The authors concluded that herbal medicines that contained ephedra, Cissus quadrangularis, gingseng, bitter melon and zingiber were effective in management of obesity. In light of the unclear quality of the included studies, the absence of statistical data and the small numbers of studies for each intervention, the authors' conclusions should be treated with extreme caution.

To assess the efficacy and safety of herbal medicines in the management of obesity. The review included studies of animals and humans; this abstract reports data from the studies of humans.

PubMed, Scopus, Google Scholar, Web of Science and IranMedex were searched up to December 2008. Search terms were reported.

Studies were eligible for inclusion if they investigated the impact of herbal medicines (defined as raw or refined products derived from plants or parts of plants) on obesity in humans. Outcome measures eligible for inclusion were: body weight; fat mass/fat weight; visceral adipose tissue weight; triceps skin fold thickness; waist or hip circumference; appetite; or amount of food intake. Studies on other relevant diseases were eligible for inclusion if they reported on eligible outcomes. In vitro studies, review articles, letters to the editor and unpublished articles were excluded.

Human studies were of a wide variety of herbal medicines either alone or in combination with a weight loss regime or diet administered and compared to placebo, weight loss programme, diet or supplement. The duration of the intervention was between four weeks and nine months, where stated. Participants were healthy, overweight, obese or impaired glucose tolerant volunteers. Five studies were of women only.

The authors did not state that they assessed validity.

The authors did not state how data were extracted for the review

The studies were combined in a narrative synthesis.

Nineteen studies were included for the review (n=at least 617): 17 randomised controlled trials (n=at least 507) and two before-after clinical trials (n=110).

Body weight significantly decreased with Cissus quadrangularis (CQ), Irvingia gabonensis, Garcinia atroviridis, a compound of Sambucus nigra and Asparagus officinalis, bofutsushosan, Slimax and compounds that contained caffeine and ephedra. Body fat significantly decreased with Cissus quadrangularis, bofutsushosan, Garcinia atroviridis, a compound of capsicum and lipotropic nutrients and a compound that contained caffeine and ephedra. Waist and hip circumferences significantly decreased with Slimax, Caralluma fimbriata and Cissus quadrangularis.

Adverse effects noted were loose bowel movements with Bofutsushosan and dry mouth, insomnia, nervousness, palpitations and headaches with compounds that contained caffeine and ephedra.

Findings for other outcomes were reported in the review. There was only one study for each intervention except for caffeine and ephedra where there were two or three studies for each outcome.

Herbal medicines that contained ephedra, Cissus quadrangularis, gingseng, bitter melon and zingiber were effective in the management of obesity.

The inclusion criteria were clearly stated for outcomes, broad for participants and intervention and not stated for study design. Several relevant databases were searched, but no Chinese databases included in the search; therefore, some relevant data may have been missed. Unpublished data were excluded, so publication bias could not be ruled out. It was unclear whether language restrictions were applied, so language bias could not be ruled out. Appropriate steps were taken to minimise reviewer error and bias at the study selection stage; it was unclear whether similar steps were taken for data extraction. No validity assessment appeared to have been performed and so it was not possible to determine the quality of the included studies. There was a high level of clinical heterogeneity between studies, which made the decision to combine the studies in a narrative synthesis appropriate. The absence of statistical data made it difficult for the reader to ascertain the clinical or statistical significance of the results for themself. In light of the unclear quality of the included studies, the absence of statistical data and the small numbers of studies for each intervention, the authors' conclusions should be treated with extreme caution.

Practice: The authors did not state any implications for practice.

Research: The authors stated that further research was needed to isolate and characterise the constituents of herbal compounds.

Not stated.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.