"Kava was shown in the clinical trials to be exceptionally safe. There was no major adverse event, and especially no hint to hepatic adverse events in 14,114 patients and healthy subjects exposed to kava preparations. The observation of gamma-glutamyl transaminase (GGT) and alkaline phosphatase (AP) elevations reported in heavy kava drinkers (Cairney et al., 2003a, 2003b) does not count as hepatotoxicity, as firstly a high percentage of the non-kava drinkers also showed elevations, and secondly the indicators of hepatotoxicity, i.e., the transaminases alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were not elevated. Overall, the safety profile deducible from clinical studies is benign and certainly does not confirm a hepatic risk."
Thomsen M, Schmidt M. Health policy versus kava (Piper methysticum): Anxiolytic efficacy may be instrumental in restoring the reputation of a major South Pacific crop. J Ethnopharmacol. 2020 Nov 12:113582. doi: 10.1016/j.jep.2020.113582. Epub ahead of print. PMID: 33189846.
Thomsen M, Schmidt M. Health policy versus kava (Piper methysticum): Anxiolytic efficacy may be instrumental in restoring the reputation of a major South Pacific crop. J Ethnopharmacol. 2020 Nov 12:113582. doi: 10.1016/j.jep.2020.113582. Epub ahead of print. PMID: 33189846.