Late last century the herb kava (Piper methysticum) was emerging as a serious player in the battle against anxiety. Several clinical trials had confirmed its efficacy and the experience of herbal clinicians was that it worked well in real life. But then concerns began to emerge about kava causing liver toxicity in a few users, not because it was toxic to the liver itself, but because it triggered a rare response in the immune system. This reaction caused the immune cells of some unhappy users to attack their livers, apparently resulting in severe damage in some cases.
The phenomenon is known as drug-induced liver injury (DILI) and occurs at varying frequencies for most orthodox drugs. Under political pressure over this issue, the German health authority decided to ban the therapeutic use of kava in June 2002. This was despite the fact an extensive analysis suggested that the incidence of DILI from kava use was lower than the rate with conventional sedative drugs, such as the benzodiazepines.1
Governments banned kava based on rare incidents and political pressure
One by one, the international authorities in Europe, Canada and Japan moved to stop the sale of kava products. In Australia, after careful examination of the issues by an expert committee (of which I was a member), the regulators decided to only allow traditional forms of kava, namely the root powder or a water extract of the root. Extracts made with solvents such as ethanol (alcohol) and acetone were not permitted.
This decision in Australia made sense, given its close proximity to Pacific island communities such as Fiji and Vanuatu, where kava is safely consumed in its traditional form as commonly as coffee is in the West. Banning water extracts of kava in Australia would have baffled and inconvenienced the many expatriate islanders and their descendants now calling Australia home. To them it would have been the equivalent of banning coffee because of safety concerns!
In the US, the FDA did not move to restrict the sale of kava. However, insurance companies offering liability cover to marketers of kava were spooked by all the negative publicity and raised their premiums, effectively restricting the sale of kava products on commercial grounds.
The future of kava looked bleak, with both clinicians and patients essentially denied perhaps the most effective herb in their daily battle against stress and anxiety. However, a group of scientists in Australia led by Dr. Jerome Sarris (a former research student of mine) decided to test out the efficacy and safety of a kava water (aqueous) extract. Ironically, they undertook the very first clinical trials on this ancient (and potentially safer) way of taking kava.
In clinical trial kava beat back anxiety and depression
They first confirmed that the water soluble extract of kava was effective in treating anxiety and improving mood in people with chronic anxiety in a short term placebo-controlled, double-blind, crossover trial.2,3 After one week of placebo (pre-treatment phase), 41 adults with one month or more of elevated generalised anxiety received aqueous kava extract providing 250mg/day of kavalactones or placebo tablets for one week (phase 1). Participants then swapped treatments for an additional week (phase 2).
During phase 1 HAMA (a measure of anxiety) scores dropped by an average of 9.9 points with kava, compared to a reduction of just 0.8 for the placebo. Overall, for both phases of the trial, kava significantly reduced anxiety when compared to the placebo (p<0.0001). In fact, the drop of 11.4 points over placebo on HAMA was around what we could expect with benzodiazepine drugs. Depression was also significantly reduced and no serious adverse effects were observed.
The group then followed up with a longer study. In this trial, a total of 75 people with generalised anxiety disorder (GAD), but without depression, were enrolled in a six-week, double-blind trial of an aqueous extract of kava versus placebo.4 The kava dose contained 120mg of lactones per day, but this was increased to 240mg if there was no response. Kava significantly reduced anxiety after six weeks (by 7.6 points on the HAMA scale), versus a placebo effect of 4.2 points. Interestingly, kava was most effective for those participants who had more severe anxiety. In addition, 26 per cent of people in the kava group had their anxiety brought into remission, versus only 6 per cent in the placebo group, again a significant result (p=0.004). Also in people with pure GAD and no additional anxiety disorders, the effect of kava was stronger.
Zero signs of serious side effects or liver toxicity seen in trials
In terms of safety and addiction, there were no serious adverse effects in the kava group, and certainly no signs of hepatotoxicity.5 Results on the Arizona Sexual Experience Scale (ASEX) showed that kava didn’t lead to any problems with sexual performance or enjoyment. In fact, in women there was an indication of improved sexual function with kava, including an increase in their libido! In a separate study, the Australian researchers also found that normal doses of kava aqueous extract do not impair driving ability, whereas 30mg of the drug oxazepam did.6
These positive clinical findings are great news for kava and are leading a renaissance in its use for anxiety, just as overblown fears about liver toxicity are beginning to fade away in the face of a lack of convincing new cases.
In part two of this kava article I will examine kava’s use in sleep disorders and provide a brief review of the latest thinking about its safety from experts in the field.To your better health,
Nutrition & Healing
Volume 7, Issue 10 – October 2013
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