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Suspected black cohosh hepatotoxicity: no evidence by meta-analysis of randomized controlled clinical trials for isopropanolic black cohosh extract

Naser, Belal MD1; Schnitker, Jörg PhD2; Minkin, Mary Jane MD3; de Arriba, Susana Garcia PhD1; Nolte, Klaus-Ulrich PhD1; Osmers, Rüdiger MD4

doi: 10.1097/gme.0b013e3181fcb2a6
Original Articles

Objective: Black cohosh, a popular herbal treatment for menopausal symptoms, has been implicated in a number of hepatotoxicity case reports. The purpose of this investigation was to analyze data gained from clinical trials on the effect of black cohosh on liver function.

Methods: A meta-analysis of randomized, double-blind, and controlled clinical trials was conducted. These studies primarily evaluated the efficacy and safety of the isopropanolic black cohosh extract (iCR) in perimenopausal and postmenopausal women. Raw data on liver function values of aspartate aminotransferase, alanine aminotransferase, and γ-glutamyltranspeptidase were considered in this analysis, if these data at baseline and after 3 to 6 months of treatment were available. Standard methods of descriptive statistics were used in this analysis.

Results: Five studies involving a total of 1,117 women were included in the meta-analyses. A total of 1,020 women (test population = 517 and reference population = 503) completed the studies. Perimenopausal and postmenopausal women (40-60 y) were treated daily with iCR (corresponding to 40-128 mg drug) for 3 to 6 months. The meta-analyses of the standardized mean differences in the "test" versus "reference" showed no significant effects and no differences between double-blind, placebo-controlled and other trials. The overall fixed effect ± SEM was 0.055 ± 0.062 (P = 0.37) for aspartate aminotransferase and 0.063 ± 0.062 (P = 0.31) for alanine aminotransferase. The nonsignificant effects concerned the overall analyses of all included studies as well as the proportion of placebo-controlled studies.

Conclusions: The results of this meta-analysis of five randomized, double-blind, and controlled clinical trials showed no evidence that iCR has any adverse effect on liver function.

From 1Schaper & Brümmer GmbH & Co. KG, Salzgitter, Germany; 2Institute for Applied Statistics, Bielefeld, Germany; 3Yale University of School Medicine, New Haven, CT; and 4Hildesheim General Hospital, Department of Obstetrics and Gynaecology, Hildesheim, Germany.

Received July 5, 2010; revised and accepted September 14, 2010.

Financial disclosure/conflicts of interest: B.N., S.G.D., and K.U.N. are employees of Schaper & Brümmer GmbH & Co. KG, the manufacturer of isopropanolic black cohosh extract.

Address correspondence to: Belal Naser, MD, Schaper & Brümmer GmbH & Co. KG, Bahnhofstraße 35, D-38259 Salzgitter, Germany. E-mail:

©2011The North American Menopause Society