131
Writing prior to the FDA warning, Fugh-Berman and Cott cited seven studies of kava,
demonstrating its beneficial effects on anxiety and stress, and emphasizing the German
health system’s approval of its use for that purpose, since withdrawn because of the
concern about liver toxicity. Fugh-Berman has withdrawn her recommendation as well.
After citing conflicting meta-analyses by Pittler & Ernst (2000) and Connor, Payne &
Davidson (2006), Brown et al. conclude that: "Kava has modest benefits in short-term
studies of mild anxiety. [But]Considering the risks of intoxication, the risk of abuse,
and rarely severe adverse effects, the authors do not recommend kava, until more
compelling data on safety and efficacy become available."^1 Brown et al. II concur. Thus,
as of 2013 , adequate data are not available to show safety and efficacy.
Lake and Spiegel (through Lee, Yee & Naing) confirmed moderate efficacy in the
treatment of [mild] anxiety, primarily based on Pittler and Ernst’s two meta-analyses,
and added that the reports of liver toxicity, though severe, remain very rare (2 in 250
million doses, and both using large dosages), and benzodiazepines have a far higher
rate of adverse event reports.
Mischoulon and Rosenbaum^2 give a more comprehensive critique of the kava studies,
all but two of which involved double-blind, placebo-controlled, randomized clinical trials
using a passive placebo. Only two reported studies compared kava to an active therapy.
Kava was shown in “more than a dozen” passive placebo studies to be effective with
good tolerability for treatment of “generalized anxiety, tension, agitation,
agoraphobia, specific [other] phobias, generalized anxiety disorder, adjustment
disorder, and insomnia.”^3 These studies used sample sizes of between 20 and 141
people, for a duration of four to eight weeks (although some studies went on for three
to six months), at a dosage of 150 to 400 mg. per day.
The studies that have compared kava with standard anxiolytics and antidepressants in
the treatment of anxiety showed that kava had equivalent effects to buspirone (Buspar),
opipramol (Insidon, Pramolan, Ensidon, Oprimol), and venlafaxine (Effexor, Efexor), at
manufacturers’ recommended dosages.^4