Writing in the latest issue of the American Herbal Products Association (AHPA) Report, Rolf Teschke, MD, said the kava (Piper methysticum G. Forster)-related adverse events were, "most probably a consequence of poor-quality raw kava material employed in the manufacture of a few kava extracts.”
"Toxicity was associated with ingestion of traditional aqueous kava extracts, acetonic and ethanolic kava drugs, and kava dietary supplements in kava-herb mixtures. These adverse reactions emerged unexpectedly in face of the apparent safe traditional use of kava for thousands of years."
AHPA chief science officer Steven Dentali, PhD, said more research was required to determine if the cause of the issues was kava’s active constituents – predominantly kavalactones – or something else that may have arisen in the harvest, handling, and processing of the kava plant, as Teschke’s article points out.
"The connection Teschke makes between the chemical variety of kava and its intended use is rare to see in studies," Dentali said. "Not only does this review make that important point about kava use, but it also covers the host of hypothetical reasons for kava's supposed toxicity, critically evaluating each one of them, including the potential toxicity due to the possibility of mycotoxin contamination."
In his article, that is available here, Teschke draws attention to the “thousands of years” of traditional kava use, as well as improved quality measures.
"To minimize hepatotoxic risks due to kava use, efforts have to be undertaken to improve kava quality standards and to establish strict regulations for kava cultivators, farmers, harvesters, manufacturers, and physicians treating patients for anxiety, tension, and restlessness," he said.
"Novel experimental studies are required to elucidate theoretical pathogenetic
mechanism(s) underlying reported kava-associated adverse events in face of the present uncertainty of their culprit(s)," he wrote.
Dentali added: "Case reports can only serve as sentinel events. In the absence of an immediate health hazard, an understanding of the materials involved, their chemical constituents, possible mechanisms of action, and other considerations are needed to properly evaluate sentinel events before bans are implemented against potentially useful remedies."
Kava is a herb from the pepper family with a long history of use as a relaxant in the Pacific Islands, and more recently in Europe, the US and Australia as a herbal medicine and in foods such as tea, cereal products, smoothies and spirit drinks.
Kava is banned in some European countries like France, Ireland, the UK and Portugal, but remains on-sale in dietary supplement form in the US, Canada, Australia, New Zealand and many other countries.