By Sandra Nomoto
Despite a Decade’s Worth of Research and Marketing, the Science Remains Inconclusive on the Appetite-Suppressing Mechanism Behind Hoodia
Hoodia (Hoodia gordonii) is a succulent also known as Bushman’s hat and Kalahari cactus, because it grows in the Kalahari Desert of southern and southeastern Africa. Its flowers have a putrid smell, and are pollinated mainly by flies.
Traditionally, hoodia was chewed by the Khoi-San (San) or “Bushmen,” the oldest inhabitants of Africa, to stave off hunger and thirst during long hunts; local tribes continue its usage to survive starvation.
In 1998—two years after the Council for Scientific and Industrial Research (CSIR) had patented P57, an extract of hoodia—UK-based Phytopharm was granted a patent license from CSIR to isolate, extract, and synthesize P57, which was thought to stimulate feelings of satiety in the brain. CSIR is Africa’s leading research and development institution.
Studies and Commercialization
Hoodia’s traditional use, combined with results of a few animal studies indicating its supposed reduction of food intake, led to its development and marketing as a weight-loss supplement in the U.S. in the early 2000s.
Phytopharm sponsored several studies, two of which were never peer-reviewed or published. One study of eight obese subjects (two male, six female) taking capsules containing hoodia reported reduction of food intake, appetite, body weight, carbohydrate cravings, and a mild energizing effect. In 2004, Phytopharm collaborated with Unilever in the Netherlands to develop a functional food product, but after a reported $40 million investment, Unilever terminated the agreement in 2008 after its research concluded that P57 failed to meet the company’s high standards for safety and efficacy. By then, millions of e-mail spam messages were already sent out advertising hoodia extracts for weight loss purposes, and the U.S. Federal Trade Commission logged complaints of consumer fraud, contributing to its lack of validity.
In 2009, three companies faced lawsuits for making false claims that their diet supplements contained hoodia extract.
As there have only been a few studies done on humans, scientists have not agreed on the appetite-suppressing mechanism behind hoodia. In a randomized controlled trial done in 2011 involving 49 healthy women aged 18–50 years with a mean Body Mass Index of 25, participants were given purified extract; hoodia had no significant effect on energy intake or body weight, compared to those who took a placebo.
In 2014, a review suggested that the weight loss effects from consuming hoodia supplements may have been secondary symptoms of potentially serious adverse effects that may occur from using it.
The analytical methods developed to synthesize P57 on a large scale to develop an appetite-suppressant drug are expensive, and substantial expertise is needed to perform them. All pharmacokinetic studies completed up to this point indicated that the oral bioavailability of P57 in hoodia is low, suggesting that other molecules or metabolites may be responsible for its anti-obesity effect. Also, other glycosides have been isolated from hoodia, but scientific data is only available on P57 (“Hoodia gordonii: An Up-to-Date Review of a Commercially Important Anti-Obesity Plant,” Vermaak, Vilijoen, Hamman, 2011).
Hoodia Availability and Effects
Hoodia is available as a liquid, powder, skin cream, and patch. It may also be used in products containing other herbs or minerals, such as green tea or chromium.
Although hoodia has not been reported to affect levels of liver enzymes, it may cause increases in heart rate and blood pressure, headaches, dizziness, nausea, odd skin sensations, and vomiting. It raises bilirubin and alkaline phosphatase levels (which may indicate impaired liver function), although it has not been reported to affect levels of other liver enzymes.
It is not known whether hoodia interacts with medicines or other supplements, except for substrates of Cytochrome P450 3A4; hoodia is reported to increase its side effects.
Hoodia supplements aren’t regulated by the U.S. FDA. Experts say there aren’t enough hoodia plants in the world to account for all the alleged products on the market; some products have been found to contain little to no hoodia, include the wrong plant parts, or use questionable plant sources, so be aware of where you are shopping for them.
Moreover, the ideal dose needed to achieve weight loss or the drug’s safe upper limit is unknown. Dr. Celeste Robb-Nicholson, Editor-in-Chief of Harvard Women’s Health Watch, says that until we know more about how the hoodia products on the market work, or whether they’re safe to use, it should be avoided. If you do plan to try it, consult with a healthcare professional before use.
What is more disturbing than the inconclusive research about hoodia is that the patents on and licensing agreements for its commercialization were granted without the knowledge of the San, the originators of the plant’s knowledge. Until 2001, development continued without acknowledgement of the San, leading them to launch a long and hard challenge against the CSIR on their hoodia patent.
In November 2010, Phytopharm dropped the South African succulent from its research portfolio and returned all development and commercialization rights to CSIR. CSIR and Phytopharm were accused of biopiracy, and CSIR signed an agreement with the San people that gave them six per cent of royalties from the sale of hoodia-containing products, and eight per cent of all milestone payments that CSIR received from Phytopharm (herbalgram.org).
As hoodia is still marketed as a “quick fix” for weight loss, I would suggest a plant-based diet, which has been reported to treat Type 2 diabetes, and various other health conditions.
This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. We advise readers to always seek the advice of a physician or other qualified health provider with any questions you may have regarding a medical condition.