Hoodia is a cactus-like plant that grows in the Kalahari desert in South Africa and Namibia. Advertising literature associated with hoodia claims that the herb has been used for thousands of years by the San people (commonly, though inappropriately, known as Bushmen) in order to stave off hunger and thirst during long desert treks. However, this statement has not been independently verified. Other sources state that the plant was used by the San rarely, and only as a food—in fact, as a disfavored food consumed only when better tasting food sources were not available.
In approximately 2002, hoodia began to be heavily marketed as a supplement for weight-loss. However, there is no reliable evidence that it offers any benefit.
The manufacturer Phytopharm cites a double-blind, placebo-controlled study of 18 overweight people in the UK who were given either hoodia or placebo for 15 days. Reportedly, people in the hoodia group consumed 1,000 fewer calories daily than those in the placebo group, despite remaining sedentary. This would be an enormous effect, if true. However, this study was small, it was performed by the manufacturer without outside supervision, and it has never been published. Only if a larger, independent study verifies these results will it be possible to say that there is meaningful evidence supporting the use of hoodia for weight loss.
The only published evidence on hoodia is far too preliminary to be relied upon. One animal study found that when the presumed active ingredient of hoodia is injected into the brains of rats their appetite decreases.1 The authors conclude from their research that hoodia may work by affecting metabolism in the brain. However, injections in the brain are quite a different matter from oral consumption and could suppress appetite simply by being traumatic. Potentially more meaningful animal studies compared hoodia against placebo when fed to rats.2,3 Supposedly, benefits were again seen. However, these studies were published only in abstract form, and therefore the results cannot be independently evaluated. In any case, numerous products cause weight loss in animals but do not prove to be useful treatments when tested in people.
The purported active ingredient of hoodia is a substance christened "P57." For a time, the drug company Pfizer investigated P57 as a possible weight-loss drug, but they ceased research in 2003.
MacLean, DB, Luo, LG. Increased ATP content/production in the hypothalamus may be a signal for energy-sensing of satiety: studies of the anorectic mechanism of a plant steroidal glycoside. Brain Research. 2004;1020:1-11
Tulp OL, Harbi NA, Mihalov J, DerMarderosian A. Effect of Hoodia plant on food intake and body weight in lean and obese LA/Ntul//-cp rats. FASEB J . 2001;15:A404.
Tulp OL, Harbi NA, DerMarderosian A. Effect of Hoodia plant on weight loss in congenic obese LA/Ntul//-cp rats. FASEB J. 2002;16
Last reviewed December 2015 by EBSCO CAM Review Board
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