Hydroxycitric acid (HCA) is a major acid component of the tropical plants Garcinia cambogia - a plant native to Southeastern Asia - and Hibiscus subdariffa. The availability of hydroxycitric acid is limited by the restricted habitat of the plants as well as the difficulty of making hydroxycitric acid in the laboratory.

Natrol Pure Citrimax, 250 mg., Hydroxycitric Acid HCA

Natrol's Pure CitriMax is derived from the dried rind of Garcinia Cambogia, a native fruit of India. CitriMax contains high concentrations of (-) hydroxycitric acid (HCA), verified by HPLC to guarantee potency and quality.

CitriMax Supplement Facts:
(-)Hydroxycitric Acid (HCA) - 250 mg
     (Standardized Extract from Garcinia cambogia [fruit])

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Diet Rx natural appetite suppressant with hydroxycitric acid
If you would like to eat less, consider a product called Diet Rx with green tea extract, hoodia extract, hydroxycitric acid and effective diet herbs and extracts. This natural appetite suppressant works without stimulants. Diet Rx has no added caffeine, ephedra, ephedrine alkaloids, synephrine, hormones, guarana, ginseng, or stimulating amino acids. 

Benefits of Diet Rx
All natural appetite suppressant, decreases appetite so you eat less
Helps you maintain healthy blood sugar levels. When you eat less, there is a lesser likelihood that blood sugar will rise as high.
Helps you maintain healthy cholesterol and lipid levels
Provides a variety of antioxidant from two dozen herbs and nutrients
Provides healthy fiber
Improves energy
Balances mood
Improves mental concentration and focus
Improves will power and choice of food selection

You can buy Diet Rx here, find out the ingredients, and see a list of hundreds of high quality natural supplement products

Subscribe to a FREE Supplement Research Update newsletter. Once or twice a month you will receive an email of several studies on various supplements and natural medicine topics, including HCA hydroxycitric acid research, and their practical interpretation by Ray Sahelian, M.D.  

Hydroxycitric Acid in Garcinia Cambogia
Hydroxycitric acid is found in a high concentration - ranging from 10 to 30% - in the dried fruit rind of Garcinia cambogia. The dried rind has been used for centuries throughout Southeast Asia as a food preservative, flavoring agent and carminative. Extensive experimental studies show that Hydroxycitric acid inhibits fat synthesis and reduces food intake.

How Hydroxycitric acid works
The primary mechanism of action of hydroxycitric acid appears to be related to its ability to act as a competitive inhibitor of the enzyme ATP-citrate lyase, which catalyzes the conversion of citrate and coenzyme A to oxaloacetate and acetyl coenzyme A (acetyl-CoA), primary building blocks of fatty acid and cholesterol synthesis.
     Hydroxycitric acid from Hibiscus subdariffa inhibits alpha-amylase and alpha-glucosidase, leading to reduction of carbohydrate metabolism.

Hydroxycitric Acid HCA and Weight Loss
Hydroxycitric acid has been reported to promote body fat loss in humans without stimulating the central nervous system. The level of effectiveness of G. cambogia extract is typically attributed solely to hydroxycitric acid. However, other components may contribute to its therapeutic effectiveness. Results thus far with hydroxycitric acid and weight loss appear to be promising.

Hydroxycitric Acid Research Update
Efficacy of a novel calcium/potassium salt of (-)- hydroxycitric acid in weight control.
International J Clin Pharmacol Res. 2005;25(3):133-44. Preuss HG, Garis RI, Bramble JD, Bagchi D, Bagchi M, Rao CV, Satyanarayana S. Department of Physiology and Biophysics, Georgetown University Medical Center, Basic Science Building, N.W., Washington, DC
The weight-loss efficacy of a novel, water-soluble, calcium-potassium salt of (-)- hydroxycitric acid HCA was re-examined in 90 obese subjects (BMI: 30-50.8 kg/m2). We combined data from two previously reported randomized, double-blind, placebo-controlled clinical studies in order to achieve a better statistical evaluation based on a larger population. This re-examination of data also allowed us to reflect more intensely on various aspects of weight loss studies. Subjects were randomly divided into three groups: group A received a daily dose of hydroxycitric acid 4, 667 mg (providing 2,800 mg hydroxycitric acid per day); group B was given a daily dose of a combination of hydroxycitric acid 4,667 mg, niacin-bound chromium (NBC) 4 mg (providing 400 microg elemental chromium), and Gymnema sylvestre extract (GSE) 400 mg (providing 100 mg gymnemic acid); and group C received a placebo in three equally divided doses 30-60 min before each meal. All subjects were provided a 2,000 kcal diet/day and participated in a supervised walking program for 30 min/day, 5 days/week. Eighty-two subjects completed the study. At the end of 8 weeks, in group A, both body weight and BMI decreased by 5%, low-density lipoprotein and triglycerides levels were reduced by 12% and 6%, respectively, while high-density lipoprotein levels increased by 8.9%, serum leptin levels decreased by 38%, serotonin levels increased by 44% and urinary excretion of fat metabolites increased by 32-109%. Group B demonstrated similar beneficial changes, but generally to a greater extent. No significant adverse effects were observed. The combined results confirm that hydroxycitric acid and, to a greater degree, the combination of hydroxycitric acid plus NBC and GSE reduce body weight and BMI, suppress appetite, improve blood lipid profiles, increase serum leptin and serotonin levels and increase fat oxidation more than placebo. We conclude that dosage levels, timing of administration, subject compliance and bioavailability of hydroxycitric acid significantly affect results and that when taken as directed, hydroxycitric acid is a highly effective adjunct to healthy weight control.

Comparison of the effects of three different (-)-hydroxycitric acid preparations on food intake in rats.
Nutr Metabolism (Lond). 2005 Sep 13;2:23.
Studies on the effects of (-)- hydroxycitric acid (HCA) in humans are controversial. As differences in the hydroxycitric acid preparations may contribute to this apparent discrepancy, the aim of the current study is to compare different hydroxycitric acid -containing preparations in adult Wistar rats. The effects of 3 different hydroxycitric acid -containing preparations (Regulator, Citrin K, Super CitriMax HCA-600-SXS, all used at an effective hydroxycitric acid dose of 150 and 300 mg/kg, administered intragastrically) on food intake and body weight were studied in adult male Wistar rats. The efficacy was tested under 2 different experimental conditions: 1) after a single dose administration and 2) during repeated administration for 4 subsequent days. Regulator and Citrin K significantly reduced food intake in both experimental setups, while Super CitriMax HCA-600-SXS was less effective. When administered for 4 subsequent days Regulator and Citrin K diminished body weight gain. CONCLUSION: Regulator and Citrin K were shown to be potent inhibitors of food intake in rats, whereas Super CitriMax HCA-600-SXS showed only small and more inconsistent effects. The striking differences in efficacy between these 3 preparations indicate that low doses of a relatively low-effective hydroxycitric acid preparation may have contributed to the lack of efficacy as found in several human studies.

Hydroxycitric acid delays intestinal glucose absorption in rats.
Am J Physiol Gastrointest Liver Physiol. 2005 Jun;288(6):G1144-9.
In this study, we investigated in rats if hydroxycitric acid (HCA) reduces the postprandial glucose response by affecting gastric emptying or intestinal glucose absorption. We compared the effect of regulator hydroxycitric acid (310 mg/kg) and vehicle (control) on the glucose response after an intragastric or intraduodenal glucose load to investigate the role of altered gastric emptying. Hydroxycitric acid treatment decreased concentrations of [U-(14)C]glucose in small intestinal tissue at 15 min after [U-(14)C]glucose administration, in accordance with the concept that hydroxycitric acid delays the enteral absorption of glucose. These data support a possible role for hydroxycitric acidas food supplement in lowering postprandial glucose profiles.

Effect of hydroxycitrate on respiratory quotient, energy expenditure, and glucose tolerance in male rats after a period of restrictive feeding.
Nutrition. 2004 Oct;20(10):911-5.
Recently we demonstrated that hydroxycitrate (HCA) suppresses food intake and body weight regain in male rats after substantial body weight loss. However, it is not known whether Hydroxycitric acid also affects the respiration quotient (RQ), energy expenditure (EE), and glucose tolerance in this animal model. Twenty-four male rats (initial body weight, 378 +/- 3 g) were fed restrictively (10 g/d) for 10 d and then given ad libitum access to a high-glucose diet supplemented with 3% HCA for 6 d. Controls received the same diet without the supplement. RQ and EE were measured during ad libitum days 1, 2, and 6. An oral glucose tolerance test was performed on ad libitum day 4 or 5. HCA decreased RQ and EE during ad libitum days 1 and 2. In all probability, these findings reflect a decrease in de novo lipogenesis. On ad libitum day 6, RQ and EE did not differ between treatment groups. Hydroxycitric acid suppressed food intake during the first 3 d ad libitum, but overall body weight regain was not decreased in the Hydroxycitric acid group. The oral glucose tolerance test showed that Hydroxycitric acid significantly decreased the increase in plasma glucose from baseline (Deltaglucose) and tended to decrease the area under the curve for glucose. Deltainsulin and area under the curve for insulin did not differ between groups. CONCLUSIONS: These results indicate that, in this animal model, Hydroxycitric acid suppresses de novo lipogenesis. Moreover, Hydroxycitric acid may improve glucose tolerance.

Safety assessment of (-)-hydroxycitric acid and Super CitriMax, a novel calcium/potassium salt.
Food Chem Toxicol. 2004 Sep;42(9):1513-29. Soni MG, Burdock GA, Preuss HG, Stohs SJ, Ohia SE, Bagchi D.
Burdock Group, 780 US Highway 1, Suite 300, Vero Beach, FL
Super CitriMax, a novel calcium/potassium-HCA extract (HCA-SX), is considerably more soluble and bioavailable than calcium-based HCA ingredients. Acute oral toxicity studies in animals demonstrate that CitriMax (50% HCA as calcium salt) has a low acute oral toxicity. In a subchronic study in rats, the gavage administration of HCA-SX at doses up to 2500 mg/kg/day for a period of 90 days caused a significant decrease in body weight and reduction in feed consumption without any adverse effects. The structure, mechanism of action, long history of use of HCA and other toxicity studies indicate that HCA-SX is unlikely to cause reproductive or developmental effects. HCA-SX was not mutagenic in the presence or absence of metabolic activation in Ames genotoxicity assays in strains TA98 and TA102. HCA-SX-induced increases in number of revertants in other strains (TA100 and TA1535 in the absence of metabolic activation and in strain TA1537 in the presence of metabolic activation) but these were not considered as biologically indicative of a mutagenic effect. In several, placebo-controlled, double-blind trials employing up to 2800 mg/day HCA, no treatment-related adverse effects were reported. There is sufficient qualitative and quantitative scientific evidence, including animal and human data suggesting that intake of HCA at levels up to 2800 mg/day is safe for human consumption.

Physico-chemical properties of a novel (-)-hydroxycitric acid extract and its effect on body weight, selected organ weights, hepatic lipid peroxidation and DNA fragmentation, hematology and clinical chemistry, and histopathological changes over a period of 90 days.
Mol Cell Biochem. 2004 May;260(1-2):171-86. Shara M, Ohia SE, Schmidt RE, Yasmin T, Zardetto-Smith A, Kincaid A, Bagchi M, Chatterjee A, Bagchi D, Stohs SJ. Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Creighton University Medical Center, Omaha, NE
Garcinia cambogia-derived (-)- hydroxycitric acid (HCA) is a popular and natural supplement for weight management. Hydroxycitric acidis a competitive inhibitor of the enzyme ATP citrate lyase, which catalyzes the conversion of citrate and coenzyme A to oxaloacetate and acetyl coenzyme A (acetyl CoA) in the cytosol. Acetyl CoA is used in the synthesis of fatty acids, cholesterol and triglycerides, and in the synthesis of acetylcholine in the central nervous system. Studies have demonstrated the efficacy of a novel 60% calcium-potassium salt of hydroxycitric acid derived from Garcinia cambogia (HCA-SX, Super CitriMax) in weight management. Results have shown that HCA-SX promotes fat oxidation, enhances serotonin release and availability in the brain cortex, normalizes lipid profiles, and lowers serum leptin levels in obese subjects. Acute oral, acute dermal, primary dermal irritation and primary eye irritation toxicity, as well as Ames bacterial reverse mutation studies and mouse lymphoma tests have demonstrated the safety of HCA-SX. However, no detailed long-term safety of HCA-SX or any other hydroxycitric acid extract has been previously assessed. We evaluated the dose- and time-dependent effects of HCA-SX in Sprague-Dawley rats on body weight, selected organ weights, hepatic lipid peroxidation and DNA fragmentation, hematology and clinical chemistry over a period of 90 days. Taken together, these results show that 90 day treatment of HCA-SX results in a reduction in body weight, and does not cause any changes in major organs or in hematology, clinical chemistry, and histopathology.

Effects of a natural extract of (-)-hydroxycitric acid (HCA-SX) and a combination of HCA-SX plus niacin-bound chromium and Gymnema sylvestre extract on weight loss.
Diabetes Obes Metab. 2004 May;6(3):171-80. Preuss HG, Bagchi D, Bagchi M, Rao CV, Dey DK, Satyanarayana S.
Department of Physiology and Biophysics, Georgetown University Medical Center, Georgetown, Washington, DC 20057
The efficacy of optimal doses of highly bioavailable (-)-  hydroxycitric acid alone and in combination with niacin-bound chromium (NBC) and a standardized Gymnema sylvestre extract (GSE) on weight loss in moderately obese subjects was evaluated by monitoring changes in body weight, body mass index (BMI), appetite, lipid profiles, serum leptin and excretion of urinary fat metabolites. hydroxycitric acid has been shown to reduce appetite, inhibit fat synthesis and decrease body weight without stimulating the central nervous system. NBC has demonstrated its ability to maintain healthy insulin levels, while GSE has been shown to regulate weight loss and blood sugar levels. A randomized, double-blind, placebo-controlled human study was conducted in Elluru, India for 8 weeks in 60 moderately obese subjects (ages 21-50, BMI >26 kg/m(2)). Subjects were randomly divided into three groups. Group A was administered hydroxycitric acid 4667 mg, group B was administered a combination of hydroxycitric acid 4667 mg, NBC 4 mg and GSE 400 mg, while group C was given placebo daily in three equally divided doses 30-60 min before meals. All subjects received a 2000 kcal diet/day and participated in supervised walking. At the end of 8 weeks, body weight and BMI decreased by 5-6% in both groups A and B. Food intake, total cholesterol, low-density lipoproteins, triglycerides and serum leptin levels were significantly reduced in both groups, while high-density lipoprotein levels and excretion of urinary fat metabolites increased in both groups. A marginal or non-significant effect was observed in all parameters in group C. The present study shows that optimal doses of HCA-SX and, to a greater degree, the combination of hydroxycitric acid, NBC and GSE can serve as an effective and safe weight-loss formula that can facilitate a reduction in excess body weight and BMI, while promoting healthy blood lipid levels.

Hydroxycitric acid HCA supplement questions
Q. I have type 2 diabetes. In addition to my prescription treatment, I have added some natural products. The hydroxycitric acid HCA product helped me feel a lot better. However, after about a year, I became allergic (itching). I suspect that my allergy is due to plant extracts that accompany the HCA.
   A. It is often a good idea to take a break from most supplements in order to avoid tolerance, allergy, or excess exposure.

Q. When I discovered that I had type 2 Diabetes I started taking an hydroxycitric acid HCA supplement. I could not believe how good I felt on the supplement. However, after several months, I started itching and found that I had developed an allergy to something in the supplement. I tried some other brands…they all employed a form of hydroxycitric acid HCA that was extracted from Garcinia Cambogia. I found that I had an allergic reaction to all of them. I think that my allergy may be due to an impurity that extracts along with the HCA. I really doubt that I could be allergic to hydroxycitric acid Is there an alternate plant source or a chemically pure form that I could try? What do you think?
   A. It is possible that hydroxycitric acid caused the itching but we cannot be sure. We have not seen long term trials with this supplement given for many months or years. We are not aware of another source of hydroxycitric acid as of July 2008.

Hydroxycitric acid HCA