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09.01.2011

One and a half grams HCA has no effect at all

Garcinia cambogia does nothing at all, according to the biggest independent study so far published on this popular slimming supplement. At least, not a dose of 1500 mg per day.

Citric acid Hydroxy citric acid

Garcinia cambogia is a plant with a pumpkin-shaped fruit from India, which contains hydroxycitric acid or HCA [structure shown at the bottom here]. Health food shops also sell garcinia products under the name of Malabar Tamarind. Roche did many years of research on HCA. Enzymes convert excess glucose in the body into citric acid, and ultimately convert citric acid into fat. Hydroxycitric acid causes a key enzyme in the complex reaction – citrate lyase – to get stuck. This forces the body when it's resting to burn more carbohydrates and when moving to burn more fats.

A promising theory. But independent human studies have shot it down in flames. The largest was done by obesity researchers at Columbia University and was published in the prestigious JAMA. In the study 135 overweight men and women were given 1500 mg hydroxycitric acid daily for 12 weeks – or a placebo. The subjects took 500 mg HCA three times a day, 30 minutes before a meal.

The subjects followed a diet that provided them with 1200 kcal a day. At the end of the 12 weeks the placebo group had lost 4.1 kilograms. The garcinia group had lost 3.2 kilograms.

In the same period another study was published in which 89 overweight women had been given 1200 mg HCA daily. When the researchers examined whether the extract decreased the test subjects' appetite, they observed no effect. [Physiol Behav. 2000 Oct 1-15; 71(1-2): 87-94.]

Even more negative were the results of a Dutch human study that were published in 2000 in the American Journal of Clinical Nutrition. [Am J Clin Nutr. 2000 Dec;72(6):1445-50.] In this study trained endurance athletes were given a placebo or 3-5 g HCA during a cycling exertion test that lasted two hours. The figure below shows that HCA had no effect on the amount of carbohydrates or fats that the test subjects burned.

Usually we round off our articles with a conclusion, a take home message. In this case it's not necessary.

Source:
JAMA. 1998 Nov 11; 280(18): 1596-600.