What is hydroxycitric acid (HCA)?
Hydroxycitric acid, or HCA, is a chemical compound found predominantly in the rinds of the Garcinia fruit, most notably Garcinia cambogia. For centuries, this fruit has been used for culinary purposes in Southeast Asia. HCA is the active component believed to have anti-obesity effects by inhibiting an enzyme called ATP-citrate lyase, which is involved in fat synthesis. It is also thought to increase serotonin levels, which can help suppress appetite. HCA is a popular ingredient in weight-loss supplements, often sold in pill or powder form.
Short-term safety: A qualified “Possibly Safe”
For most people, taking hydroxycitric acid orally for periods of 12 weeks or less is considered possibly safe. Clinical studies examining short-term use in humans have generally reported mild side effects, such as nausea, headaches, and digestive tract discomfort, with no significant adverse effects. For example, one review of 14 double-blind trials on HCA found no significant adverse effects, though the studies were all short-term (less than 12 weeks). A controlled study in healthy men found no toxicological changes with a dose of 3,000 mg/day for 30 days.
Long-term safety: Evidence is lacking
Crucially, the long-term safety of hydroxycitric acid is unknown. The majority of human studies on HCA have been small and short in duration, typically not extending beyond 12 weeks. This means there is insufficient evidence to determine the effects of sustained HCA consumption over longer periods, and further long-term clinical trials are needed.
Risks and side effects of HCA
Despite generally positive short-term safety profiles in many controlled studies, there have been several significant safety concerns and reported side effects associated with HCA, especially when taken as part of multi-ingredient supplements.
- Hepatotoxicity (liver damage): In rare cases, the use of supplements containing Garcinia cambogia and HCA has been linked to severe liver injury, including hepatitis and liver failure requiring transplantation. Regulatory bodies, such as the Therapeutic Goods Administration (TGA) in Australia and Health Canada, have issued safety warnings about this risk. Some reports suggest that liver issues may be idiosyncratic, meaning they are not dose- or duration-dependent. The supplement Hydroxycut was also linked to liver toxicity, though it contained multiple ingredients, making it difficult to isolate HCA as the sole cause.
- Drug interactions: HCA may interact with certain medications, posing a risk of dangerous side effects.
- Diabetes medications: HCA can lower blood sugar, potentially causing it to drop too low in people taking anti-diabetes drugs like glimepiride or insulin.
- Blood-thinning medications: There is a concern that HCA might slow blood clotting. Taking it with anticoagulant or antiplatelet drugs could increase the risk of bleeding and bruising.
- Serotonergic drugs: HCA may increase serotonin levels. Combining it with SSRI antidepressants or other serotonergic drugs could lead to a dangerous excess of serotonin, causing severe side effects like seizures and heart problems.
- Other side effects: Common, milder side effects reported include headaches, nausea, digestive upset, dry mouth, and diarrhea. In some cases, more severe reactions like mania, psychosis, or cardiomyopathy have been reported with HCA-containing products.
- Uncertainty in supplement quality: The actual HCA content and the presence of other unlisted or harmful ingredients can vary greatly across different supplements, increasing the risk of adverse effects. This makes it difficult to assess the risk of a specific product.
Who should avoid HCA?
Given the risks, certain individuals should completely avoid or exercise extreme caution with HCA supplements:
- Pregnant or breastfeeding women: Lack of safety data means HCA use should be avoided.
- Individuals with liver disease or damage: Due to the reported risk of hepatotoxicity, those with existing liver issues should not take HCA.
- People with diabetes: HCA's effect on blood sugar necessitates careful monitoring and medical supervision for diabetics.
- Individuals with bleeding disorders: The potential for slowed blood clotting makes HCA risky.
- People on certain medications: Those taking antidepressants or blood-thinners must avoid HCA due to interaction risks.
HCA and Garcinia Cambogia vs. Placebo: A Comparison
| Feature | HCA / Garcinia Cambogia | Placebo (no HCA) | Finding Source |
|---|---|---|---|
| Weight Loss | Mixed results; some studies show modest short-term effects, while larger, more rigorous trials show no significant difference from placebo. | Modest weight loss often occurs due to diet and lifestyle changes in controlled studies. | JAMA, ScienceDirect |
| Fat Mass Reduction | Inconsistent findings; some claim fat reduction, but significant body fat mass reduction beyond placebo effects is not well-supported. | Any fat mass reduction is attributed to diet and other interventions. | JAMA |
| Appetite Suppression | Animal studies suggest an effect via increased serotonin, but human trials have had mixed outcomes. | No effect on appetite directly, but can be influenced by psychological factors and diet changes. | WebMD, NIH |
| Side Effects (Short-Term) | Possibility of mild side effects like nausea, headache, and digestive upset. | Generally low incidence, consistent with population baseline. | RxList, NIH |
Conclusion
While marketed extensively as a weight-loss supplement, definitive evidence that hydroxycitric acid is safe and effective long-term is lacking. Short-term use (under 12 weeks) is considered possibly safe for most healthy individuals, but the long-term safety profile is unknown. The rare but serious risk of liver toxicity, potentially exacerbated by other ingredients in multi-component supplements, is a significant concern that has prompted regulatory warnings. Furthermore, HCA carries a risk of moderate to severe drug interactions, particularly for those on medication for diabetes, bleeding disorders, or depression. Always consult a healthcare provider before using HCA or any supplement, especially if you have pre-existing health conditions or are taking other medications.
Further reading
- Hydroxycitric Acid (HCA) safety review by Health Canada
- Hydroxycitric acid does not promote inflammation or liver toxicity (an older review)
- WebMD overview on Garcinia (HCA) with side effects and interactions
In summary, the question "is hydroxycitric acid safe?" does not have a simple "yes" or "no" answer. It depends on several factors, including the dosage, duration of use, individual health status, and other ingredients in the supplement. The prudent approach is to exercise caution and prioritize professional medical advice.
Key takeaways
- Short-term is possibly safe: Hydroxycitric acid (HCA) appears possibly safe for most people when taken for 12 weeks or less, though mild side effects can occur.
- Long-term safety is unknown: There is insufficient evidence from clinical trials to confirm the safety of long-term HCA supplementation.
- Risk of liver injury: Rare but serious cases of liver damage, including liver failure, have been linked to HCA-containing supplements, leading to regulatory warnings.
- Significant drug interactions: HCA can interact negatively with medications for diabetes, blood clotting, and depression, potentially causing severe health issues.
- Supplement quality is inconsistent: The actual content and purity of HCA in over-the-counter supplements can vary, posing an additional risk.
FAQs
Question: How long can I safely take hydroxycitric acid? Answer: HCA is considered possibly safe for short-term use of 12 weeks or less, but its safety for longer periods has not been established through sufficient research.
Question: What are the most common side effects of HCA? Answer: The most common mild side effects reported include headaches, nausea, and digestive upset like stomach discomfort and diarrhea.
Question: Can HCA cause liver damage? Answer: In rare instances, supplements containing HCA have been associated with severe liver injury, including hepatitis and liver failure. Health authorities have issued warnings about this risk.
Question: Who should not take HCA? Answer: Individuals who are pregnant or breastfeeding, have pre-existing liver disease, diabetes, bleeding disorders, or are taking antidepressants should not use HCA.
Question: Does HCA really help with weight loss? Answer: The evidence for HCA's effectiveness in promoting weight loss is mixed and contradictory. While some studies show modest short-term results, many larger, controlled trials have shown no significant effect compared to a placebo.
Question: How does HCA interact with medications? Answer: HCA can interact moderately with blood-thinning medications, anti-diabetes drugs, and serotonergic drugs (like some antidepressants), affecting their efficacy or increasing the risk of serious side effects.
Question: Why are there conflicting reports on HCA safety and efficacy? Answer: Conflicting reports often arise due to variations in study design, small sample sizes, the presence of other ingredients in multi-component supplements, and issues with the quality and dosage of supplements used.
