Garcinia Cambogia (HCA) | Supplementopedia

Overview

Garcinia cambogia is a tropical fruit native to Southeast Asia. Its rind contains a high concentration of hydroxy‑citric acid (HCA), a naturally occurring organic acid. In dietary‑supplement form, HCA is marketed primarily as a weight‑management aid because it can influence carbohydrate metabolism and appetite regulation.

Benefits

Weight and Adiposity: Clinical trials and meta‑analyses have identified modest, reproducible benefits of HCA supplementation on body weight and adiposity when combined with a calorie‑restricted diet, with average reductions of 1–2 kg over 8–12 weeks in some studies.
Lipid Profile Improvement: HCA also modestly improves lipid profiles (↓ triglycerides, ↑ HDL) and fasting glucose in overweight adults.
Neuroprotective Activity: In animal models, HCA shows neuroprotective activity through oxidative‑stress reduction, but human cognitive data remain limited.
Satiety Hormones and Energy Expenditure: Some evidence suggests a small increase in satiety hormones (e.g., leptin) and a modest rise in resting energy expenditure.
Muscle Strength and Aerobic Performance: Effects on muscle strength or aerobic performance are negligible.
Reliable Evidence: The most reliable evidence supports modest metabolic benefits (weight, lipids) and a possible appetite‑suppressing effect; other claimed benefits (e.g., “detox” or “muscle building”) lack robust data.

How It Works

ATP-Citrate Lyase Inhibition: HCA primarily inhibits ATP‑citrate lyase, the cytosolic enzyme that cleaves citrate to acetyl‑CoA and oxaloacetate—key precursors for de novo lipogenesis.
Fatty Acid Reduction: By blocking this step, HCA reduces the conversion of excess carbohydrates into fatty acids, thereby limiting triglyceride synthesis.
Serotonin Enhancement: HCA also raises brain serotonin by increasing tryptophan uptake and reducing serotonin degradation, which may enhance satiety signals.
β-Oxidation Stimulation: Additionally, HCA can modestly stimulate β‑oxidation via activation of AMP‑activated protein kinase (AMPK) in peripheral tissues, increasing fatty‑acid oxidation.
Net Effect: Together, these pathways lower caloric storage, modestly raise energy expenditure, and enhance central appetite control. The net effect is a modest reduction in net energy balance when combined with dietary restriction.

Dosage

Typical Dosage in Research: Research studies most commonly use 500 mg of HCA per capsule, taken 30 minutes before meals, 2–3 times daily, yielding a total daily dose of 1,500 mg to 2,500 mg of pure HCA.
Effective Dosage: A “standard” dose of 1 g/day (split into two doses) has been shown to be effective in weight‑loss trials.
Higher Dosage Studies: Higher doses (up to 3 g/day) have been studied without significant additional benefit.
Appetite Control Dosage: For appetite‑control purposes, 500 mg before each main meal (≈1.5 g/day) is typical.
Precautions: Users with liver disease, pregnant or lactating women, and individuals on serotonergic medications should start at the lower end (≈500 mg/day) and consult a health professional.
Consistency and Diet: Consistency (daily dosing) and pairing with a hypocaloric diet improve outcomes.

Safety & Side Effects

General Tolerance: Garcinia cambogia is generally well tolerated at ≤3 g/day.
Adverse Events: Mild adverse events—headache, gastrointestinal upset, and mild liver enzyme elevations—have been reported.
Hepatotoxicity: Rare cases of hepatotoxicity have been described, often in products with poor quality control or high‑dose regimens; routine liver‑function monitoring is advisable for prolonged use (>12 weeks).
Contraindications: Contraindications include pregnancy, lactation, and known hepatic disease.
Drug Interactions: HCA may potentiate serotonergic drugs (SSRIs, MAO‑I, tramadol) and increase risk of serotonin syndrome; caution is advised.
Additive Effects: People on antidiabetic agents may experience additive glucose‑lowering effects, requiring dose adjustment.
Consultation Advised: Children, individuals with kidney disease, and those on anticoagulants should consult a clinician before use.

Chemistry

Molecular Formula and Weight: Hydroxy‑citric acid (HCA) is a tricarboxylic acid with the molecular formula C₆H₈O₈ and a molecular weight of 192.12 g·mol⁻¹.
IUPAC Name: The IUPAC name is 2‑hydroxy‑1,2,3‑propane‑tricarboxylic acid.
Structure: Its structure features a central carbon bearing a hydroxyl group (‑OH) and three carboxylate groups (‑COOH) attached to a three‑carbon backbone.
Stereoisomer: The compound is a stereoisomer—most commercial extracts contain the (−)-HCA enantiomer, which is biologically active.
Solubility and Stability: HCA is water‑soluble, stable at pH 3–5, and degrades under alkaline conditions.
Lipophilicity and Absorption: The molecule’s high polarity results in low lipophilicity (log P ≈ −0.5), limiting passive cellular uptake; absorption is mediated by active transport in the small intestine.

Sources & Quality

Source: Commercial HCA is extracted from the rind of Garcinia cambogia fruit (family Clusiaceae).
Harvesting Regions: The fruit is harvested in tropical regions (India, Indonesia, Thailand, Philippines).
Extraction Process: The dried rind is pulverized and subjected to aqueous or ethanol extraction, followed by filtration, concentration, and spray‑drying to obtain a powdered HCA.
HCA Content: Powdered HCA contains ≥ 50 % HCA, often 60–70 % in standardized extracts.
Standardization: Some manufacturers use a “standardized 60 % HCA” label to indicate potency.
Quality Considerations: Quality considerations include verification of the (−)-HCA enantiomer, absence of heavy metals, pesticide residues, and mycotoxins.
Supplement Reliability: Good Manufacturing Practice (GMP) certification, third‑party testing (e.g., USP, NSF), and a clear certificate of analysis are essential for reliable, safe supplements.