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Hoodia for weight loss - where's the evidence?

Friday, June 26, 2009 Posted by Travis Saunders
Photo by Amrum.
If you have passed through the weight-loss aisle at any pharmacy over the past few months, you will probably have seen several products claiming to contain Hoodia gordonii, more commonly known as Hoodia. This is particularly so given the empty shelf space created by the recent recall of all Hydroxycut weight-loss supplements (discussed here). Hoodia is a type of succulent (a type of plant that looks like a cactus, but is in fact completely different) which is said to have been used by the San Bushmen of the Kalahari desert to ward off hunger and thirst. Hoodia first came to prominence when the South African government suggested that extracts from the Hoodia plant caused a decrease in appetite and body weight in animals. Since then, a Hoodia diet pill has been under development by Phytopharm, a pharmaceutical company based in the United Kingdom. However, while the "official" Hoodia pill from Phytopharm remains to this day under development, countless other Hoodia products have hit the shelves as supplements claiming to reduce appetite and body weight.

Despite the ample hoodia based products currently availabe for sale, you may be surprised to find out that the clinical evidence supporting the use of Hoodia is practically non-existent.

On their website, Phytopharm reports on an in-house (and unpublished) study where Hoodia was found to significantly reduce both caloric intake and body weight over a period of two weeks in a group of overweight individuals. Although I could not find any further details about the magnitude of weight loss on the Phytopharm website, a review article in Obesity Management by Drs George Bray and Donna Ryan reports that the weight loss observed in the Hoodia group was a relatively modest 0.98 kg over the two week period. Unfortunately that is the only additional detail provided by Drs Bray and Ryan, and it remains unclear what dosage of Hoodia was provided to the subjects, or if the weight loss in the Hoodia group was significantly different from that in the control group.


Believe it or not, that's about the only clinical evidence supporting the use of Hoodia whatsoever, and the details haven't even been published in a peer reviewed journal!

There is one other study reporting that Hoodia injected directly into animal brains reduces food intake by 40-60% over a 24 hour period, but that's obviously not very relevant to the present discussion - as far as I know, none of the Hoodia products commercially available involve injection into the brain.

Given the lack of research, it's not surprising that on their website, the Mayo Clinic says that "There is no conclusive evidence that hoodia is an effective appetite suppressant or that it contributes to significant, long-term weight loss."

In addition to the complete lack of published clinical research on Hoodia, there are also serious questions about the quality of many products claiming to contain Hoodia. Hoodia is a rare plant, and Phytopharm has an exclusive deal with the South African government for most of it. It's not surprising then, that it's been reported that about 60% of products claiming to contain Hoodia may contain no Hoodia at all.

So let's recap.

1) There is no conclusive evidence suggesting that Hoodia produces long-term weight loss in humans. Phytopharm might eventually come out with a peer-reviewed study on the subject, but their former partner Pfizer got out of the Hoodia game in 2003, and it's been 8 years since their original (unpublished) clinical trial was completed.

2) Even if Hoodia is effective in promoting weight loss, there's still a 60% chance that the products that are currently available won't contain any Hoodia anyway.

The folklore about Hoodia being used by the San Bushmen is intriguing, but does not provide direct evidence of its efficacy in producting any appetite-suppressing or weight loss effects. At the moment, there's no conclusive evidence suggesting that any Hoodia product will help you lose weight, or keep it off. Thus, as with most commonly touted 'solutions' for excess weight, until peer-reviewed evidence supports Hoodia for weight-loss, you're better off saving your money.

For further reading on Hoodia, check out the discussion on WebMD here.

Travis

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Bray, G., & Ryan, D. (2006). Supplements Used in Weight Management Obesity Management, 2 (5), 186-189 DOI: 10.1089/obe.2006.2.186

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1 Response to "Hoodia for weight loss - where's the evidence?"

  1. Jen Said,

    This is a good point. Most people get into this supplements not considering whether there are supporting evidence of what the product is capable of doing and the safety of its use.

    And they advantage of the vulnerability of most people that want to lose weight.

    Posted on June 28, 2009 at 2:49 PM

     

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We are PhD students in the School of Kinesiology and Health Studies at Queen's University in Kingston, Ontario. Our research focuses on the relationships between obesity, physical activity, and health risk. This blog is our attempt to consider the many "cures" for obesity that we read about on a daily basis. Enjoy.

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