArM had not taken into consideration
various existing pieces of information, for example those with regard
to other possible causes. One extreme example may be concerning the
aforementioned lethal case: in this instance, it was known to the Institute
that the cause of liver failure was several years of alcohol abuse,
and that kava was not involved in the genesis of the liver symptoms.
The autopsy had shown that the cirrhotic process had already started
long before the administration of kava began."
A review by Schmidt and Narstadt of
eight toxicological studies on kava extracts, as well as isolated kavalactones,
showed no evidence of hepatotoxic effects.
Careful evaluation of kava AER's show that most were related to the concomitant
use of prescription drugs with potential hepatotoxic (liver toxicity)
effects, alcoholism, or other situations that raise doubts about the validity
of the kava AERs. Also, all of the kava AERs are apparently associated
with concentrated extracts of kava (30- 70% kavalactones) rather than
with raw kava root, traditional kava beverages, or kava tinctures (AKA,
liquid extracts).
Although the reports that associate kava and liver damage have not been
substantiated the following information should be considered when taking
kava products:
- A qualified healthcare professional should be consulted
before taking kava if you have or have had liver problems, frequently
use alcoholic beverages, or are taking any medication
- Stop use and see a doctor if you develop symptoms
that may signal liver problems (e.g., unexplained fatigue, abdominal
pain, loss of appetite, fever, vomiting, dark urine, pale stools, yellow
eyes or skin).
We should all take the issue of kava safety seriously
and work hard at solving any possible problems. However, while doing so
we should also consider kava's safety record. For over three thousand
years kava root has been consumed safely by millions of people in the
South Pacific islands. Also, billions of doses of kava extract have been
safely consumed by millions of people in Europe and the USA in the past
100-plus years. If, indeed, there is a liver toxicity problem with the
consumption of kava -- and that is yet to be proven -- then it appears
to be a very small and isolated problem.
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