What is Garcinia cambogia?
Garcinia gummi-gutta is a subtropical species of Garcinia native to Indonesia. The fruit rind of Garcinia gummi-gutta is most commonly known as Garcinia cambogia. Other common names include gambooge, brindleberry, brindall berry, Malabar tamarind, assam fruit, vadakkan puli and kudam puli.
Garcinia has been used for centuries in Asian countries for culinary purposes as a condiment and flavoring agent in place of tamarind or lemon, and to make meals more filling. Garcinia, or more specifically Garcinia cambogia, Garcinia atroviridis, and Garcinia indica have been found to contain large amounts of hydroxycitric acid (HCA). Another plant species with high concentrations of HCA is Hibiscus subdariffa.
There are multiple chemical forms of HCA with the (-)-hydroxycitric acid form being the one found in Garciia extracts.
Garcinia has been widely used as an anti-obesity herbal supplement for many decades. HCA has been shown to be able to inhibit the synthesis of fatty acids (a process referred to as lipogenesis) from carbohydrate (predominantly glucose) and certain amino acids. HCA inhibits fatty acid synthesis by interfering with an ezyme in the pathway called ATP citrate lyase, ACL. The interference in carbohydrate conversion to fat by HCA induces the body to metabolize the excess carbohydrates as well as promoting glucose storage in glycogen, both of which in turn may play a part in suppressing the appetite. HCA has also been shown to suppress appetite by increasing the release of serotonin which is a neurotransmitter that functions, in part, in the modulation of feeding behavior and appetite control.
However, despite many research publications addressing the role of HCA as an anti-obesity supplement, which have been carried out in laboratory animals, its potential contribution as a weight loss agent in humans has been controversial. In addition, most human studies carried out so far have concluded that the safety and efficacy of HCA is questionable.
How Does Hydroxycitric acid (HCA) Work?
The various chemical forms of HCA has been shown to exhibit multiple effects on metabolic processes with the consequences being the potential for weight loss and improved glucose tolerance, especially in overweight and obese individuals with type 2 diabetes. The primary metabolic process inhibited by HCA is the one responsible for the diversion of excees carbon atom in the diet into fatty acids (fat) for storage in fat tissue (adipose tissue). The enzyme inhibited is called ATP citrate lyase and it hydrolyzes citric acid into acetyl-CoA and oxaloacetic acid. Acetyl-CoA is the required precursor for fatt acid synthesis, which occurs in all cells but at the highest levels in the liver. The primary source of the citrate for this reaction is acetyl-CoA itself derived from the metabolism of carbohydrates and also from certain amino acids. Thus, excess carbon consumption in the form of carbohydrates (sugars) or proteins will lead to fat storage and weight gain. Chemical forms of HCA have also been shown to inhibit certain digestive enzymes which results in a reduction in the ability to digest and absorb carbohydrates. This latter effect can, therefore, contribute to a reduction in blood glucose which is of great benefit in type 2 diabetes.
Is HCA Really an Anti-Obesity Agent?
Recent meta-analysis comparing the data from multiple trials have suggested that consumption of Garcinia cambogia extracts or HCA supplementation produced only minimal short-term weight-loss, and the clinical relevance remains yet to definitively established. Most randomized double-blind placebo-controlled trials of the efficacy of Garcinia in weight loss have produced, at best, equivocal data. The largest and most rigorous randomized double-blind placebo-controlled trials to date found no significant difference in weight-loss when comparing participants who consumed HCA supplements and those who received placebo supplementation.
Of particular concern to the use so-called "pure" Garcinia cambogia or HCA supplements is that they are sold with no verificaiton of purity. In addition there are various HCA salts that one can obtain in dietary supplements, including calcium, magnesium, potassium, as well as mixtures of these. When these different HCA slats are tested for efficacy in experimental animals they exhibit different properties with some, but not all, improving glucose tolerance. Several cases of liver failure have been reported in the medical literature in patients who have consumed Garcinia cambogia extracts or HCA supplements, and in one case it resulted in the need for liver transplantation for survival. Even so there have been reports that have demonstrated that HCA does not exhibit liver toxicity, although these reports involve studies in laboratory animals.
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Last modified: February 22, 2017