Hoodia: Lots of Hoopla, Little Science (cont.)

Because it is sold as a dietary supplement, hoodia escapes the level of scrutiny the FDA gives prescription drugs and medications sold over the counter.

The Science

Hoodia does have some evidence to back it up, says Mark Blumenthal, founder and executive director of the American Botanical Council, a nonprofit research organization in Austin, Texas. He cites one laboratory study but says the evidence is not conclusive.

"We can only say the evidence available to us right now, which is considered inadequate, suggests that there is some type of appetite-suppressing mechanism in some of the naturally occurring chemicals in hoodia," Blumenthal says. He adds that his organization has not received any consumer reports of safety problems with hoodia use.

The laboratory evidence Blumenthal refers to was produced by David MacLean, MD, an adjunct associate professor at Brown University in Providence, R.I., and a former researcher at the pharmaceutical giant, Pfizer. In a report published in the Sept. 10, 2004, issue of Brain Research, MacLean reported that a molecule in hoodia, called P57, likely has an effect on the brain's hypothalamus, which helps regulate appetite. His study was done in animals.

In an email response to WebMD, MacLean says a cousin of hoodia's P57 molecule may eventually prove to be the better answer. "A chemical within that class of molecules has real potential to reduce appetite," he says. "I'm less confident regarding the hoodia molecule itself for reasons relating to its metabolism [absorption and breakdown] in humans."

About the time MacLean's article was published, Richard M. Goldfarb, MD, a doctor in Morrisville, Pa., conducted a study of Hoodia gordonii on people and found it effective. His study was small, just seven people, says Goldfarb, medical director of Bucks County Clinical Research, an organization that conducts studies for pharmaceutical and other companies.

Goldfarb's Study

Goldfarb studied DEX-L10, the 500-milligram hoodia capsules sold by Delmar Labs. Goldfarb did the study for the manufacturer but says he was not paid for the research. "I did it as a service to them," he says.

In Goldfarb's study, the seven overweight participants were told to take two Hoodia gordonii (DEX L-10) capsules a day, eat a balanced breakfast and take a multivitamin, and keep other eating and exercise habits unchanged. The participants' starting weights ranged from 193 to 345 pounds. They lost, on average, 3.3% of their body weight, Goldfarb says. The median loss over the 28-day study was 10 pounds (half lost more, half less).

Most of the participants reported their caloric intake dropped to less than half within a few days after starting hoodia, and they didn't report side effects such as jitteriness or insomnia, Goldfarb says.

The study was not published in a scientific journal nor presented at a medical meeting, Goldfarb says, because it was conducted as an "efficacy" study, trying only to find out if the product actually works.