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Does Hoodia Gordinii Really Work?

There's been a lot of talk about hoodia gordonii, a succulent indigenous to South Africa and Namibia that the natives have used to treat indigestion and to suppress appetite. Now Hoodia extract supplements are widely sold as an appetite suppressant, although its safety hasn't been well investigated and its effects haven't been sufficiently well established through high-quality research in humans.

There has been some research indicating that giving rats the active ingredient in hoodia has led to loss in body weight and reduced food intake. An unpublished study from 2003 looked at twice-daily administration of a similar concentration of the active ingredient in hoodia to human subjects, who then ate about 30% less than those taking a placebo.

You might be convinced already that you should go out and buy some hoodia. Look again at the second sentence in the first paragraph, where it says, "its safety hasn't been well investigated and its effects haven't been sufficiently well established." This is the issue with so many supplements: we don't know for sure if they're safe or even if there's a safe dosage or an unsafe dosage. Another issue is that of manufacture: for example, all of the Web sites I looked at that sell hoodia pills claim that theirs is the best, purest form of the extract and that all others are inferior and do not work. (Guess that's a good way to get people to buy more - if the pills you buy don't seem to work, you must have bought the wrong ones!) There's no way to know for sure whether you're getting the appropriate dosage, never mind that the pills you purchase may not contain the active ingredient at all, as the manufacturers are not required to prove that their products actually contain what they claim they contain.

Fortunately a study recently published in The American Journal of Clinical Nutrition (2011;94:1171-81) made use of a very pure form of the extract in a study involving 49 overweight and otherwise healthy women between the ages of 18 and 50. Twice daily, before breakfast and before dinner, the women were given a yogurt drink which they were told was the study product. They were not told, however, that half the women were receiving 1110 milligrams of extract of hoodia in the yogurt drink, while half were not. (The hoodia extract concentration in this study was the same concentration of the active ingredient as that unpublished study mentioned above.)

For 14 days the women lived at the test site and received all of their meals there. For the first 4 days of the study all of the women received the placebo (unmedicated) drink, then on the fifth day those assigned to the medication started receiving hoodia in their yogurt drink. While living at the test site all of the women received standardized meals in portions larger than their usual size and were told additional portions were available if they so desired. Snacks were also made available. The amount of food each woman ate was measured and recorded. After the live-in period the women returned home to their usual diets and continued taking the yogurt drinks as directed.

Before the start of the study and at regular intervals throughout the study, the women's body weight, fat mass and caloric intake were monitored, while their blood as also tested. Any side effects the women experienced were also recorded and investigated further where necessary to exclude the possibility that the effects were not caused by something other than the treatment medication. The most common side effects experienced were nausea and vomiting (two women could not complete the study because of it), dizziness or giddiness, "disturbance of skin sensation" and headache. All of the women experiencing side effects turned out to be among those women in the treatment group.

The researchers found that not only was there no significant difference between the amount the treatment group ate compared to the placebo group ate, their body fat mass did not significantly change either. However, those who were taking the hoodia saw increases in their blood pressure, heart rate and bilirubin levels (liver enzymes), which returned to normal shortly after they stopped taking the hoodia.

What this means for you

This research was funded by Unilever, one of the largest food conglomerates in the world. Given the high demand for obesity drugs, you would think they would have a strong interest in finding that hoodia, or some other substance, would be a "wonder drug," as hoodia is touted to be. It seems clear, from this well-designed study, that it's not. Save your money and invest in great-tasting food for your health.

First posted: October 26, 2011