Garcinia Cambogia
Medically Reviewed on May 11, 2016 by J. Stewart, BPharmWhat is Garcinia cambogia?
Garcinia cambogia is an extract obtained from the dried fruit of the Garcinia cambogia (GC) tree, a native plant species of South India and South Asia.1,2 The fruit looks like a small green pumpkin, and is used extensively in Asian-style cooking for its sour flavor.
What is the active ingredient and how does it work?
The skin, or rind of Garcinia cambogia fruit contains large amounts of hydroxycitric acid (HCA). HCA is a derivative of citric acid, and is marketed as a weight loss supplement, either alone or in combination with other supplements.1,2
How HCA works to promote weight loss is not precisely known, but several theories exist. Some experts believe it works by inhibiting an enzyme called citrate lyase, interfering with the conversion of unused carbohydrates into fat. Although HCA does have this effect on carbohydrates in a laboratory petri dish, it is unproven whether it does this once inside the body.1,2
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Other experts suggest HCA affects other enzymes involved in carbohydrate metabolism, such as pancreatic alpha amylase and intestinal alpha glucosidase. A few postulate that it increases the release or availability of serotonin in the brain, promoting appetite suppression.1,2 Nobody knows for sure just how HCA works… or if it really does work.
Is there any evidence to support Garcinia cambogia as a weight loss supplement?
Several trials have investigated use of Garcinia cambogia for weight loss in humans. Some of these trials are of better quality than others, and reviews that group trials together to look for an overall effect give us a better “bigger picture” than just looking at the results of a single trial.
An analysis in 2011 by Onakpoya et al1 found 12 trials that investigated the effect of Garcinia cambogia for weight loss that matched their strict quality criteria. Although they found evidence that Garcinia cambogia did promote weight loss in the short term, the effect was small and barely significant. The same conclusion was reached in another review by Fassina et al2 in 2015 of 17 trials, both in humans and animals. Interestingly, in one of the largest individual trials of 135 people, both the active group (the group taking GC) and the control group (the group taking a placebo – or an inactive supplement) lost a significant amount of weight over a 12-week treatment period.3 As many other previous trials have suggested, it is often the support and encouragement people receive to lose weight that makes more of a difference than any diet or supplement.
In summary, evidence so far does not suggest Garcinia cambogia is effective as a weight loss supplement; although larger scale trails conducted over a longer period of time may shed more light on the subject.
For now, increasing physical activity levels, avoiding alcohol, and eating a healthier diet with more vegetables, whole grains, and less red meat is more likely to make you shed weight long-term than Garcinia cambogia supplements.
Is there any harm in taking Garcinia cambogia supplements?
It is important to remember that ANY product labeled as “natural” or “herbal” is not unquestionably safe. Herbal remedies classified as dietary supplements in the United States are regulated as food products. This means they have not been subjected to the same requirements for safety or efficacy as medicines.
Garcinia cambogia has been implicated in causing liver damage, both when used in combination with other ingredients (for example, in the original formulation of the product Hydroxycut) and when used by itself. Two severe cases are documented. The first was a 52-year-old female who developed severe liver failure requiring a liver transplant after taking 1000 mg of Garcinia cambogia for 15 days, and the other was a 42-year-old female who developed abnormally high liver function tests and coagulopathy (an impaired ability of the blood to clot) after one week of taking GC.4 The second lady recovered without incident several days after Garcinia cambogia was discontinued. Interestingly, the manufacturer of Hydroxycut temporarily withdrew the product, but it has since returned a reformulated version that lacks Garcinia cambogia to the market.5
Other reported adverse effects are generally mild when Garcinia cambogia is taken at the recommended dosage and include stomach upset, dry mouth, headaches, dizziness, and diarrhea.2,6 Herbal remedies should not be taken by women who are pregnant or breastfeeding and anybody with heart disease or other medical conditions should consult their doctor before use. Some studies have suggested that Garcinia cambogia can lower blood sugar or interfere with diabetes control, so it is particularly important if you have diabetes that you talk with your doctor.
On the positive side, unlike stimulants such as phentermine, Garcinia cambogia does not act on the central nervous system, so does not cause sleeplessness, anxiety, affect the heart or blood pressure, and its efficiency does not decrease with time.5,6,7
Does Garcinia cambogia have any effect on blood sugars?
There have been several contradictory claims about the effects Garcinia cambogia has on blood glucose control with some celebrity endorsements even suggesting it may be beneficial for people with diabetes. While studies in rats have shown a reduction in the amount of glucose absorbed and less of a spike in blood glucose levels following a meal, rats are not humans so studies were needed to determine if this also applied to humans.
