April 19, 2005
An Appetite Killer for a Killer Appetite? Not Yet
he way the San people of the Kalahari Desert describe it, Hoodia gordonii is nature's hunger buster. Break off a spiny, cucumber-shaped stalk from this succulent plant, feed on its milky center and you will have the energy to set off on a long hunt unencumbered by hunger pangs.
Or, if you live far from the arid regions in South Africa, Botswana and Namibia where hoodia grows, simply buy one of many new brands of hoodia supplements.
In the past few years, after reports that Pfizer, the pharmaceutical company, had begun looking into hoodia's potential as an appetite-control drug, the market for hoodia that has been dried, powdered and fashioned into capsules has been growing fast. "The demand is very high, and the supply is ridiculously low," said Hugh Lamond, who runs Herbal Teas of Africa, one of a handful of hoodia exporters. "It's like shark-feeding time."
One supplement, called Hoodoba, advertises online that it "kills your appetite, ups your mood and gives you waves upon waves of energy."
The makers of Pure Hoodia, another brand, boast that the product contains an active ingredient that "fools your brain into believing you are full, making it easier to lose that excess weight."
Yet no human studies gauging the effectiveness or safety of the hoodia plant or of supplements made from it have been published.
That is why many physicians who specialize in weight loss do not recommend hoodia.
"In good conscience, I can't recommend something when the benefits are unproven and the health risks are unknown," said Dr. Jonathan Waitman, a nutrition specialist at NewYork-Presbyterian/Weill Cornell hospital's weight control program.
Dr. Madelyn Fernstrom, director of the weight management center at the University of Pittsburgh, said it would not be surprising to find foods "that might stimulate or suppress hunger."
But even if eating the plant dampens the San people's hunger, she said, that does not mean that processed supplements necessarily work the same way. For one thing, people who take the supplements do not get as much exercise as the San people do and have easier access to food.
Even assuming hoodia can affect appetite, there are many other unknowns, including how much of the supplement a person needs to consume to achieve that effect, how often someone can safely take it and how long it will keep working.
One unpublished study by a British company found that nine men who took an unspecified amount of P57, said to be the active ingredient in hoodia, twice a day for 15 days ended up eating fewer calories and losing more body fat than did a like-size group of men who took placebos. But the study was small and short. And because it has not been published in a journal, scientists cannot examine the details of how it was conducted or what it found.
The study was done by Phytopharm, a British company that in 1997 acquired a license from South Africa's Council for Scientific and Industrial Research to develop P57. The council had previously isolated P57 from Hoodia gordonii and identified it as the ingredient responsible for appetite control.
Phytopharm teamed up with Pfizer to develop a drug containing P57. But by mid-2003, Pfizer lost interest. Kate Robins, a spokeswoman for Pfizer in New London, Conn., explained that early research suggested that P57 would be too difficult to synthesize and could not readily be made into a drug in pill form.
Now, Phytopharm has teamed up with Unilever, the consumer products company that makes cleaning products, deodorant and a wide variety of foods, to look for ways to use P57 in foods and beverages. That effort will require studies to gauge the ingredient's safety and effectiveness, and no products are expected for at least three years, said Trevor Gorin, a spokesman for Unilever in London.
The new demand for hoodia, a wild plant, has led to a sudden surge in collecting it. As a result, it has been placed on the endangered species list. Mr. Lamond of Herbal Teas and other exporters have established hoodia farms in South Africa to provide a legal source of supply.
Unilever has done preliminary tests on 10 different supplement brands available in the United States, Mr. Gorin said, and has found that two contain no significant quantities of P57, four contain small amounts of it, and four contain significant amounts.
Hoodia supplements come in a variety of formulations, some containing other ingredients like green tea extract and cocoa extract. Bottles containing 60 capsules of varying strengths cost anywhere from $20 to $60.
How does hoodia work? Laboratory research, supported by Pfizer, in which P57 was injected into the brains of rats, indicated that it might act on the hypothalamus, a center of appetite control. Dr. David MacLean, an endocrinologist at Brown Medical School, who conducted the study, said the substance appeared to alter energy metabolism in that part of the brain.
But Dr. MacLean said that P57 was easily broken down by the liver, so it might be hard to take in enough of it to ensure that it had an effect. He cautioned that currently available supplements might be inadequate.
"I question whether there is really enough of the active ingredient in there to do much," Dr. MacLean said.
The possibility that hoodia is processed in the liver is cause for concern, given that many obese people often have liver abnormalities that could compound any side effects, said Dr. Michael Steelman, a weight loss specialist in Oklahoma City. "Anyone who uses this should use it under a doctor's supervision," Dr. Steelman said.
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