Hoodia


 

Hoodia Gordonii Clinical Report Summary

Hoodia has been used as an appetite suppressant by African hunters for 30,000 years. Scientists have confirmed Hoodia's appetite suppressing efficacy in lab tests and animal studies (1, 2, 3, 4, 5). Researchers believe that Hoodia works with brain chemicals to stop hunger cravings (1). The majority of published clinical tests have shown Hoodia to be reasonably safe: however, these studies are small and few in number (1, 2, 3). Other supportive human studies have also been conducted as well by private companies (4, 5). Researchers say more studies need to be conducted on Hoodia and its extracts to prove further efficacy and safety (1).

 

Hoodia Gordonii Overview

 

Hoodia is a succulent plant native to the desert regions of southern Africa including the countries of Namibia, Angola, Botswana and South Africa. There are many Hoodia species, but the most noted is Hoodia gordonii, which has been used by ancient people for its anorectic, appetite suppressing, abilities for more than 30,000 years. The common folklore behind Hoodia is that it has been used by the ancient San bushmen of South Africa to curb thirst and hunger when on long hunting trips across the Kalahari Desert. The San have also used Hoodia to enhance libido and reduce stomach acid: however, these uses have not been tested by modern science. The plant looks hardy but is very difficult to grow outside the Kalahari Desert as Hoodia is sensitive to specific amounts of sun, water and temperature. Because of this, the United States Fish and Wildlife Service require a permit or certificate to bring Hoodia into the United States for authencity. Modern scientists did not unlock the weight loss secrets of Hoodia until the 1990's. The stems or whole aerial part of the spiny plant are typically dried and eaten as food or processed into a supplement. Just why and how Hoodia works is still a bit of a mystery but researchers think molecules in the plant called sterol glycosides signal to the brain that the body is nourished and sated. Scientists in South Africa isolated a specific sterol glycoside from Hoodia they say is responsible for appetite suppression and called it P57 (1).

 

Safe Use of Hoodia Gordonii

 

Hoodia seems to be safe, according to years of historical use. Research studies also show Hoodia to be safe but there are only a handful of studies on record. More research needs to be conducted to determine the long-term safety of Hoodia.

Hoodia Clinical Studies

To date, very few clinical studies have been completed on Hoodia. But it seems many trials are ongoing at this time because of the promising results of existing studies. Research published in scholarly journals tested the plant in vitro and with animals as subjects. Scientists have focused on proving the folkloric use of the San Bushmen: Hoodia is an anorectic, appetite suppressant that works by effecting brain chemistry.

 

1. Hoodia and Appetite

 

As stated before, research of Hoodia as an appetite suppressant began in South Africa during the 1960's. But a clinical study was not published on the subject until 2002 when researchers presented their findings at the Experimental Biology conference in New Orleans. There, scientists explained that free-feeding rats given Hoodia cut back on the amount they ate by 50%. This was true for lean and obese rats included in the trial. In addition, the rats lost weight and had lower blood sugar after treatment (2). The entire study abstract is presented as follows:

Effects of Hoodia Plant on Food Intake and Body Weight in Lean and Obese LA/Ntul//-cp Rats. Tulp et al.

Consumption of the S. African Hoodia plant has been used for many years to control appetite in humans. To determine the effects of Hoodia sp. on food intake (FI) and body weight (BW), groups of young adult male lean and obese LA/Ntul//-cp rats were administered a dehydrated crude homogenized preparation obtained from each of 4 sp. of Hoodia or fed normally (controls). Rats were randomly assigned to treatment or control group (n=4 rats/group) and fed normally or fed crude Hoodia as an aqueous slurry, or given semi-purified extracts from equivalent amounts of the crude homogenate. Spontaneous (FI) decreased by < 50% within 2h of administration of crude plant mixture extract. Ad libitum administration (< 3 w.) resulted in sustained decrease in voluntary FI in lean and obese rats and with marked reduction in BW (<100g/rat) in obese and moderate reduction (<50 g/rat) in lean rats, while control rats fed normally gained BW normally. After 5 d treatment, total FI was similar (50+5g/rat) in both lean and obese phenotypes. Hoodia induced appetite was associated with modest decreases in blood glucose (BG) and rectal body temperature (BT) in both phenotypes, while decreases in BG and BT of pair fed rats > Hoodia treated. The ED50 for appetite suppression in a 4 h feeding test ranged from 1.8 to 2.7 g/kgBW/rat for the various sp. and were similar in both lean and obese phenotypes. The appetite suppression was associated with the organic phase of the extract. This is the first report of Hoodia sp. on appetite suppression. The physiological mechanism(s) through which the active principle(s) may mediate FI remain unknown, but may occur at least in part via hypothalamic mechanisms. These results indicate that Hoodia sp. may have a strong potential for clinical appetite regulation and weight control. Supported by Nutrisystem.com and Institutional Resources (2). 

 

2. Hoodia and Brain Chemistry

 

Researchers at Brown Medical School decided to test the theory that Hoodia changes eating habits by altering chemistry in the brain's hypothalamus. The hypothalamus is the area of the brain responsible for appetite and other functions. The P57 extract of Hoodia was injected into the brains of rats and, once again, the rats voluntarily ate less food. Researchers also found an increase of a chemical called ATP in the hypothalamus. Adenosine triphosphate, ATP, transfers energy, or food, between cells. This finding led the researchers to conclude that Hoodia seems to mimic food in its production of ATP. And ATP may be a key trigger in the brain that shuts down the urge to continue eating (3). More details of this study can be found in the abstract as follows:

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. MacLean et al.

A steroidal glycoside with anorectic activity in animals, termed P57AS3 (P57), was isolated from Hoodia gordonii and found to have homologies to the steroidal core of cardiac glycosides. Intracerebroventricular (i.c.v.) injections of the purified P57AS3 demonstrated that the compound has a likely central (CNS) mechanism of action. There is no evidence of P57AS3 binding to or altering activity of known receptors or proteins, including Na/K-ATPase, the putative target of cardiac glycosides. The studies demonstrated that the compound increases the content of ATP by 50-150% in hypothalamic neurons. In addition, third ventricle (i.c.v.) administration of P57, which reduces subsequent 24-h food intake by 40-60%, also increases ATP content in hypothalamic slice punches removed at 24 h following the i.c.v. injections. In related studies, in pair fed rats fed a low calorie diet for 4 days, the content of ATP in the hypothalami of control i.c.v. injected animals fell by 30-50%, which was blocked by i.c.v. injections of P57AS3. With growing evidence of metabolic or nutrient-sensing by the hypothalamus, ATP may be a common currency of energy sensing, which in turn may trigger the appropriate neural, endocrine and appetitive responses as similar to other fundamental hypothalamic homeostatic centers for temperature and osmolarity (3).

 

3. Other Hoodia Studies

 

As stated before, no studies of Hoodia on human beings have been published in scholarly journals. However, some researchers have conducted promising human trials and selectively released portions of their results. Most of this research has been conducted by private companies involved in the commercialization of Hoodia weight loss products. Although the results have not been peer reviewed by other doctors and scientist, it is still noteworthy to mention the ongoing research of Hoodia extracts. Here is a summary of two recent studies by private companies:

In 2001, a British pharmaceutical company says it completed a double-blind random trial with 18 male volunteers. Nine of the overweight men were given the Hoodia extract P57 and the other 8 were given placebo. Participants were allowed to eat freely, not required to exercise and treated for 15 days. The company reported that the P57 group reduced its daily calorie intake by as much as 1,000 calories, according to some reports. And it also claims that P57 participants lost body fat compared to the placebo group (1,4).

In 2004, an American doctor reported results of a study involving 7 overweight volunteers. The participants were instructed to eat a balanced breakfast, take a multi-vitamin and two Hoodia supplements a day for 28 days. At the end of the month, the doctor said participants lost an average amount of 10 pounds over the course of treatment (5).   

 

Hoodia References

 

  1. Holt S, Taylor T. Hoodia gordonii: And overview of Biological Characteristics: Part I. Townsend Letter. November 2006; 104-113.
  2. Tulp OL, Harbi NA. Dermarderosian A: Effects of Hoodia plant of weight loss and body weight in lean and obese LA/Ntul//-cp rats. FASEB J. 2002; 16(4): A648.
  3. MacLean DB, Lu-Guang L. Increased ATP Content/production in the hypothalamus may signal for energy-sensing of satiety; studies of the aorectic mechanism of a plant steroidal glycoside. Brain Research. 2004: 1020: 1-11.
  4. Successful completion of proof of principle clinical study for P57 for obesity. Phytopharm news release 2001: available at http://www.phytopharm.co.uk/hoodia_faq.html
  5. Goldfarb R. Miller D. Hoodia Gordonii (DEX-L10 Certified) and appetite suppressant: positive effect on weight loss - a case study report of 7 participants. 2004: available at: http://www.hoodiadexl10.com/clinical_study.html.
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