About Hoodia

Botanical Information on Hoodia Gordonii

The succulent plant Hoodia Gordonii belongs to the family of plants known as Asclepiadaceae. (1-3,26-31) There are at least 2,000 species of the Asclepiadaceae group of plants, and half of these species are succulents. (1,2) The term succulent, applied to a plant, implies that the body of the plant is full of juice and has fleshy tissues that will conserve water. Breaking the skin of the plant Hoodia results in the flow of juices and presentation of "plant flesh."

Hoodia is a genus within the family of Asclepiadaceae. (32) Although a variety of species of Hoodia are found in the desert regions of Southern Africa (Kalahari, Botswana, and Namibia), not all varieties of Hoodia have been used as appetite suppressants. (1,2) The principle, prized plant of the San bushmen of Southern Africa is Hoodia Gordonii. (3)

There may be more than 20 different species of Hoodia that grow in Southern Africa. (1,2) These plants grow in short clumps with a vertical stem that is pale green in color. (1-3,26-31) Attempts to farm the species Hoodia Gordonii outside its normal habitat have been generally unsuccessful, with notable exceptions. (1,3) Hoodia plants are extremely difficult to grow, and they need a lot of care and attention, with obligatory requirements of watering, sunlight exposure, and specific seasonal temperatures. (1-3,32,33)

It is very difficult to provide a simple understanding of the botanical characteristics of Asclepiadaceae for several reasons. This family of plants shows remarkable biodiversity, but many are fly-pollinated, leafless succulents with fleshy stems that branch close to the ground. (1,2) Many of these succulent plants have small thorns, and some present different colored flowers at various times of the year. (1,2,32) Certain species of Hoodia bear fruit (Hoodia currorii), whereas some show prominent flowers that look like miniature satellite discs (Hoodia Gordonii or currorii). In addition, some Hoodia flowers look like small thorny stars (Hoodia flava). Hoodia currorii and Gordonii have purplish or reddish flowers, whereas Hoodia flava has a yellow flower. (1,2,32) In general, the flowers of Hoodia species produce a smell similar to rotten food. This scent is believed to attract insects that cross pollinate several species of Hoodia. (1,2)

There is no doubt that several species of Hoodia have been eaten for thousands of years as raw or cooked food, especially by rural inhabitants of the Northern cape of South Africa and adjacent countries. (1-3) It would appear that Hoodia is still consumed by individuals who tend animals in arable locations. (1,2) B-E. Van Wyck and N. Gericke report that shepherds of the Kalahari desert use fresh, raw Hoodia as a way of suppressing appetite and thirst. (2) These authors describe species of Hoodia as an emergency source of food and water in the harsh and dry desert environment.

The stems of Hoodia plants that have had their spines removed are the preferred portion of the Hoodia plant for eating. (1,2) Some manufacturers of dietary supplements describe the use of stems in their product, but this statement is quite inaccurate, because it is the whole aerial part of the plant that is dried for the preparation of bulk Hoodia powder. (3) Hoodia species have a bitter taste, which is quite noticeable after eating Hoodia Gordonii. (3,18)

Against this background, one may understand that there may be difficulty in identifying only one species of Hoodia during harvesting for use in dietary supplements. Of course, it is Hoodia Gordonii that has the principle, reported properties of appetite suppression. This is the species that has been the focus of most contemporary scientific research. (1-40)

The similar appearances of different species of Hoodia mean that the correct harvesting of this plant relies very much on the knowledge of local farmers or harvesters in Southern Africa. (1-3,18,28,29) It is believed that descendants of the San bushmen are the most knowledgeable concerning the identification of edible species of Hoodia. (1-3)

Hoodia species have common names that differ among different tribes of San people or San descendants. (1-3) Popular names for Hoodia species include the word "Ghaap," sometimes called khobab or Khoi. (1,2) Terminology to qualify the generic word Ghaap serves to confuse matters even further. It would appear that true or authentic Ghaap are colloquial ways of referring to Trichocaulon species of the Asclepiadaceae family of plants, whereas the word "bobbejaanghaap" is reported to be the popular word to describe Hoodia species. (1,2)

To match local terminology with botanical classification is extremely difficult. Botanical experts of the Asclepiadaceae family of plants have drawn attention to the major degree of overlap of morphological characteristics that occurs among these plants. (26,28,32) In earlier classification systems, Trichocaulon species have been distinguished from Hoodia species. (29) Professor P.V. Bruyns of the University of Cape Town (26,29) has proposed a simpler classification to unite Trichocaulon and Hoodia species under the single genus Hoodia. While this classification makes botanical sense, it confounds our understanding of the efficient identification of species of Hoodia or other Asclepiadaceae that are generally considered edible and those that are generally considered inedible. (1,2)

For the purposes of brevity and summary, Table 1 describes different types of Hoodia species which include plants that have been referred to as true or authentic Ghaap and bobbejaanghaap. (1-2) After a review of the complex botanical information on Hoodia species, one may be somewhat concerned about the quality assurance that can be placed into creating bulk powder of Hoodia Gordonii for dietary supplements, (3) without some degree of contamination by other species of Hoodia. That said, it is not generally recognized that appetite suppressant properties may occur with other Trichocaulon species, such as Hoodia currorii, in addition to Hoodia Gordonii. (1-3)

Ethnobotanical Notes on Hoodia Gordonii

There has been some inconsistency in the reports of the dietary use of Hoodia by modern San bushmen. (3,6-10) One direct quote in the media attributes the following statement to a member of the San bushmen tribe: "I learned how to eat it [Hoodia] from my forefathers ... It is my food, my water and also a medicine for me." (1-3)

The Kalahari is located near the Kgalagadi Transfrontier Park of South Africa. This desert region straddles the borders of the Republic of South Africa, Namibia, and Botswana. There are three main divisions of people within what is known overall as the "San culture." (1,2,34-40) These divisions include the Khomani, the !Xun, and the Khwe, all of whom may have used various types of Hoodia in their diet. (1,2,34-40)

While the San bushmen used Hoodia (Xhoba) for sustenance and survival, it is an alien thought to San bushmen that anyone would not want to eat. (3) The traditional use of Hoodia by the San for appetite control is an enigma. While the San were staving off their hunger with Hoodia, they may have been altering their will to eat. (3)

It is rumored that the modern San bushmen may use Hoodia for weight control when an episodic obesity occurs in tribal members who have adopted western eating habits. It is clear that any modern reports of the folklore use of any herb or botanical can be subject to variable degrees of distortion. That said, the folklore use of herbs or botanicals is a useful platform to identify new treatments for disease.

Table 1 summarizes the main species of Hoodia that are variably characterized by their ethnobotanical uses and putative therapeutic applications. It should be noted that there are other members of the Asclepiadaceae family of plants that have confusing names or even more confusing references to their inclusion under the common, colloquial term "Ghaap."

One succulent plant, referred to as Ghaap and part of the Asclepiadaceae family, is called Pectinaria maughamii. (1,2) This small plant (small Ghaap) is eaten as a fresh vegetable, and it is readily distinguished from Hoodia Gordonii in its appearance, but it has reported appetite suppressant effects. (2) Much further research is required to match ethnobotanical use of Hoodia species with common terminology used to describe many species of these plants, in order to assure a clear understanding of the best source of dried Hoodia powder for use in dietary supplements. The objective is to locate the correct species of Hoodia with biological activity for appetite suppression and other desirable actions of this plant on body structure and function, e.g., suppression of gastric acid secretion as well as energizing effects and reported aphrodisiac qualities. (3)

Research with Hoodia Gordonii

The CSIR discovered that some specific extracts of Hoodia were active at suppressing appetite.5 Researchers at the CSIR focused their attention on a group of molecules found in Hoodia that are known as sterol glycosides. (5) These molecules were of interest because of their demonstrated ability to reduce appetite in free-feeding rats. (5) The CSIR in South Africa filed a patent in 1997 on the use of these previously unidentified molecules (sterol glycosides), which could be extracted from Hoodia Gordonii. (3,5)

Biological Activity of Hoodia in Experimental Animals

In early experiments, the effect of the Hoodia plant on food intake and body weight was studied in mice and rats that were either lean or obese, based on their own genetic predispositions. (4) These experiments showed that the animals who received Hoodia had rapid onset of decreased food intake, which was sustained over a period of weeks. This resulted in major degrees of weight loss in the rats. (4)

Researchers repeated these early experiments and used a crude concentration of dried Hoodia Gordonii in "free-feeding" rats. (4,14) Again, they found marked and continuous reductions in food intake. (4,14) Obese rats lost almost twice the amount of body weight compared with lean rats. Careful measurements were made of fat distribution in these experimental animals. It was found that body fat in certain areas was reduced by a factor of 50% in both lean and obese rats, compared to similar animals on a conventional diet that did not include Hoodia. (4,14) The rats appeared to remain healthy despite their weight loss, and in separate toxicological studies, large dosages of Hoodia have been given to rats to see if any adverse reactions occur. (4,14) In these studies, large dosages of Hoodia or extracts of this plant have no obvious ill effects on rats. (4,14,41)

Researchers from Brown Medical School in Providence, Rhode Island described elegant animal experiments that show the effects of components of Hoodia on the central nervous system. (41) They expanded earlier observations by describing beneficial weight reduction and metabolic effects of Hoodia extracts (concentrates containing many components) on rats who are born to be fat and diabetic (Zucker Rats). (41) In the Zucker rats, Hoodia suppressed appetite and assisted in the reversal of diabetes, as long as the rats ate the Hoodia. (41) These fat, diabetic rats lost weight, even though they were given unlimited access to food. (4,14,41)

Extracts of Hoodia were given by injection into the head of the rat (intracranial) and directly into the brains of the rats. (41) The rats were then killed humanely, and various estimations of the chemistry of various parts of the brain were measured. In some cases, measurements were made in cultures of cells taken from specific areas of the brain, such as the hypothalamus. (41) In these experiments, the injection of Hoodia extracts into more remote areas of the brain (third ventricle) showed alterations in energy content in the hypothalamus. (41) This demonstrates the presence of many interconnecting areas of the brain that are involved in sensing the body's intake of energy (food). (41) These experiments in rats showed that Hoodia extracts could increase energy content in the nerve cells of the hypothalamus of the brain. (41) This is an area of the brain that is involved in hunger, appetite, satiety, blood pressure, hormonal, and temperature regulation. (41)

The rat studies, performed by these researchers, (41) led to their conclusion that an important mechanism of the regulation of food intake by the hypothalamus of the brain is the alteration of the contents of energy in the form of adenosine triphosphate (ATP) in the nerve cells of the hypothalamus. (41) Energy content (i.e., ATP) in these nerve cells increased by a factor of 50-150% with Hoodia administration. 41 This conclusion requires further validation, and one may question whether or not this is a complete explanation of the mechanisms of the regulation of food intake caused by Hoodia species. (3) This mechanism of action cannot explain all of the effects of Hoodia on other body functions, e.g., libido promotion or reduction of gastric acid secretion. (3)

Biological Activity of Hoodia in Humans

Scientists have performed several complex clinical studies on Hoodia Gordonii concentrates and extracts in humans. Not all of the scientific information has been reported, because much of this drug development research is proprietary, and it is being used to contribute to the pharmaceutical commercialization of the active fractions of Hoodia. (42-43)

In human experiments sponsored by Phytopharm PLC (Oxford, UK), a specific extract of Hoodia (P57) was tested for its ability to cause weight loss in free-feeding, obese volunteers. (42,43) Studies were performed in 20 obese individuals who were placed in a "metabolic unit," where detailed observations were made on food intake and other body functions. (42,43) The volunteers in this experiments were given either a "dummy pill" (placebo) or an active extract of Hoodia (P57). The volunteers were allowed to eat freely, read books, and watch TV. In other words, the subjects were able to generally lounge around without any vigorous physical activity. (43)

The individuals who received the P57 Hoodia extract (Phytopharm PLC, UK) reduced their calorie intake in their diets, of their own free will, by about 1000 calories per day. (42,43) Food was plentiful for these people and readily available, but they reduced their food intake (energy into their bodies) when Hoodia extracts were taken. (43) Many individuals lost about two kilograms in weight over a couple of weeks or so, and as a group, the people receiving Hoodia had beneficial lowering of their blood sugar and blood triglycerides. (42,43)

These results are striking and deserve much further investigation in longer-term studies with more detailed assessments of many body functions. These studies imply that components of Hoodia are active when given by mouth to humans. It is presumed that components of Hoodia reach the brain and act on energy balancing functions in the hypothalamus.

Alternative Explanations on the Mechanism of Action of Hoodia Gordonii

It is unwise to assume that the actions of Hoodia and its steroidal glycoside components on appetite regulation or feeding behavior occur only by one principle mechanism, because the controls of hunger, appetite, and satiety are extraordinarily complex. (3) Steroidal glycosides have been identified in several different plant species. (43,3) The action of this group of glycoside compounds on body structures and function remains quite under-explored in the medical sciences. (3) For example, the thistle plant (Atractylis gummifera) contains steroidal glycosides that have been defined in some medical literature as toxic components of plants. (44) The steroidal glycoside components of thistle have been called "atractylosides." (41) Thistle-derived glycosides may cause depletion of glycogen in the body. (41) Glycogen is a storage sugar that is used rapidly during any exercise. In fact, glycogen is often the first line of stored energy in the body; glycogen is used rapidly as fuel during strenuous exercise.

While steroidal glycosides in the thistle plant have a chemical structure different from those found in Hoodia Gordonii, there could be a common effect of steroidal glycosides on glycogen depletion. (3) The component of Hoodia that is believed to be a primary active component is an example of compounds called trirhabinosides. (5) The chemical name reflecting the structure of this steroidal glycoside is 14-OH, 12-tigloyl pregnane steroidal glycoside (molecular weight, 1008). (5) The molecular weight of this complicated molecule produces a size of molecule that could be well-absorbed by the gastrointestinal tract, but evidence that this molecule readily penetrates the blood brain barrier has not been presented in the medical literature. (5)

Steroidal glycosides often have a common chemical-core configuration, especially in relationship to the 14 hydroxyl (14-OH) substitution of the molecule. (5) This shared chemical configuration makes the steroidal glycosides, found in Hoodia, to be chemically similar to other glycosides found in nature, otherwise referred to as "cardenolides." (3,44)

Effects of Hoodia Unrelated to Appetite

It is known that the San Bushmen described Hoodia Gordonii as a plant with energizing, aphrodisiac, anti-dyspeptic, and other effects (Table 1). (1-3) The energizing effects of Hoodia Gordonii may be due to a temporary, perhaps even short-lived, rise in blood glucose that results from glycogen breakdown in peripherals tissues, caused by Hoodia Gordonii. (3) Thus, Hoodia Gordonii may have effects other than those occurring as direct consequences of the actions of the components of Hoodia Gordonii on the central nervous system. (3)

Any explanation of the appetite-suppressing effect of Hoodia that focuses on a single system for the control of food intake must be questioned because of the complexity of control of feeding behavior. The effects of Hoodia Gordonii or any extracts of this plant on prevailing blood levels of amino acids, glucose, or fatty acids are under-explored. (3) Such changes are relevant to the aminostatic, lipostatic, and glucostatic theories of appetite regulation. (3)

The complex systems that regulate food intake in animals are not exactly the same as those that operate in humans. This difference in regulating systems for energy balance is well-documented in genetic studies in morbidly obese humans. (45) Scientists do not fully understand how genetic material in the body acts to regulate obesity in humankind. (45) Genetic controls of hunger and appetite and associated body functions compound an understanding of the effects of appetite suppressants. (3) Could it be that San-bushmen and their relatives are genetically programmed to be more susceptible to the effects of Hoodia? (3)

Hoodia and Other Plants Communicate with the Brain

Although components of Hoodia Gordonii appear to be communicating directly with the brain when they reduce hunger and appetite, their "pathway" of communication may be less direct than the pathway of communication made by other plant-related substances, such as opioids or cannabinoids. (46) The human brain has plentiful opiod and endocannabinoid receptors. (46) In contrast, there is no evidence that the human brain has receptor sites for steroidal glycosides or that the brain uses these kinds of molecules in its own signaling systems (messenger molecules). (3)

A commonality exists among the effects of morphine (opioids), cannabinoids, and components of Hoodia Gordonii (presumed steroidal glycosides) on specific brain functions, most notably "pleasure" and "feeding" behavior. (3,46) These similarities between the overall effects of "three kinds" of plants that can "talk" to the brain raises the need for some more speculation on the mechanisms of action of plant compounds on the central nervous system. (3,46)

Hoodia Has Other Potential Benefits

It appears that one or more of the appetite-suppressing compounds present in Hoodia may be quite effective in reducing the secretion of acid by the stomach. (47) This effect of Hoodia components on acid secretions by the stomach seems to be present at higher doses of the Hoodia extract. For example, injections of specific types and dosages of Hoodia extracts into rats have been recorded to inhibit gastric acid secretion by a factor of up to 43%. (47)

In a US Patent dated December 3, 2002, researchers from the US and South Africa describe an invention where Hoodia components may have multiple benefits for digestive health by causing reductions in acid secretion by the stomach. (47) This patent describes a method of treating disease or disorders of the gastrointestinal tract using extracts of plants of the genus Hoodia or Trichocaulon or related chemical compounds. (47) This patent is congruent with the reported folklore medicinal use of Hoodia species for stomach ache or pain reminiscent of peptic ulcer (Table 1). These effects of Hoodia components on acid output from the stomach raise the possibility that they may have a use in the treatment of acid-related digestive disorders, such as reflux esophagitis, gastro-esophageal reflux, peptic ulcer, non-ulcer dyspepsia, and even damage to the linings of the upper digestive tract caused by ulcerogenic drugs (e.g., non-steroidal anti-inflammatory drugs [NSAID]). This digestive benefit of Hoodia may be a wonderful coincidence in clinical practice. Overweight people have a higher incidence of acid-related digestive upset, especially gastro esophageal reflux disease (GERD). (48) What about the idea of controlling appetite and losing weight while taking care of indigestion? (3)

Safety of Hoodia Supplements

On the one hand, no significant adverse effects of Hoodia have been reported with the use of hundreds of million unit dosages of Hoodia Gordonii in dietary supplements or in early reported experiments with extracts of steroidal glycosides. On the other hand, one cannot provide a complete safety seal for this dietary supplement in all contexts. (3)

Adverse effects from supplements require voluntary reporting. However, Hoodia has been a "food" for centuries in South Africa, without reports of problems and with expressions of confidence in its nutritional value from native South African people. (1-3) Furthermore, the South African government acknowledges Hoodia as a health food. (1-3) That said, the precedent for the safety of Hoodia in adults is quite strong. (1-3)

Dietary supplements containing Hoodia Gordonii cannot be considered safe for use in childhood, pregnancy, or in lactating females who are breast-feeding. (3) It is not known if components of Hoodia enter breast milk, and appetite suppression or other effects of Hoodia must be considered very undesirable in infants. (3)

A great concern exists with Hoodia if it is abused or used by individuals with eating disorders that promote weight loss. Individuals with distorted body images who want to induce extreme degrees of weight loss often have a disorder called anorexia nervosa with or without bulimia. (3) Anorexia nervosa is becoming more common, and it is a life-threatening disorder. Some comments have already been made in the media about the potential dangers of Hoodia use in the extreme "dieter," one with an eating disorder.

Conclusion

The commercialization of Hoodia Gordonii as a dietary supplement has created major interest. (1-48) Hoodia and its contents should not be seen as some kind of "magic bullet for weight control." Hoodia supplements contain whole aerial parts of Hoodia plants in a powdered form, most often in capsules or tablets. (3) Using Hoodia in this manner is close to the original folklore use of Hoodia by the San bushmen in South Africa. (1-3)

It has been emphasized in medical literature that the active components of Hoodia that suppress appetite are steroidal glycosides. However, other unidentified constituents of Hoodia could contribute to its biological effects, or Hoodia may act on the body by mechanisms other than those already proposed in scientific literature. (3) The sustainability of natural origins of this miracle of nature must become a priority with farming practices.

Stephen Holt MD, LLD (Hon.), FRCP (C), MRCP (UK), FACP, FACG, FACN, FACAM is Chairman, Department of Integrative Medicine, New York College of Podiatric Medicine, Harlem, New York; Thomas V. Taylor, MD, ChM, FRCS, FACG is Chairman of Academic Surgery, Saint Joseph's Hospital, Houston, Texas.

Disclosure: Dr. Stephen Holt has a financial interest in the commercial sale of Hoodia; Dr. Thomas Taylor does not.

Notes

1. Van Wyk B-E, Van Oudtshoorn B, Gericke N. Medicinal Plants of South Africa. Second Edition. Arcadia, Pretoria, South Africa: Briza Publications, 2000, reprinted 2002.
2. Van Wyk B-E, Gericke N. People's Plants, A Guide to Useful Plants of Southern Africa. Arcadia, Pretoria, South Africa: Briza Publications, 2000, 2003.
3. Holt S. Supreme Properties of Hoodia Gordonii. Little Falls, NJ:Wellness Publishing, 2005.
4. Tulp OL, Harbi N. Effect of hoodia plant on weight loss in congenic obese LA/Ntul//-cp rats. FASEB Journal. 2002;16 (4):A654.
5. Van Heerden and colleagues (licensed to commercial entities). Pharmaceutical Compositions Having Appetite Suppressant Activity, patent no. US 6,376,657 B1.
6. Foley S. Phytopharm to extend trials of obesity drug. The Independent (London). April 12, 2002; 25.
7. Appetite suppressing hoodia cactus. MedPlant. Medicinal Plants Network. Available at: http://www.source.bellanet.org/medplant/article.php?Sid=31.
8. Barnett A. In Africa the hoodia cactus keeps men alive. Now its secret is "stolen" to make us thin. The Observer. June 17, 2001. Available at: http://www.education.guardian.co.uk/print/0,2858,4205467-102275,00.html
9. Evans G. The diet secret of the desert. The Times (United Kingdom). November 19, 2002; 6.
10. Lund C. San to cash in on diet drug deal. Sunday Times (Africa). November 18, 2001. Available at: http://www.sundaytimes.co.za/2001/11/18/news/news 09.asp.
11. Marshall L. Africa's bushmen may get rich from diet-drug secret. National Geographic News. April 16, 2003. Available at: http://news.nationalgeographic.com/news/2003/04/0416 030416 San1.html.
12. Carroll R. It's green, prickly and sour, but this plant could cure obesity and save an ancient way of life. The Guardian. January 4, 2003. Available at: http://www.guardian.co.uk/medicine/story/0,11381,8516,00.html, p1 of 6.
13. Thompson G. Bushmen squeeze money from humble cactus. New York Times. April 1, 2003; A4.
14. Tulp OL, Harbi N. Effect of hoodia plant on food intake and body weight in lean and obese LA/Ntul//cp-rats. FASEB Journal. 2001; 15 (4): A404.
15. Kraft D. Bushmen, drug giant battle over royalties. Toronto Star (Canada). August 24, 2002; A18.
16. Henderson M. Cactus pricks obesity problem. The Times (UK). April 12, 2001;17.
17. Hawthorne P. The Hunter-Litigators: Southern Africa's San tribes are challenging the right of commercial interests to profit at their expense, NewBank InfoWeb, NewsBank Public Library Collection. Times International. August 6, 2001; 30.
18. Mangold T. Sampling the Kalahari cactus diet. BBC News World Edition, May 30, 2003. Available at: http://www.news.bbc.co.uk.2/hi/programmes/correspondent/2947810.stm
19. Stumner R. The pill-free fat-busting machine. The Independent (London). September 7, 2003. Advertisement
20. Cactus farmers defy the desert. Available at: http://news.bbc.co.uk/, 2002.
21. South African bushmen hail drug deal: South Africa's indigenous San peoples have signed a deal ensuring they will profit from a diet drug being developed from a plant they have used for generations. BBC Correspondent broadcast. Sunday, 1 June, 2003 at 1915 BST.
22. Goldfarb RM, Miller DJ. Hoodia Gordonii (DEX-L10 Certified) an Appetite Suppressant: Positive Effect on Weight Loss--A Case Study Report of 7 Participants, performed by Bucks County Clinical Research Inc (www.BCCRinc.com)
23. Tulp OL, Harbi, Nevin A. Hoodia species as a source of essential micronutrients. FASEB Journal. 2002;16 (4): A648.
24. Mangold T. Correspondent's Tom Mangold traveled to Africa and sampled the appetite suppressing Hoodia, a plant which may make Kalahari bushmen millionaires, BBC Television Broadcast By Tom Mangold, BBC 2 Correspondent. Available at: http://news.bbc.co.uk/, 2003.
25. Wynberg R., Rhetoric Realism and Benefit Sharing Use of Traditional Knowledge of Hoodia Species in the Development of an Appetite Suppressant, The Journal of World Intellectual Property, No. 6, Vol. 7, p. 851-876, November, 2004.
26. Bruyns PV. A revision of hoodia and lavranea. Bot. Jahrb. Syst. 1993;115:145-207 (cited by van Wyk B-E, reference 2).
27. Smith, CA. Common Names of South African Plants, Mem. Bot. Surv. S. Afr.35, 1966 (cited by van Wyk B-E, reference 2).
28. The Hoodia Plant, Botanic-Art, p.1 of 2. Available at: www.botanic-art.com/hoodia.htm.
29. Bruyns PV. New combinations in hoodia and lavrania (Asclepiadaceae--Stepelieae). S. Afr. J. Bot. 1993;59 (3): 342.
30. Bullock AA. Notes on African Asclepiadaceae 8: The generic name Hoodia. Kew Bull. 1956: 508, 1957 (cited by Bruyns, 1993)
31. Plowes DCH. A preliminary re-assessment of the genera Hoodia and Trichocaulon, Asklepios. 1992;56: 5-15 (cited by Bruyns, 1992).
32. Hoodia Gordonii: Taxonomy Source: USDA, ARS, National Genetic Resources Program. Germplasm Resources Information Network--(GRIN) [Online Database].
33. White A, Sloane BL. The Stapelieae. Second edition. Pasadena, California, 1937: (3).
34. Dutfield G. Intellectual Property Rights, Trade and Biodiversity: Seeds and Plant Varieties. Earthscan, London, 2000.
35. Convention on International Trade in Endangered Species of Wild Fauna and Flora. Amendments to Appendices I and II of CITES, Proposal to the Thirteenth Meeting of the Conference of the Parties. Bangkok, Thailand. 2-14 October 2004.
36. Smith CA. Common Names of South African Plants. Botanical Survey Memoir No. 3, Department of Agricultural Technical Services, Republic of South Africa. 1966;35.
37. Masson F., Stapelia novae: or A collection of several new species of that genus, London, 1796.
38. Lee RB, Hitchcock R, and Biesele M. Foragers to first peoples: The Kalahari San. Cultural Survival Quarterly. 2002; 26(1): 9-12. Advertisement
39. Von Koenen E. Medicinal, Poisonous, and Edible Plants in Namibia. Fourth Edition. Klaus Hess Publishers, 2001; 131.
40. Gall S. The Bushmen of Southern Africa. Slaughter of the Innocent. London: Pimlico, 2001.
41. MacLean D, Lu-Guang L. Increased ATP Content/production in the hypothalamus may be a signal for energy-sensing of society: studies of the anorectic mechanism of a plant steroidal glycoside. Brain Research. 2004; 1020: 1-11.
42. Dolfzine Online Fitness, San Bushmen Sue Pfizer: Hoodia Gordonii: Miracle Cactus or another Fly Trap? Available at: http://www.dolfzine.com/page612.htm.
43. Available at: Hoodia Gordonii fact file/Press/News http://www.phytopharm.co.uk/hoodia_faq.html.
44. Wogan GN, Marietta MA. Undesired or potentially undesirable constituents of foods, In Food Chemistry. Fennema OR (ed). New York: Marcel Dekker, 1985; 694-695.
45. Hamilton BS, Paglia D, Kwan AYM, et al. Increased obese m-RNA expression in omental fat cells from massively obese humans. Nature Med. 1995;1:953-956.
46. Nicoll RA, Alger BE. The Brian's own marijuana. Scientific American. 2004; December: 70-75.
47. Hakkin J. et al. US Patent No.: 6,488,967, inventors Hakkinen J, et al, assigned to Phytopharm PLC of Godmanchester, UK. Extracts of Hoodia or Trichocaulon species and related chemical compounds for therapy of gastrointestinal disease
48. Pandolfino JE, El-Serag HB, Zhang Q, et al. Clinical-alimentary tract, obesity: a challenge of esophagogastric junction integrity. Gastroenterology. 2006;130:639-649.

by Stephen Holt, MD and Thomas V. Taylor, MD

Table 1: A summary of the folklore and ethnobotanical characteristics of five principle species of Hoodia. The information is summarized from several literature sources. (1-3) The most informative source on the use of Hoodia is to be found in People's Plants, A Guide to Useful Plants of Southern Africa. (2) The authors are describing the folklore use of species of Hoodia and are not recommending the use of Hoodia as treatment for any disease. There are no published clinical trials on the use of Hoodia for disease prevention and treatment, with the exception of emerging evidence for the use of Hoodia Gordonii and related species of Hoodia as an appetite suppressant in drug development research or in dietary supplements. The principal therapeutic application of Hoodia is in weight control and the management of the metabolic Syndrome X. (3)

Hoodia Species	Used as "Food"	Used as Appetite Suppressant	Other Uses
H. gordonii	yes	yes	Peptic ulcer pain or functional dyspepsia?
H. currorii	yes	yes	Treatment for indigestion, hypertension, diabetes, and "stomach ache"
H. flava	yes	yes	?
H. officianalis	?	?	Treatment of pulmonary tuberculosis (TB), "stomach ache" and hemorrhoids
H. pilifera	yes	yes	Stems used in alcohol tinctures for treatment of "stomach ache," hemorrhoids, and pulmonary TB