Una De Gato
Also known as: Cat's claw, Una de Gato, Unha de Gato, Uncaria tomentosa
Overview
Uncaria tomentosa, commonly known as Cat's Claw or Una de Gato, is a woody vine native to the Amazon rainforest, belonging to the Rubiaceae family. Historically, it has been a staple in traditional Peruvian and Brazilian medicine, primarily valued for its anti-inflammatory and immunomodulatory properties. Extracts are typically derived from the stem bark, roots, or leaves, often using aqueous or hydroethanolic solvents. It is widely used as a herbal supplement to address various inflammatory conditions and immune-related disorders. While research on U. tomentosa is ongoing, with several recent systematic reviews and meta-analyses focusing on in vivo (animal) studies, human clinical trials remain limited and less conclusive. The overall quality of evidence is considered moderate, with robust animal studies providing insights into its mechanisms, but a clear need for more extensive and rigorous randomized controlled trials in humans to fully establish its efficacy and safety.
Benefits
Uncaria tomentosa primarily exhibits anti-inflammatory and immunomodulatory effects. Its anti-inflammatory action is attributed to the reduction of key inflammatory mediators such as NF-κB and interleukin-6 (IL-6), with hydroethanolic extracts showing a statistically significant reduction in IL-6 in animal models (SMD: −0.72, 95% CI: −1.15 to −0.29, p=0.001). Immunomodulation involves promoting a Th2 immune profile, which may be beneficial for Th1-mediated disorders, and increasing CD45RA+ B lymphocytes in a dose-dependent manner without systemic toxicity. Secondary benefits include potential cytotoxic effects on various cancer cell lines (e.g., epidermoid carcinoma, breast cancer, sarcoma), demonstrating selective toxicity that spares normal cells, though POA-rich extracts may be an exception. Some in vitro evidence also suggests immune stimulation through enhanced phagocytosis by individual alkaloids. While animal models consistently show these effects, human clinical data are sparse. One small RCT (N=48) indicated that cat's claw gel reduced denture stomatitis severity comparably to miconazole, but without superiority. The effect sizes for IL-6 reduction are moderate and statistically significant in animal studies, but no significant effect on IL-1 or IL-10 levels has been observed.
How it works
Uncaria tomentosa exerts its effects primarily by modulating the immune response. It shifts cytokine profiles towards Th2 dominance and reduces the activity of pro-inflammatory cytokines like IL-6 and NF-κB. This mechanism helps to mitigate inflammation and regulate immune cell function. The vine contains active compounds such as pentacyclic oxindole alkaloids (POAs) and proanthocyanidins (PACs). These compounds are believed to contribute to its biological activities, including promoting apoptosis in certain cancer cells and enhancing the function of immune cells. While its mechanisms are understood at a cellular level, the absorption and bioavailability of its active components in humans are not yet well characterized, though animal studies typically involve oral administration.
Side effects
Uncaria tomentosa generally demonstrates low systemic toxicity in animal studies, even at doses up to 1,250 mg/kg daily for 28 days. However, due to limited human clinical trials, common side effects in humans are not well documented. A potential concern is the rare toxicity observed in vitro from POA-rich extracts to normal cells, suggesting caution with certain preparations. No significant immunotoxicity has been observed in animal models. The current literature does not extensively document significant drug interactions or contraindications for Uncaria tomentosa. However, given its immunomodulatory properties, individuals with autoimmune diseases or those on immunosuppressant medications should exercise caution and consult a healthcare professional before use. Pregnant or breastfeeding women are also advised against its use due to insufficient safety data. While generally considered safe in animal models, the lack of comprehensive human safety data means that potential rare or long-term adverse effects cannot be entirely ruled out.
Dosage
Optimal human dosing for Uncaria tomentosa is not standardized due to limited clinical trials. Animal studies have utilized oral doses ranging from 125 to 1,250 mg/kg daily, typically administered for 28 days. In human research, one clinical trial used a 2% cat's claw gel topically for denture stomatitis, indicating a specific application method rather than systemic oral dosing. The recommended oral dosage for anti-inflammatory or anticancer effects in humans remains undetermined. There are no specific cofactors or absorption enhancers identified that significantly impact its efficacy. Given the lack of standardized human dosing and the potential for varying concentrations of active compounds in different preparations, it is advisable to follow product-specific instructions or consult a healthcare professional for appropriate dosage guidance. Upper limits and safety thresholds for long-term oral use in humans are not well established.
FAQs
Is cat's claw safe?
Animal studies suggest low toxicity. Human safety data are limited, but no major adverse effects have been widely reported. However, POA-rich extracts might pose risks to normal cells in vitro, warranting caution.
Does it reduce inflammation?
Yes, particularly hydroethanolic extracts have been shown to reduce pro-inflammatory markers like IL-6 and NF-κB in animal models, indicating anti-inflammatory properties.
Can it treat cancer?
Preclinical data show selective cytotoxicity against various cancer cell lines, but robust clinical evidence in humans is currently lacking. It is not a proven cancer treatment.
How long does it take to see effects?
Animal studies typically used daily dosing for 28 days to observe effects. Human data are insufficient to provide a clear timeline for when effects might be noticed.
Research Sources
- https://pubmed.ncbi.nlm.nih.gov/38881881/ – This systematic review and meta-analysis of in vivo studies found that hydroethanolic extracts of Uncaria tomentosa significantly reduce IL-6 and NF-κB in animal models, demonstrating anti-inflammatory and immunomodulatory effects with low toxicity. It highlighted the need for more human trials.
- https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2024.1378408/full – This systematic review focused on the preclinical cytotoxicity of Uncaria tomentosa extracts. It found selective cytotoxicity against various cancer cell lines but noted that POA-rich extracts could be toxic to normal cells, emphasizing the need for rigorous clinical trials.
- https://www.drugs.com/npp/cat-s-claw.html – This source provides a general overview of Cat's Claw, including its traditional uses and some research findings. It mentions a small human RCT where cat's claw gel reduced denture stomatitis severity, but without superiority to miconazole.
- https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2025.1584840/full – This source, likely a future publication or pre-print, contributes to the understanding of Uncaria tomentosa's pharmacological properties. It reinforces the findings regarding anti-inflammatory and immunomodulatory effects, particularly in animal models.
- https://pmc.ncbi.nlm.nih.gov/articles/PMC11176511/ – This article, likely a duplicate or related to the PubMed source, discusses the in vivo effects of Uncaria tomentosa. It confirms the reduction of IL-6 and NF-κB and its immunomodulatory properties in animal models, emphasizing its low toxicity.
