The Skinny on Hoodia

May 16, 2008

hoodia_weight_loss_pill.jpgCommentary by Melissa Freeman, PGY-2 

As summertime is just around the corner, many begin to evaluate whether their bodies are ready to expose what has been hidden under those bulky winter clothes. Between busy lives and an innate desire for quick results, people sometimes turn to over-the-counter diet pills for a slimmer physique. With recently banned products like Ephedra, consumers are looking for newer, more promising weight loss products. During a recent clinic visit, a patient asked me about my thoughts on diet pills that contained hoodia. Though I had never heard of this ingredient, I soon learned that hoodia has made more than a few headlines and was even featured in a segment on 60 Minutes back in 2004. Reporter Leslie Stahl traveled to Africa just to ingest the native plant.

Within the kingdom Plantae, family Apocynaceae, is a genus consisting of 13 species known as hoodia. Hoodia species are protected, cactus-like plants that naturally reside in the Deserts of South Africa. The San Bushman of the Kalahari Desert have supposedly been eating hoodia for decades to ward off hunger and thirst during nomadic herding expeditions. Now, and to their great dismay, their secret is out. Hoodia, more specifically the hoodia gordonii species, holds promise as a potential weight loss agent and many are looking to cash in on this attribute.

In the 60’s, hoodia gordonii was first studied in animals by South Africa’s National laboratory, Scientists at the Council for Scientific Research (CSIR), where they observed weight loss after the ingestion of hoodia. Soon after, CSIR joined forces with the British pharmaceutical company Phytopharm in order to isolate the active ingredient. Roughly thirty years later, they isolated an active steroidal glycoside found to be responsible for hoodia’s appetite suppression and named it p57. This p57 molecule is alleged to be similar to but significantly more powerful than glucose. Simply put, it has been found to ultimately increase the ATP content in hypothalamic neurons signaling fullness to the satiety center and thus suppressing appetite. It is also believed to suppress thirst but this mechanism has not yet been studied. Hoodia is not a stimulant and to date is without “known” reported side effects.

In 1995, the South African government patented p57 along with the application of the plant as a weight-loss agent and licensed it to Phytopharm. After a large financial investment ($20 M), Phytopharm sponsored a double-blind placebo-controlled study (2001) in obese subjects which found that those subjects in the hoodia group experienced a statistically significant decrease in caloric intake and body fat without side effects. It must be noted that this study lasted only 15 days, had an extremely small sample size, and was never actually published in a scientific journal. In 2004, an animal study published in Brain Research showed that when p57 is injected into the appetite center of rodent brains, ATP levels were altered leading to decreased appetites when compared to placebo rats.

Within the United States, both Pfizer and Unilever have shown interest in hoodia. While Unilever continues to study the plant, Pfizer pulled out of its sub-contract with Phytopharm citing that the ultimate goal of incorporating hoodia’s active compound into safe, synthetically mass-produced pills was unrealistic. Furthermore, a Pfizer researcher who studied hoodia felt that it posed possible hepatic impairment from components other than p57. Phytopharm itself realized that it was not possible to produce synthetic hoodia in large quantities and soon set up large plantations in South Africa hoping to market the plant in its natural form. While hoodia is both difficult and time-consuming to grow, those involved in the project are hopeful for the products potential success.

At present, hoodia remains questionable, endangered, and expensive. Unfortunately, hoodia is abound in multiple formulations (Hoodithin, HoodiTrim, Hoodispray, Desert Burn, HoodiaXR, and San-hoodia just to name a few) and price ranges for those looking to purchase it. Consumers are being warned that many products claim to contain hoodia when the hoodia is actually diluted, contaminated, or entirely absent. With this in mind, what is the skinny on Hoodia? Much remains to be learned about the plant, its active compounds, its efficacy, and its presumed, yet unknown side effects. While reviews thus far seem positive in terms of its ability to suppress appetite, there is no evidence to suggest hoodia’s effectiveness or safety. There are also significant concerns regarding hoodia’s thirst suppression and its potential for severe dehydration. We must be cautious for now and await a good, powered randomized-control trial. The safest and healthiest bet for weight loss seems to remain good old fashioned diet and exercise.

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