Hydroxycitric Acid
Also indexed as: Garcinia cambogia, HCA
What is it?
(-)-Hydroxycitric acid (HCA) is a compound found in Garcinia cambogia, a type of fruit. HCA has a chemical structure similar to that of citric acid (the primary acid in citrus fruits).
Preliminary research in the laboratory and in animal research, suggests that HCA may be a useful weight loss aid.1 2 HCA has been demonstrated in the laboratory (but not yet in trials with people) to reduce the conversion of carbohydrates into stored fat by inhibiting certain enzyme processes.3 4 Animal research indicates that HCA suppresses appetite and induces weight loss.5 6 7 8 One case report found that eating 1 gram of the fruit containing HCA before each meal resulted in the loss of 1 pound per day.9
A double-blind trial that provided either 1,500 mg of HCA or a placebo per day to 135 overweight men and women, who also were on a calorie-restricted diet, found after 12 weeks that the HCA supplementation did not produce a significant change in weight loss.10 Uncontrolled and/or preliminary evidence from several other human trials suggests the possibility that weight loss might occur;11 however, none of these studies is as methodologically strong as the negative trial previously mentioned. These less-rigorous studies used a similar calorie-restricted diet and a similar amount of HCA as the negative trial. However, the double-blind study used a high-fiber diet not used in the prior studies. It has been suggested that such a diet might limit absorption of HCA.12 Future studies that measure blood levels of HCA (to check whether or not the supplement was absorbed) are necessary to resolve this issue. At the present time, the effectiveness of HCA for weight loss remains unclear and unproven.
Where is it found?
HCA is found in only a few plants, with one rich source being the rind of a little pumpkin-shaped fruit called Garcinia cambogia, which is native to Southeast Asia. This fruit (also called Malabar tamarind) is used as a condiment in dishes such as curry.
HCA has been used in connection with the following conditions (refer to it for complete information):
Who is likely to be deficient?
Since it is not an essential nutrient, HCA is not associated with a deficiency state.
How much is usually taken?
Optimal amounts of HCA remain unknown. Although dieters sometimes take 500 mg of HCA three times per day (before each meal), this amount is far below the levels used in animal research (figured on a per-pound body weight basis). The effect of HCA is enhanced when used in conjunction with a low-fat diet, because HCA does nothing to reduce the caloric effects of dietary fat. Since HCA’s mechanism of action seems to be at least partially a blockade of conversion of simple sugars into fats,13 it is likely to work best in conjunction with a high simple sugar diet. HCA may therefore be less useful if it only offsets the negative effects of an otherwise unhealthy diet. High-fiber diets may impair absorption of HCA as noted above. HCA supplements are available in many forms, including tablets, capsules, powders, snack bars, and chewing gum.
Are there any side effects or interactions?
HCA has not been linked to any adverse effects.
At the time of writing, there were no well-known drug interactions with Hydroxycitric Acid.
References
1. Lowenstein JM. Effect of (-)-hydroxycitrate on fatty acid synthesis by rat liver in vivo. J Biol Chem 1971;246:629–32.
2. Triscari J, Sullivan AC. Comparative effects of (-)-hydroxycitrate and (-)-allo-hydroxycitrate on acetyl CoA carboxylase and fatty acid and cholesterol synthesis in vivo. Lipids 1977;12:357–63.
3. Cheema-Dhadli S, Harlperin ML, Leznoff CC. Inhibition of enzymes which interact with citrate by (-)hydroxycitrate and 1,2,3,-tricarboxybenzene. Eur J Biochem 1973;38:98–102.
4. Sullivan AC, Hamilton JG, Miller ON, et al. Inhibition of lipogenesis in rat liver by (-)-hydroxycitrate. Arch Biochem Biophys 1972;150:183–90.
5. Greenwood MRC, Cleary MP, Gruen R, et al. Effect of (-)-hydroxycitrate on development of obesity in the Zucker obese rat. Am J Physiol 1981;240:E72–8.
6. Sullivan AC, Triscari J. Metabolic regulation as a control for lipid disorders. Am J Clin Nutr 1977;30:767–76.
7. Sullivan AC, Triscari J, Hamilton JG, et al. Effect of (-)-hydroxycitrate upon the accumulation of lipid in the rat. I. Lipogenesis. Lipids 1974;9:121–8.
8. Sullivan AC, Triscari J, Hamilton JG, et al. Effect of (-)-hydroxycitrate upon the accumulation of lipid in the rat. II. Appetite. Lipids 1974;9:129–34.
9. Sergio W. A natural food, Malabar Tamarind, may be effective in the treatment of obesity. Med Hypotheses 1988;27:39–40.
10. Heymsfield SB, Allison DB, Vasselli JR, et al. Garcinia cambogia (hydroxycitric acid) as a potential antiobesity agent. JAMA 1998;280:1596–600.
11. Seroy S. Response to JAMA HCA report. Townsend Letter for Doctors and Patients Feb/Mar 1999:120–1 [letter/review].
12. Badmaev V, Majeed M, Conte AA. Garcinia cambogia for weight loss. JAMA 1999;282:233–4 [letter].
13. Lowenstein JM. Experiments with (-)hydroxycitrate. In: Burtley W, Kornberg HL, Quayle JR, eds. Essays in Cell Metabolism. New York: Wiley Interscience, 1970, 153–66.