Efficacy of Hoodia gordonii Extract as a Weight Loss Supplement: A Comparative Study Between an Invertebrate, Tenebrio molitor (Coleoptera: Tenebrionidae), and a Vertebrate, Rattus norvegicus (Rodentia: Muridae)

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ABSTRACT

Despite legal constraints, Hoodia gordonii is marketed in many over-the-counter forms claiming to promote weight loss by reducing appetite. The belief that this plant is an efficacious appetite suppressant is based in traditional knowledge from the San tribes of the Namibian desert. We tested the efficacy of one commercial form of this plant extract to reduce feeding behavior, and therefore promote weight loss, in two different organisms. We used Sprague-Dawley rats, Rattus norvegicus, as a human analog to predict the usefulness of this plant as a dietary supplement for humans. We also used the adult mealworm beetle, Tenebrio molitor, to compare an invertebrate species with the vertebrate results. T. molitor is a close relative of many beetle species native to the same region in which H. gordonii naturally grows. The control group contained organisms not exposed to H. gordonii. The experimental group received a body mass equivalent dosage of H. gordonii in solution with distilled water for a month. We monitored food consumption and body weight for one month to compare the control group results with those of the organisms that ingested H. gordonii solution. This study does not provide support that the commercial plant product used is efficacious as a hunger suppressing dietary supplement in either species.

INTRODUCTION

Hoodia gordonii is a desert grown plant native to South Africa and the Namib Desert that has been utilized for generations by the San people of South Africa for its supposed ability to suppress hunger. This plant has recently been exploited and processed into a highly popular diet strategy marketed and sold in a variety of forms through multiple providers (Consumer Reports on Health, 2006). In 2003, an economical and legally binding arrangement was reached between the San tribes and the Council for Scientific and Industrial Research (CSIR) of South Africa, which allows these parties to monitor and control the production and sale of any products containing H. gordonii in an effort to pre vent over-exploitation of this resource (WHO, 2006). This treaty also gave the San people rights to a portion of the profit and royalties associated with the production and sale of H. gordonii-containing products (Vermeylen, 2007). With an emphasis placed on the maintenance of sufficient population levels, strict regulations have...