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herbal medicines with weight loss

Insufficient evidence supporting herbal medicines with weight loss

Study analysed 54 RCT comparing the effect of herbal medicines to placebo for weight loss in over 4,000 participants, with weight differences of ≥2.5kg deemed ‘clinically significant’

There is currently insufficient evidence to recommend any of the herbal medicines for weight loss according to researchers from the University of Sydney, Australia, who conducted the first global review of herbal medicines for weight loss in 19 years.

"The problem with supplements is that unlike pharmaceutical drugs, clinical evidence is not required before they are made available to the public in supermarkets or chemists," said senior author, Dr Nick Fuller from the University of Sydney's Boden Collaboration for Obesity, Nutrition, Exercise and Eating Disorders based at its Charles Perkins Centre. Adding that with overweight and obesity rates reaching epidemic proportions worldwide, many people are turning to herbal supplements as an alternative approach to maintain or lose weight.

Herbal medicines or herbal supplements as they are commonly known, are products containing a plant or combinations of plants as the active ingredient. They come in various forms including pills, powders or liquids. Common herbal supplements used for weight loss include green tea, garcinia cambogia, white kidney bean and African mango.

The authors write that between 1996 and 2006, 1000 dietary supplements for weight loss were listed on the Australian Register of Therapeutic Goods without evaluation of efficacy. These substances can be sold and marketed to the public with sponsors (those who import, export or manufacture goods) only required to hold, but not necessarily produce, evidence substantiating their claims. The authors note that only 20 percent of new listings are audited annually to ensure they meet this requirement.

The systematic review and meta-analysis, 'Effectiveness of herbal medicines for weight loss: A systematic review and meta‐analysis of randomized controlled trials', published in Diabetes, Obesity and Metabolism, analysed the latest international research including 54 randomised controlled trials comparing the effect of herbal medicines to placebo for weight loss in over 4,000 participants, with weight differences of ≥2.5kg deemed clinically significant.

The review excluded studies where the herbal medicine did not include the whole plant, was comprised of plant oils or combined with other dietary supplements such as fibres and proteins. This analysis will be reported in a future paper.

The research team found that despite some of the herbal medicines showing statistically greater weight loss than placebo, weight loss was less than 2.5kg and therefore not of clinical significance. Indeed, they reported that only a single agent - Phaseolus vulgaris - resulted in a statistically significant weight loss compared to placebo, although this was not considered clinically significant. No effect was seen for Camellia sinensis or Garcinia cambogia. Statistically, but not clinically, significant differences were observed for combination preparations containing C. sinensis, P. vulgaris or Ephedra sinica.

Of the herbal medicines trialled in ≤3 randomised controlled trials, statistically and clinically significant weight loss compared to placebo was reported for Irvingia gabonensis, Cissus quadrangularis, and Sphaeranthus indicus combined with Garcinia mangostana, among others. But - the authors note - these findings should be interpreted cautiously because of the small number of studies, generally poor methodological quality and poor reporting of the herbal medicine interventions.

“Many of the herbal medicines meta‐analysed produced statistically significant weight loss compared to placebo, but these effects were below the level of weight loss that is considered clinically important. Some herbal medicines warrant further investigation in larger more rigorous studies to determine the effect size, dosage and long‐term safety, notably C. quadrangularis, S. indicus and I. gabonensis, and some products were only represented by one study,” the researchers concluded. “Many of the included studies were small, of poor design and methodological quality, with inadequate reporting of the herbal medicine interventions. Future RCTs would benefit from trial registration, and ensuring the study is conducted and reported in a way that minimises bias and conforms with the CONSORT Statement for reporting of clinical trials. Currently there is insufficient evidence to recommend any of these herbal medicines for weight loss.”

The most recent data on the use of weight loss supplements, from a US study, showed that among people trying to lose weight 16 percent (12 percent of men and 19 percent of women) reported past-year use.

"The growth in the industry and popularity of these products highlights the importance of conducting more robust studies on the effectiveness and safety of these supplements for weight loss," added Fuller.

To access this paper, please click here

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