Liver function test abnormalities in users of aqueous kava extracts

Introduction. Hepatic toxicity from manufactured herbal remedies that contain kava lactones has been reported in Europe, North America, and Australia. There is no evidence for serious liver damage in kava-using populations in Pacific Island societies or in Indigenous Australians who have used aqueous kava extracts. This article presents evidence that liver function changes in users of aqueous kava extracts appear to be reversible. Data from one Arnhem Land community [Northern Territory (NT), Australia] with 340 indigenous people older than 15 years of age in 2000 are used. Methods. This study was a cross-sectional study with 98 participants, 36 of whom had never used kava. Among 62 kava users, 23 had discontinued kava at least 1 year before the study. Continuing users had not used kava for 1 to 2 months (n = 10) or 1 to 2 weeks previously (n = 15). Some (n = 14) had used kava within the previous 24hr. Liver function tests were compared across these groups, taking into account differences due to age, sex, alcohol, and other substance use. Results. The average quantity of kava powder consumed was 118 g/week, and median duration of use was 12 years (range, 1-18 years). Kava usage levels were less than one-half of those found in previous studies. More recent kava use was independently associated with higher levels of liver enzymes gamma-glutamyl transferase (GGT) (p < 0.001) and alkaline phosphatase (ALP) (p < 0.001), but not with alanine aminotransferase or bilirubin, which were not elevated. In those who were not heavy alcohol users, only those who used kava within the previous 24 hr showed GGT levels higher than nonusers (p < 0.001), whereas higher ALP levels occurred only in those who last used kava 1 to 2 weeks (p=0.015) and 24hr previously (p=0.005). Discussion. Liver function changes in users of aqueous kava extracts at these moderate levels of consumption appear to be reversible and begin to return to baseline after 1 to 2 weeks abstinence from kava. No evidence for irreversible liver damage has been found.