Friday, April 23, 2010

Hoodwinked by Hoodia? by Jerry Brainum

Fat-loss supplements are a big business. In the never ending quest to lose body fat effortlessly, a variety of nostrums are constantly being offered. Such formulas appeal mainly to those who abhor the idea of following a strict fat-loss diet and are too lazy to burn off calories at the gym or in other physical activity. Others, however, do exercise and attempt to diet, only to be met with frustration as the pounds fail to come off rapidly enough, or just don't seem to come off at all. One of the more popular and controversial putative fat-loss supplements in recent years has been an extract of a plant from South Africa known as Hoodia.
    Hoodia looks like a cactus, but isn't. It also smells somewhat like a decaying corpse. But that didn't deter the indigenous San Bushmen of the Kalahari desert from sucking on the root of the Hoodia plant. They did this because of their nomadic existence in the arid Kalahari, where they often went on long treks during which they hardly ate or drank anything. The folk wisdom held that they were able to accomplish this feat because of their use of Hoodia. Eventually, the South African government investigated the alleged potent appitite-supressing effects of  Hoodia in 1963. By the 1980s, the active ingredient of Hoodia was isolated, a substance dubbed P57, because it was the 57th compound tested in Hoodia. In 1995, a patent was issued to the Phytopharm company,who had spent $20 million isolating P57. The company soon sub-licensed the use of Hoodia to the pharmacuetical giant, Pfizer, who provided $21 million for this courtesy. But Pfizer relinquished the use patent in 2003. In that same year, the South African government responded to a grass roots effort to share any profit from Hoodia to the impoverished Sans Bushman. The excuse provided by the government for not doing this previously was that they thought none of the tribe still existed. In fact, thousands of them did.
    Hoodia is thought to work by way of its P57 content. In the brain, P57 is mistaken for glucose, the primary fuel for the brain. This somehow tricks the brain into increasing its ATP level. When ATP levels are high in the appitite center of the brain, appitite is turned off. This is what food usually does. So in essence, Hoodia makes the brain think you just ate a full meal. In an unpublished study commissioned by the company that controls the Hoodia use patent (owned by the South African government), 18 human subjects were divided into a group that either received Hoodia or a placebo. The Hoodia group ingested 1,000 fewer calories a day compared to those in the placebo group. But what really got worldwide attention was a segment of the television news show, 60 Minutes. During that show, reporter Leslie Stahl traveled to South Africa and ingested some Hoodia. She said that she lost her appetite completely and didn't eat anything for the entire day after ingesting the Hoodia. 
     In terms of published proof of the efficacy of Hoodia for promoting weight-loss, the evidence is scarce. In one study of rats P57 from Hoodia was provided to the rats, which resulted in a 50-60% reduction in food intake over a 24-hour period. The problem was that the P57 in the study was injected directly into the rat's brains.In the most recent study, mice were provided P57 either intravenously, or orally. The oral route showed a peak blood level of P57 in just over 30 minutes, and 47.5% of the dose was absorbed. In both the oral and intravenous routes, P57 was eliminated from the body in four hours. But the oral route, while showing absorption into the blood, was not detected in the rodent's brains. This is problematic because the brain is where P57 is supposed to work. The intravenous administration of P57 did show up in the brain, but in very small amounts.
      In addition to the questionable effect of oral Hoodia, most of what is being sold on the market, particularly over the Internet, does not contain any of the active ingredient of Hoodia, P57. Indeed, one estimate is that 80% or more of "Hoodia supplements" are fakes.Adding to the problem is that Hoodia was declared an endangered plant, and the use of actual Hoodia has been curtailed by the South African government. What's needed now is more human evidence of the efficacy of Hoodia, since the active ingredient, P57 appears able to enter the brain only when provided intravenously or injected directly into the brain.

Vamsi L, et al. Bioavailability, pharmacokinetics, and tissue distribution of the oxypregnane steroidal glycoside P57 from Hoodia gordonii in mouse model. Planta Medica 2010: in press.

©,2011 Jerry Brainum.Any reprinting in any type of media, including electronic and foreign is expressly prohibited.     

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