I first wrote about Hoodia in my “SkepDoc” column in Skeptic magazine (Vol. 13, No. 1, 2007). The following is adapted from that column with an update from new research revealing that it doesn’t work and that it causes worrisome side effects.
I first heard of Hoodia in 2006, when a radio ad informed me that it was the new miracle weight loss pill. Shortly after that, I started seeing ads for Hoodia everywhere. Anna Nicole Smith took it. It was featured on Oprah. Lesley Stahl went to Africa to taste the plant on 60 Minutes. There are nearly 40 competing brands of pills, a patch version, and even a Hoodia lollipop. It seems to have taken the world by storm; but it’s not new.
Hoodia gordonii is a cactus that grows in the deserts of southern Africa, and the San people have traditionally used it as an appetite suppressant, thirst quencher and to treat severe abdominal cramps, hemorrhoids, tuberculosis, indigestion, hypertension and diabetes. The claim is that it banishes hunger and thirst. What is the evidence? At this point it’s strictly anecdotal. Skinny Bushmen report it relieves hunger pangs in starvation conditions on long hunts; we don’t know what happens if it’s used by lazy fat people with access to food. Before the new study, there hadn’t been a single published study in humans.
The African Council for Scientific and Industrial Research isolated the active ingredient, P57, in 1977. They granted a license to Phytopharm, who collaborated on research with the pharmaceutical company Pfizer.
Pfizer eventually gave up on Hoodia due to the difficulty of synthesizing P57, and released their rights to it. Jasjit Bindra, Pfizer research scientist, said there were other components in Hoodia that damaged the liver and could not be easily removed from the supplement. He advised:
Until safer formulations are developed, dieters should be wary of using it.
In 2008, Unilever dropped its plans to market a Hoodia product after spending over 4 million pounds on research. Phytopharm continued to investigate it. Meanwhile, Hoodia is readily available as a diet supplement.
As well as being scientifically unsupported, Hoodia is politically incorrect. For one thing, it has been “stolen” from its original owners, the San people. Legally, it can only be exported under license, to guarantee patent rights and return a portion of the profits to the San people. Some of the trade in Hoodia is clearly illegal: at least one poacher has already been arrested. For another thing, Hoodia is a protected species. It grows wild, only in a small area, and takes several years to mature. It has not yet been successfully cultivated. Uncontrolled harvesting could wipe it out. There’s not enough available to supply all the products said to contain it. Products that have been tested have contained between 0.1 and 0.01 percent of the active ingredient claimed. One testing company estimated that half of the Hoodia products they test contain no Hoodia at all.
The FTC had received over a hundred complaints as of 2007. ConsumerLab concluded that Hoodia had not been proven safe or effective, and the quality of products is uncertain. Consumer Reports on Health recommends against taking products containing Hoodia. Even herb-friendly Andrew Weil recommends caution on his website.
I concluded my 2007 article with:
You have no way of knowing whether you’re getting the real thing; and if you are, you may be ripping off the San people or endangering a species. You have no way of knowing if the real thing works or if it’s safe. Other than that, it’s probably a great product!
A 2011 review found that:
Publications based on scientific studies of key aspects such as in vivo biopharmaceutics, the biological activity of all chemical constituents, clinical efficacy, and especially safety are insufficient or completely absent causing great concern as H. gordonii is one of the most widely consumed anti-obesity products of natural origin.
Finally, A Human Study
Now a new study published in October 2011 in the American Journal of Clinical Nutrition by Blom et al. has revealed that it doesn’t work and that it causes side effects. It was a randomized placebo-controlled double blind clinical study of 49 healthy overweight women. They were carefully monitored as inpatients, given either an H. gordonii extract or a placebo for 15 days after a 4 day run-in period, and were allowed to eat as much as they wanted. The researchers took a lot of precautions such as not letting subjects watch each other eat and standardizing the food so they could accurately measure calorie intake. I was impressed that the study was well-designed, carefully executed, and fully described even down to the brand and model of the machine used to do EKGs. The authors were employees of Unilever and Phytopharm, which holds the worldwide license for the application of H. gordonii extract in weight management products. The study results are a let-down for Big Pharma and are just the opposite of what might have been expected from researcher bias.
They found no significant difference in calorie intake or weight loss. They found significant and sustained increases in blood pressure, pulse, heart rate, bilirubin, and alkaline phosphatase. And they found a significantly higher incidence of side effects including nausea, vomiting, and disturbances of skin sensation. No serious reactions occurred, and a number of other tests (other liver function tests, hematocrit, cholesterol, EKGs, etc.) showed no significant change. Although subjects were not told to reduce their food intake, both groups ate less and lost an average of 1.2 kg, showing that just being enrolled in a study had an effect on behavior.
At this point I think it is reasonable to give up on H. gordonii. It doesn’t produce weight loss, and it causes a number of adverse effects. There is no miracle product that will magically decrease your hunger and melt the pounds off. Don’t be Hoodia-winked.