The garcinia gummi-gutta plant, sometimes also referred to by its previous scientific name of garcinia cambogia, is another in a long line of herbal extracts with purported weight loss effects.
It’s a tree native to Indonesia whose fruit has been used for a wide range of applications in southeast Asia.
As is often the case with unknown herbal supplements, garcinia cambogia extract rocketed to fame after being featured on the Dr. Oz Show.
There’s seemingly no end to the torrent of exotic plants, fruits, and vegetables that are claimed to hold the key to fast, safe, and effective weight loss. Though a cynic might dismiss the constant parade of new weight loss supplements from these plants as a waste of time, it is admittedly the case that many drugs that are now mainstays of medical treatment were once exotic or little-known herbal extracts (like forskolin).
The short answer for garcinia cambogia: there is some evidence that it might help, but studies can’t prove it.
Lab animal research on garcinia cambogia extract
Interest in garcinia cambogia first arose after research in rodents appeared to demonstrate a fat-burning effect. A 2003 study published by K. Hayamizu and other researchers at Kyushu University in Japan investigated the effect of a garcinia cambogia extract in mice who were fed an obesity-inducing diet (1).
Lab mice were fed a diet consisting of 10% pure sugar by weight, a standard procedure for inducing fat gain in lab animals (and one that many humans unwittingly replicate). Half the mice were given fed a 3.3% garcinia cambogia extract, while the other half were given no special supplementation. Over the course of the four-week study, the mice fed garcinia cambogia did gain any less weight than those which were not, but they did have beneficial effects on glucose metabolism and levels of a hormone called leptin, which signals fullness. Theoretically, if leptin levels are raised enough, you should feel full faster and eat less at meals.
Though leptin levels rose, the mice’s body weight did not change, which could be for any number of reasons—perhaps the study wasn’t long enough to effect a change, the change in leptin levels wasn’t of great enough of a magnitude to change appetite, or possibly the appetite lowering effects were countered by another effect of the garcinia cambogia extract.
Another more thorough study found a more direct anti-obesity effect. A 2013 study in the World Journal of Gastroenterology by researchers at Kyungpook National University in South Korea (2). Over the course of 16-week study, obesity-prone mice were fed a high-fat diet; half of the mice’s food had 1% garcinia cambogia extract by weight added to it. At the study’s conclusion, neither group of mice differed with respect to their body weight or food consumption, but the mice fed garcinia cambogia extract did have less visceral fat (“belly fat“) than the mice on the standard diet. Further, by analyzing the activity of enzymes inside fat cells, the researchers were able to determine that this was likely a direct result of an inhibition in the activity of a particular enzyme that is responsible for synthesizing fatty acids inside fat cells.
Notably, the researchers also discovered that the mice fed garcinia cambogia extract showed increased fibrosis in their liver and signs of increased oxidative stress throughout their body. This raises concerns about the safety of garcinia cambogia extract in humans; if it causes liver damage, taking it could be a very bad idea. The hepatoxicity of garcinia cambogia extract, or its potential to cause liver damage, was questioned by a later paper published by D.L. Clouatre and H.G. Preuss in the same scientific journal (3).
Clouatre and Preuss argued that garcinia cambogia extract has several studies that attest to its safety. Perhaps to no surprise, Clouatre and Preuss work for a supplement manufacturing company in Washington, which introduces some potential for bias.
Studies in humans on garcinia cambogia‘s weight loss properties
Regardless, human trials of garcinia cambogia extract as a weight loss have been conducted. An experiment described in the Journal of the American Medical Association studied 135 overweight volunteers split into two groups (4).
Per standard protocol, one group was given a garcinia cambogia extract to take every day (1500 mg of hydroxycitric acid, the main ingredient in garcinia cambogia), while the other group was given a placebo. After twelve weeks of treatment, which also incorporated a high fiber diet for all participants, the results showed that the garcinia cambogia extract had no effect on weight lost, percentage of body fat lost, or proportion of lost weight that was fat. Both groups did lose weight to the tune of about seven to nine pounds, on average. This, however, was assuredly the result of the high fiber diet and not the garcinia cambogia extract.
A few other small trials of garcinia cambogia extract have been conducted, but some of the data are unpublished. In a 2004 review article by Max H. Pittler and Edzard Ernst at the Universities of Exeter and Plymouth in the United Kingdom, the evidence for garcinia cambogia extract as a weight loss supplement was described as “not compelling” (5).
Garcinia cambogia extract: little evidence so far
The bottom line on garcinia cambogia extract is there is little evidence suggesting it helps weight loss.
None of the above studies found a direct fat loss effect due to garcinia cambogia.
Although it may have some minor effects when it comes to modulating the activity of enzymes inside fat cells and levels of leptin, the fullness hormone, neither of these changes have enough of an effect to actually induce any weight loss.
Further, the research showing chronic liver damage in mice fed garcinia cambogia extract is troubling—though these mice probably ate much more garcinia cambogia by body weight than most humans would, it is still cause for concern.
No comments:
Post a Comment