Hydroxycitric acid (HCA), a derivative of citric acid, is found primarily in a small, sweet, purple fruit called the Malabar tamarind or, as it is most commonly called, Garcinia cambogia. Test tube and animal research suggests that HCA may be helpful in weight loss because of its effects on metabolism. However, studies in humans have found mixed results.

HCA is not an essential nutrient. The Malabar tamarind is the only practical source of this supplement.