Garcinia Cambogia: Benefits, Forms, Dosing, and Side Effects

Table of Contents

• Current evidence position
• Key safety points
• Brad's videos on this topic
• Overview
• Forms and Bioavailability
• Evidence for Benefits
• Recommended Dosing
• Safety and Side Effects
• Drug Interactions
• Dietary Sources
• References

Current evidence position

Brad has not made a video on this topic; this is a summary of the evidence, not his view. NIH's complementary health center says it is unclear whether garcinia cambogia products help with weight loss: some evidence suggests a modest effect, while other evidence shows none ^[2]. In a 2011 meta-analysis, garcinia extract providing 1,000 to 2,800 mg a day of hydroxycitric acid (HCA) for 2 to 12 weeks gave a mean of 0.88 kg more weight loss than placebo, but the effect was no longer significant in the two rigorously designed trials ^[30]. Case reports link garcinia products to severe liver injury, including liver failure that needed a transplant and death, and to serotonin toxicity in a patient also taking SSRI antidepressants ^{[7, 26, 30]}. All trials have been short, so long-term safety is unknown; anyone who takes medicines should talk to a doctor first, and with little known about pregnancy and breastfeeding, garcinia is best avoided then ^{[2, 30]}.

Brad's videos on this topic

None yet.

1. Overview

Garcinia cambogia (Garcinia gummi-gutta, also called Malabar tamarind or brindle berry) is a tree native to India and Southeast Asia, where it is commonly found in evergreen forests ^[2]. The fruit has been used as a tea in folk medicine for inflammation and stomach complaints, and the fruit rind has a history of traditional use as a food preservative ^[2].

The fruit rind contains hydroxycitric acid (HCA), the compound studied for its effect on appetite and body weight ^[2]. HCA competitively inhibits ATP-citrate lyase, an enzyme that may play an essential role in making new fat (de novo lipogenesis) ^[13].

Garcinia products with HCA are promoted for appetite control and weight loss ^[2]. The trial evidence is mixed, and numerous reports of liver toxicity have raised serious safety concerns ^{[2, 26]}.

Studies in rats have found that garcinia suppresses food intake and inhibits weight gain ^[30]. In humans, the evidence is conflicting, and any effects appear small ^[30]. The U.S. National Center for Complementary and Integrative Health (NCCIH) states plainly: "It's unclear whether garcinia cambogia products help with weight loss" ^[2].

The NIH LiverTox database notes that weight-loss products labeled as containing garcinia have been linked to acute liver injury that can be severe and even fatal ^[26].

This article reviews the clinical evidence for garcinia cambogia, including weight-loss trials, kidney stone research, safety data, drug interactions and doses.

2. Forms and Bioavailability

HCA Chemistry and Stability

HCA in weight-loss supplements is typically bound to calcium, which Downs and colleagues describe as a poorly soluble (less than 50%) and less bioavailable form ^[12]. By their account, a calcium-potassium salt of HCA (HCA-SX, sold as Super CitriMax) is completely water soluble and bioavailable ^[12].

Absorption Characteristics

Human data on HCA absorption are sparse:

• Time course: In four people who took 2 g of HCA, plasma HCA ranged from 0.8 micrograms/mL at 30 minutes to 8.4 micrograms/mL at 2 hours. The authors concluded that HCA is absorbed but present in small quantities in human plasma ^[11].
• Food effect: Preuss and colleagues' overview of the maker's own HCA-SX studies reported that it was better absorbed on an empty stomach ^[33].

Mineral Content of Garcinia Supplements

Because HCA is bound to minerals, large daily doses can supply meaningful amounts of them. Downs and colleagues report that 4,500 mg a day of HCA-SX, taken in three doses, provides 495 mg of calcium (49.5% of the reference daily intake) and 720 mg of potassium (15% of the reference daily intake) ^[12]. People taking other mineral supplements, or medicines affected by calcium or potassium intake, should count this contribution.

Extract Standardization

Labels do not always match what is in the product. A 2022 analysis of 18 garcinia supplements found that the measured HCA content differed from the declared amount in 33% of samples, and some contained compounds not found in the fruit and not declared on the label ^[29].

Comparison Table: Garcinia Extract Forms

Multi-Ingredient Products: A Caution

NCCIH says it may be unsafe to consume garcinia cambogia products, including multi-ingredient products that contain garcinia extract ^[2]. In most published liver-toxicity cases, the products also contained other botanical ingredients and minerals, so the toxicity cannot be definitively attributed to garcinia ^[30].

3. Evidence for Benefits

Weight Loss

Whether garcinia cambogia helps weight loss is uncertain. Rat studies show reduced food intake and weight gain, but human trials have produced conflicting results ^[30].

Early Clinical Trials

Heymsfield et al. (1998): no benefit over placebo

This 12-week randomized, double-blind trial gave overweight men and women (mean BMI approximately 32 kg/m2) either garcinia providing 1,500 mg a day of HCA or placebo, with a high-fiber, low-energy diet; 135 people were randomized ^[13]. Participants took 1,000 mg 30 minutes before every meal ^[30].

Both groups lost weight, but the difference between them was not significant (3.2 kg with HCA vs 4.1 kg with placebo), and HCA did not change the loss of body fat ^[13].

Mattes and Bormann (2000): more weight loss, no change in appetite

In this 12-week double-blind trial, 89 mildly overweight women on a 1,200 kcal diet took 800 mg of garcinia 30-60 minutes before meals, 2.4 g a day (1,200 mg of HCA), or placebo ^[30]. The garcinia group lost more weight (3.7 kg vs 2.4 kg) ^[30]. HCA had no effect on appetite, and the authors concluded that the study does not support a satiety effect ^[15].

Kovacs et al. (2001): no effect on satiety or weight in men

A 2-week crossover trial in 11 overweight men compared 500 mg of HCA, 500 mg of HCA with 3 g of medium-chain triglycerides, and no supplement ^[16]. Weight fell in every period, but HCA did not increase satiety, fat oxidation, energy expenditure or weight loss compared with placebo ^[16].

Later Clinical Trials

Westerterp-Plantenga and Kovacs (2002): lower food intake, no clear weight change

In this 6-week single-blind crossover trial, 12 men and 12 women who were overweight drank 100 ml of tomato juice with 300 mg of HCA, or plain tomato juice, three times daily for 2 weeks each ^[10]. With HCA, 24-hour energy intake fell by 15 to 30% compared with placebo, appetite ratings did not change, and body weight tended to decrease (P=0.1) ^[10].

Vasques et al. (2014): lower triglycerides, no weight change

Obese women on dietary control took 2.4 g of garcinia extract (50% HCA, 800 mg three times a day) or placebo for 60 days; 30 were treated and 13 were controls ^[17]:

• Triglycerides: Triglycerides fell significantly in the garcinia group (p = 0.0002), and the change differed from placebo (p = 0.04) ^[17].
• No weight effect: There was no significant change in weight, BMI, waist-hip ratio or body fat ^[17].
• No lipid panel improvement: Total cholesterol, HDL and LDL did not change significantly ^[17].
• No hormonal effect: Leptin and insulin levels did not change significantly ^[17].

Systematic Reviews and Meta-Analyses

Golzarand et al. (2020): dose-response meta-analysis

This meta-analysis of eight trials (530 subjects) found that garcinia reduced weight by 1.34 kg (95% CI 0.07 to 2.62) compared with placebo, with falls in BMI, body fat percentage and waist size ^[4]. An earlier meta-analysis that pooled nine trials found a small difference of -0.88 kg (95% CI -1.75 to -0.00), of uncertain clinical relevance ^[35].

Maunder et al. (2020): herbal medicines for weight loss

This review of 54 randomized placebo-controlled trials of herbal medicines found no effect on weight for garcinia cambogia, and concluded that the evidence is insufficient to recommend any of the herbal medicines it studied for weight loss ^[5].

Summary of Weight Loss Evidence

Interpretation

Pooled trials suggest that garcinia extracts can cause a small, short-term weight loss of uncertain clinical relevance ^[35]. Several patterns emerge from the clinical data:

1. Effects on appetite and body weight diverge: one trial cut food intake without a clear weight change, and another found more weight loss without any change in appetite ^{[10, 15]}.
2. The magnitude of any benefit is small: the pooled differences from placebo in both meta-analyses were small ^{[4, 35]}.
3. Trials were short: long-term effects and safety are unknown ^[30].

Kidney Stones

Laboratory and animal studies suggest that HCA may stop calcium oxalate crystals from forming and may help dissolve them ^{[18, 19, 20]}. Calcium oxalate monohydrate is the principal component of human kidney stones ^[18].

Mechanism: A study published in Nature found that hydroxycitrate binds to calcium oxalate crystal surfaces and, under specific conditions, makes the crystal dissolve rather than only slowing its growth ^[18].

Preclinical evidence:

• Chung et al. (2016): In human urine tested in the laboratory, hydroxycitrate inhibited calcium oxalate crystal formation as well as citrate did, and people without kidney stones who took HCA excreted substantial amounts in their urine ^[18].
• Fan et al. (2020): Garcinia extract dissolved calcium oxalate crystals in fruit-fly kidney stone models ^[19].
• Yang et al. (2022): In a rat kidney stone model, HCA reduced calcium oxalate crystal build-up and kidney damage, and was better than citrate at inhibiting crystal build-up ^[20].

Human evidence:

One randomized trial in people has tested a supplement containing HCA:

• Cano García et al. (2023): In 81 patients with calcium stones having shock wave lithotripsy, every patient given FagolitosPlus, a supplement that combines HCA with magnesium, vitamin B6, zinc and vitamin A, had stone fragmentation, while 17% of those on placebo did not (p = 0.03) ^[32].

Assessment: The laboratory and animal results are promising, and one trial suggests a combination supplement containing HCA may help calcium stone fragmentation with shock wave treatment, though it cannot show how much HCA itself contributed ^[32]. The authors of the Nature study concluded that their findings support exploring HCA as an alternative to citrate for treating kidney stones ^[18].

Serotonin Modulation

In rat brain tissue, an HCA extract (HCA-SX, Super CitriMax) inhibited serotonin uptake: at 300 micromolar it caused a 20% decrease, compared with 30% for the antidepressants fluoxetine plus clomipramine ^[34]. In an 8-week study in 60 volunteers given 4,666.7 mg of HCA-SX a day (2,800 mg of HCA), serum serotonin levels rose significantly ^[33]. This activity may matter for mood and for interactions with SSRI antidepressants (see Drug Interactions section) ^{[2, 22]}.

Lipid Effects

Beyond the triglyceride reduction found by Vasques et al. (2014), the effects of garcinia on blood lipids have been inconsistent. That trial found no significant change in total cholesterol, HDL or LDL ^[17]. Preuss and colleagues' overview of the maker's own HCA-SX studies reported lower total cholesterol, LDL and triglycerides and higher HDL in an 8-week study ^[33].

4. Recommended Dosing

Doses Used in Clinical Trials

Clinical trials of garcinia cambogia have used a range of doses, expressed as extract weight, HCA content or both:

Timing and Administration

• Empty stomach: Preuss and colleagues' overview of the maker's own HCA-SX studies reported that it was better absorbed without food ^[33].
• Before meals: Several trials gave it 30-60 min before meals ^{[15, 33]}.
• Divided doses: Several trials gave the daily amount in three doses ^{[10, 17, 33]}.

Typical Supplement Doses

No dose has proven reliably effective; the trials pooled in a 2011 meta-analysis used 1,000 to 2,800 mg a day of HCA ^[30].

Important Dosing Considerations

1. Elemental HCA vs. extract weight: Supplement labels may list either the weight of the total Garcinia extract or the weight of HCA specifically. A product listing "1,000 mg Garcinia cambogia (50% HCA)" provides 500 mg of HCA per serving.
2. No established effective dose: Given the inconsistent clinical evidence, there is no well-established "effective dose" for any specific health outcome ^[2].
3. No long-term safety data at any dose: Trials have lasted 2 to 12 weeks, and long-term safety is unknown ^[30].

5. Safety and Side Effects

Common Side Effects

Side effects reported with garcinia and HCA include ^{[2, 30]}:

• Headache
• Nausea
• Diarrhea and other gastrointestinal symptoms
• Upper respiratory tract symptoms

These are generally mild ^[30]. In one trial within a meta-analysis, gastrointestinal adverse events were twice as common with HCA as with placebo ^[35].

Liver Toxicity — The Primary Safety Concern

The most serious safety concern with garcinia cambogia is liver injury. The NIH weight-loss fact sheet cites reports of 10 cases of liver toxicity in people taking products containing garcinia, with one death and two liver transplants, though most of these products contained other botanicals and minerals as well ^[30]. LiverTox notes that this liver injury can be severe and even fatal ^[26]. If you take garcinia, stop it and see your doctor if you get abdominal pain, dark urine, tiredness or yellow skin or eyes. If yellow skin or eyes come with confusion, unusual drowsiness, or easy bleeding or bruising, call your local emergency number (111 in NZ, 000 in Australia, 911 in the US, 999 in the UK) or go to the emergency department.

Case Reports

Case 1: Liver transplant (Lunsford et al., 2016)

Lunsford and colleagues reported what they described as the first known case of fulminant liver failure associated with garcinia; the patient needed a liver transplant ^[7].

Case 2: Acute hepatitis that returned on rechallenge (Sharma et al., 2018)

A 57-year-old woman with no previous liver disease developed acute hepatitis while taking garcinia extract for weight loss. It resolved after she stopped and came back when she took it again ^[8].

Case 3: Acute liver failure (Yousaf et al., 2019)

A 21-year-old woman who had used garcinia for 4 weeks presented with a week of abdominal pain, nausea, vomiting and loss of appetite. Tests showed acute liver failure, and no other cause was found ^[9].

Case 4: Liver transplant after long-term use (Ferreira et al., 2020)

A 26-year-old woman who had taken garcinia for 7 months developed subacute liver failure and needed a liver transplant ^[25].

Systematic Reviews of Liver Injury

Crescioli et al. (2018): This case series described four women who developed acute liver failure while taking garcinia extract for weight loss, with a review of published cases ^[23].

Ballotin et al. (2021): This review of 936 published cases of herb-induced liver injury listed garcinia cambogia among the most commonly reported products ^[24]. Across all herbs, most people recovered fully (82.8%), but 6.6% needed a liver transplant and 10.4% died ^[24].

Regulatory Response

Health agencies have responded to the liver reports:

• United States (FDA): Lunsford and colleagues note that HCA is also found in weight-loss supplements that the FDA banned in 2009 for liver toxicity ^[7]. The LiverTox database maintained by the National Institute of Diabetes and Digestive and Kidney Diseases catalogues the hepatotoxicity evidence ^[26].
• NCCIH assessment: The NIH's National Center for Complementary and Integrative Health states: "It may be unsafe to consume garcinia cambogia products, including multi-ingredient products containing garcinia cambogia extract. Several cases of liver damage have been reported. Some of these cases were severe, but this appears to be uncommon" ^[2].

Psychiatric Effects: Mania

The NIH fact sheet cites three cases of mania with supplements containing garcinia, which might have been caused by the serotonergic activity of HCA ^{[27, 30]}. Symptoms included grandiosity (an unrealistic sense of superiority), irritability, pressured speech and a decreased need for sleep ^[30]. Mania, sometimes with psychosis, has been reported, including in people with no history of bipolar disorder ^[38]. A 2018 systematic review counted four garcinia case reports, and three of those patients had a past history of bipolar disorder ^[37]. People who have had mania or have bipolar disorder should talk to their doctor before taking garcinia ^[37].

Testicular Toxicity (Animal Data)

In a study that fed young, genetically obese male rats garcinia extract for 92 or 93 days, only the highest dose suppressed fat build-up, while diets providing 778 and 1244 mg of HCA per kg of body weight a day caused marked testicular atrophy and toxicity ^[28]. Diets providing 389 mg of HCA per kg of body weight a day or less did not, and the authors set this as the no-observed-adverse-effect level ^[28]. Whether this applies to people at usual doses is unknown.

Pregnancy and Breastfeeding

Little is known about whether it is safe to use Garcinia cambogia during pregnancy or while breastfeeding ^[2]. With little known and the liver reports, it is best avoided.

6. Drug Interactions

SSRI Antidepressants — Serotonin Toxicity Risk

The most important interaction concern involves SSRI (selective serotonin reuptake inhibitor) antidepressants. NCCIH reports interactions between garcinia cambogia and some drugs that affect serotonin ^[2].

Case report (Lopez et al., 2014): A woman taking a garcinia supplement every day developed serotonin toxicity while on escitalopram, which was then stopped. After 2 weeks without any antidepressant she started sertraline while still taking garcinia, and serotonin toxicity returned ^[22].

Mechanism: In rat brain tissue, HCA-SX inhibited serotonin uptake much as SSRIs do, and serum serotonin rose in an 8-week human study ^{[33, 34]}. Because SSRIs also raise serotonin, the combination may push serotonin activity too high.

Clinical implication: Interactions with drugs that affect serotonin have been reported ^{[2, 22]}. If you take an SSRI or SNRI antidepressant (such as escitalopram, sertraline, fluoxetine or venlafaxine) or another drug that affects serotonin, do not combine it with garcinia unless your doctor agrees. Serotonin syndrome can be deadly; its features include tremor, overactive reflexes, a racing heart, a high temperature, agitation and delirium (severe confusion) ^[36]. If these appear, call your local emergency number (111 in NZ, 000 in Australia, 911 in the US, 999 in the UK) or go to the emergency department.

Drugs Affecting the Liver

NCCIH reports interactions between garcinia cambogia and some drugs affecting the liver ^[2]. If you take any type of medicine, talk with your doctor before using garcinia ^[2].

Theoretical Interactions

NCCIH notes that there are theoretical reasons to suspect garcinia cambogia might interact with other drugs as well ^[2]. If you take prescription medicines, check with your doctor or pharmacist before starting.

Summary of Key Drug Interactions

7. Dietary Sources

Garcinia cambogia is not a nutrient found in typical Western diets. The tree is native to India and Southeast Asia, and the fruit rind has extensive culinary uses ^[2].

Traditional Uses

• Culinary: The fruit is used as a food flavoring agent ^[26].
• Food preservation: The rind has been used historically as a food preservative ^[2].
• Tea: The fruit has been used in folk medicine as a tea for inflammation and stomach complaints ^[2].

Obtaining HCA from Food vs. Supplements

The trials described here used garcinia extracts in caplets, capsules or drinks, not the fruit eaten as food ^{[10, 15, 17]}.

Related Garcinia Species

Other Garcinia species, such as kokum (Garcinia indica) and mangosteen (Garcinia mangostana), are different plants. The trials and case reports in this article concern G. cambogia products.