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Source: Heymsfield SB, et al. Garcinia cambogia (hydroxycitric acid) as a potential antiobesity agent: A randomized controlled trial. JAMA 1998;280: 1596-1600.
Design and setting: Twelve-week randomized, double-blind, placebo-control-led trial in an outpatient weight control research unit in New York.
Subjects: 135 overweight men and women ages 18-65; mean BMI 32 kg/m2.
Treatment: Hydroxycitric acid (purported active ingredient in Garcinia cambogia) vs. placebo. Both groups were prescribed a high-fiber, low-energy diet (5040 kJ/d with 20% fat, 50% carbohydrate, and 30% protein).
Dose/Route/Duration: Two 500 mg caplets po tid taken 30 minutes before meals for 12 weeks. Total daily dose was 3000 mg herb containing 1500 mg hydroxycitric acid.
Outcome Measures: Body weight change and fat mass change.
Results: Patients in both groups lost weight, but there were no significant differences between the two groups. Reported adverse events were minor and not significantly different between the two groups.
Funding: NIH grants RR00645 and P30DK26687 and contract with Thompson Medical Company, manufacturer of products that include Garcinia.
Comments: Hydroxycitrate inhibits fatty acid synthesis, so there is a theoretical basis for possible efficacy, but this study demonstrates that Garcinia adds no benefit to a conventional weight loss plan. The authors note that their trial is longer than seven previous trials (all of which were four to eight weeks long, and five of which claimed a positive result for Garcinia). Additional comments on previous trials included the fact that five trials were not published in peer-reviewed journals and that five trials administered Garcinia with other potentially active ingredients, including chromium, caffeine, and L-carnitine.
This trial may be better than previously published trials, but limitations still exist, including lack of monitoring of diet compliance. Of most concern is the fact that only 62% of the subjects completed the trial. Although the dropouts appeared evenly divided between the two groups, inadequate information is provided about drop-outs—for 36 patients (27%) it is noted only that they were "lost to follow-up." In a long-term trial this may be more acceptable but that’s a lot of patients to disappear in a three-month trial.
All trials performed to date appear to have included a low-calorie diet; this is perhaps not an ideal circumstance in which to test a product that decreases lipid synthesis. It would be interesting to study if Garcinia has any effect when given to people who have not changed their diets.