The Skinny on Garcinia Research
What is it?
Garcinia is a group of over 200 plant species in which Garcinia cambogia, Garcinia mangostana (aka mangosteen), and Garcinia kola are among the most commonly known. Garcinia cambogia, referred to here as Garcinia, is also known as Garcinia gummi-gutta, Gambooge, and Malabar tamarind [not to be confused with the legume-looking brown tamarind (Tamarindus indica)].
Garcinia is a small-to-medium-sized fruit that varies in colour. Its rind can contain up to 30% (-) hydroxycitric acid (HCA), the enzyme responsible for many of its proposed health benefits. The rind has a sour and slightly acidic taste, similar to tamarind, and is used extensively in India and Southeast Asia as a culinary flavoring & coloring agent e.g. in curries. Garcinia is also used in Ayurvedic medicine to help prevent the formation of gas after eating.
How Does it Work?
Researchers have proposed several mechanisms by which HCA may work. The most widely known mechanism is its inhibition of the enzyme adenosine triphosphate-citrate-lyase. This enzyme prevents the formation of acetyl coeyzme A and oxaloacetate, which are the primary building blocks in fatty acid and cholesterol synthesis [3, 4].
Another proposed mechanism is that HCA causes an increase in the release or availability of serotonin, a hormone involved in appetite suppression and mood regulation [1, 2]. Garcina may also inhibit pancreatic amylase and intestinal glucosidase enzymes, which may lead to decreased carbohydrate metabolism [1, 3].
Proposed Health Benefits & Clinical Evidence
Much of today’s buzz surrounds Garcinia’s proposed ability to promote weight loss, reduce fat mass, and lower lipids [2, 5]. Researchers are also studying Garcinia’s effect on exercise performance, cancer, diabetes, GI disorders, and increasing red blood cell count . Much of the controversy has to do with inconsistent evidence for effectiveness. Some researchers have found that patients who took a Garcinia-active extract lost more weight than patients who took a placebo, even if they did not follow a reduced-calorie diet . Results of the study by Hayamizu et al. indicate that Garcinia reduces abdominal fat accumulation, regardless of sex, in obese patients . Studies by other researchers, however, have not yielded the same results. In the trial by Heymsfield et al., patients did not experience significant weight or fat loss . Furthermore, several studies found no effect on satiety. The meta-analysis by Onakpoya et al. concluded that HCA may offer only a small weight loss in the short term and questioned the clinical relevance of the results .
Garcinia on the Market
In clinical trials, researchers used various dosing protocols for Garcinia. One treatment involved the active Garcinia extract (50% HCA), taken 3 times daily as two 500 mg caplets 30 minutes before meal ingestion for a total dose of 3000 mg daily . Other treatments included 750 mg up to 4667 mg capsules or tablets daily (in divided doses) taken 30 – 60 minutes before meals [2, 6,7].
Several trials used Super CitriMax® (HCA-SX), which formulates HCA as a calcium/potassium salt, making the supplement more soluble . Since then several CitriMax products have come on the market ranging from Mega CitriMax to Super Pure CitriMax. Each product, usually containing 60% HCA, has slightly different dosing instructions but generally suggest a dose of 1500 mg/day.
Concerns & Pharmacy Relevance
The main adverse reaction noted by participants of Garcinia trials was gastrointestinal effects like nausea and diarrhea . More recently, case reports have been published regarding hepatitis caused by Garcinia extracts [8,9]. Because of Garcinia’s effect on cholesterol, persons who are taking a statin, e.g. Crestor/rosuvastatin, should exercise more caution due to the risk of rhabdomyolysis, a potentially serious muscle condition. Additionally, persons with diabetes should be mindful of the potential for hypoglycemia. Garcinia may also pose a concern for persons who are sensitive to or take medication or supplements containing iron, potassium, calcium, and serotonin.
The media has been promoting Garcinia as a supplement for anyone looking to shed pounds; however, most of the studies involved patients who were either overweight or obese. Although it should make sense that if Garcinia helps an overweight person lose weight then it should help a slimmer person, body chemistry is not so straightforward. Someone who has more weight to lose has a different metabolism and fat mass and Garcinia may very well affect them differently.
Another concern is that many of the trials are still in the animal study phase. Studies involving humans have had a small number of participants, have only been done in the short term (12 weeks or less), and for the most part have not been well designed. Additionally, many of the studies are outdated. Garcinia doses have not been standardized and have varied significantly in clinical trials, so I am surprised by the fact that companies have already marketed “the right dose”. Finally, Garcinia may interact with some medications, and therefore is not safe for everyone as some experts claim.
Unfortunately I’m still skeptical about Garcinia. The internet is awash with persons who say Garcinia has worked for them, even though most admit to doing a lower-calorie diet and exercise. I also don’t know what would happen once a person stops taking the supplement. All in all, I can’t recommend Garcinia. I’ll pass until there is more research (and research in humans, too!)
Heymsfield SB, Allison DB, Vasselli JR, et al. Garcinia cambogia (hydroxycitric acid) as a potential antiobesity agent – a randomized controlled trial. JAMA. 1998;280(18):1596-1600. doi:10.1001/jama.280.18.1596
Onakpoya I, Hung SK, Perry R, et al. The Use of Garcinia Extract (Hydroxycitric Acid) as a Weight loss Supplement: A Systematic Review and Meta-Analysis of Randomised Clinical Trials. J Obes. 2011. doi: 10.1155/2011/509038
Soni MG, Burdock GA, Preuss HG, et al. Safety assessment of (-)-hydroxycitric acid and Super CitriMax, a novel calcium/potassium salt. Food Chem Toxicol 2004;42(9):1513-1529.
Saper RB, Eisenberg DM, Phillips RS. Common dietary supplements for weight loss. Am Fam Physician. 2004;1;70(9):1731-1738.
Márquez F, Babio N, Bulló M, Salas-Salvadó J. Evaluation of the safety and efficacy of hydroxycitric acid or Garcinia cambogia extracts in humans. Crit Rev Food Sci Nutr. 2012;52(7):585-94. doi: 10.1080/10408398.2010.500551.
Hayamizu K, Ishii Y, Kaneko I, et al. Effects of garcinia cambogia (Hydroxycitic Acid) on visceral fat accumulation: a double-blind, randomized, placebo-controlled trial. Current Therapeutic Research. 2003;64(8):551-567.
Preuss HG, Bagchi D, Bagchi M, et al. 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;6(3):171-80
Crescioli G, Lombardi N, Bettiol A, et al. Acute liver injury following Garcinia cambogia weight-loss supplementation: case series and literature review. Intern Emerg Med. 2018;(6):857-872. doi: 10.1007/s11739-018-1880-4.