Garcinia for Weight Loss: Modest Effect With Safety Caveats

Gayle N. Scott, PharmD

Disclosures

November 21, 2017

Question

Is garcinia a safe and effective dietary supplement for patients hoping to lose weight?

Response from Gayle N. Scott, PharmD
Assistant Professor, Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia

Garcinia became a rock star in the dietary supplement world after a 2012 endorsement by television host Dr Mehmet Oz, who called it a "revolutionary fat buster." (The endorsement was removed from the Dr Oz website following a Senate hearing on questionable weight loss products.[1]) Described as the "Oz effect," Dr Oz's endorsement of a dietary supplement usually has a substantial impact on product sales,[2,3,4] even when scientific evidence is not favorable.

Garcinia (Garcinia gummi-gutta, formerly known as Garcinia cambogia) is a small- to medium-sized tree native to India, Nepal, and Sri Lanka. Other common names include brindleberry, Malabar tamarind, and kudam puli (pot tamarind).[2] In the United States, garcinia products derived from the fruit are available as dietary supplements that are often promoted for weight loss. The major organic acid in the fruit is hydroxycitric acid (HCA), which is thought to account for the pharmacologic effects of garcinia. Animal research suggests that HCA may inhibit enzymes that synthesize fatty acids.[2]

A 2011 meta-analysis[3] reviewed nine clinical trials of garcinia extract (HCA) for weight loss; little research has been published since. The meta-analysis revealed a small yet statistically significant difference in weight loss in favor of HCA over placebo (mean difference: -0.88 kg; 95% confidence interval, -1.75 to -0.00, P < .05). This corresponds to about a 1% body weight loss in the HCA group compared with placebo,[3] in contrast to an average 3% weight loss in patients taking orlistat compared with placebo.[4] The study design showed considerable heterogeneity, and the duration of treatment and the dose of HCA used in the different trials varied widely. Two of the studies lasted 12 weeks, and the rest lasted 2-8 weeks. The persistence of weight loss and long-term safety with garcinia are unknown.[3]

The most common adverse effects reported were headache, nausea, and upper respiratory and gastrointestinal tract symptoms, but most of the trials reported no significant differences in adverse events between HCA and placebo.[3]

However, multiple case reports have implicated HCA-containing products in serious adverse reactions.[5] Hepatitis and hepatic failure requiring transplantation have been described in several case reports.[6,7,8] Serotonin toxicity in a 35-year-old woman who was also taking escitalopram has been reported.[9] Animal research suggests that HCA may increase serotonin levels.[10] Mania in patients with and without a history of psychiatric illness has been reported.[11]

The dietary supplements associated with these adverse effects often contained multiple ingredients, including HCA. For example, previous formulations of the combination weight loss product Hydroxycut® contained HCA along with various other supplements. Hydroxycut products that contained HCA have been associated with mania,[12] rhabdomyolysis,[13] hepatotoxicity, and other adverse effects.[14,15] Whether HCA or another Hydroxycut ingredient was responsible for the toxicities is unknown.[5]

Currently, not enough research is available to recommend garcinia or HCA-containing products for weight loss.

Currently, not enough research is available to recommend garcinia or HCA-containing products for weight loss. If garcinia or HCA-containing products are beneficial, the effects appear to be modest. Rare but serious adverse effects have been reported, and long-term toxicity is unknown. No published studies have lasted beyond 3 months.

Patients taking medications that affect serotonin (eg, dextromethorphan, selective serotonin reuptake inhibitors, tramadol) should avoid HCA. Given the reports of hepatic toxicity, patients with liver disease or patients taking potentially hepatotoxic drugs (eg, carbamazepine, isoniazid) should not take HCA.

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