Wise Mind Herbs

The information on this page has been prepared with reference to published scientific literature, not by a medically qualified expert. It is not medical advice. Any decision to use a supplement or herb-based product is your responsibility. Consult a suitably qualified medical professional, especially if you have underlying conditions. Remember, nothing is for everyone, and not everything sold is what it claims to be. Some things work for some people, some of the time.

Horsetail - Equisetum arvense

Horsetail (Equisetum) is one of the oldest plant families on Earth, dating back to prehistoric times. The most commonly used species in herbal medicine is Equisetum arvense (field horsetail), though other species including E. hyemale (rough horsetail), E. telmateia (great horsetail), and E. fluviatile (water horsetail) are also utilized. These plants are sometimes confused with other species such as Ephedra (Mormon tea or ma huang), which belongs to a different plant family and has distinct chemical properties.

Bioactive Compounds

Horsetail contains several bioactive compounds, with silica (silicon dioxide) being the most abundant and therapeutically significant, constituting up to 10% of the dry weight. Other notable compounds include flavonoids (quercetin, isoquercitrin, kaempferol), phenolic acids (caffeic acid, ferulic acid), triterpenoids, phytosterols, alkaloids (nicotine, palustrine), minerals (potassium, calcium, manganese), and saponins. These compounds contribute to horsetail's various medicinal properties.

Evidence-Based Health Benefits

Modern scientific research has investigated horsetail's traditional uses, with varying levels of evidence supporting its efficacy for different conditions:

• Bone and Connective Tissue Health: Multiple studies suggest that horsetail's high silica content may support bone mineralization and collagen synthesis.Horsetail extract supplementation (10 mg/day of silica) for 12 weeks might improve bone mineral density markers in postmenopausal women with osteopenia.
• Diuretic Effects: Clinical evidence supports horsetail's traditional use as a diuretic. Standardized horsetail extract (900 mg/day) has been shown to have diuretic efficacy comparable to hydrochlorothiazide (25 mg/day) but with milder electrolyte disturbances.
• Wound Healing: In vitro and animal studies suggest that horsetail extracts promote wound healing by stimulating fibroblast proliferation and enhancing collagen production. Topical 2% horsetail extract cream has been demonstrated to accelerate healing of minor burns compared to standard care.
• Antioxidant Effects: Laboratory studies confirm horsetail's significant antioxidant capacity, attributable to its flavonoid and phenolic acid content. However, the clinical relevance of these effects remains under investigation.
• Anti-inflammatory Activity: Several in vitro and animal studies have demonstrated horsetail's anti-inflammatory properties, particularly in models of respiratory and urinary tract inflammation.
• Kidney and Urinary Tract Health: Some clinical evidence supports horsetail's use for urinary tract infections and kidney stones, primarily due to its diuretic and mild antimicrobial properties.

Conditions with Limited Evidence

The following conditions have been associated with horsetail use in traditional medicine, but currently lack robust clinical evidence:

• Nail and Hair Strength: Although silica is important for keratin production, clinical trials specifically examining horsetail's effects on hair and nail health are limited.
• Blood Glucose Regulation: Some preclinical studies suggest potential hypoglycemic effects, but human trials are insufficient.
• Cognitive Function: Limited animal studies suggest neuroprotective properties, but human research is lacking.
• Antimicrobial Activity: In vitro studies show activity against certain bacteria and fungi, but clinical applications require further investigation.

Recommended Dosages

Based on clinical studies and traditional use, the following dosages are typically recommended for adults:

• Dried Herb: 2-3 g taken 3 times daily (standardized to contain 10-15% silica)
• Fluid Extract (1:1): 1-4 mL, 3 times daily
• Tincture (1:5): 2-6 mL, 3 times daily
• Standardized Extract: 300-600 mg daily (standardized to 10-15% silica or 0.1% total flavonoids)
• For Topical Use: Creams or ointments containing 2-5% horsetail extract

It's important to note that most clinical studies have used standardized extracts rather than raw herb preparations, which may have variable active constituent content.

Side Effects and Safety Concerns

Horsetail is generally considered safe when used appropriately, but several concerns warrant attention:

• Thiamine Depletion: Horsetail contains thiaminase, an enzyme that breaks down vitamin B1 (thiamine). Long-term use may lead to thiamine deficiency. Properly dried or processed commercial preparations typically have reduced thiaminase activity.
• Electrolyte Imbalance: Due to its diuretic effect, prolonged use may cause potassium depletion and electrolyte imbalances.
• Nicotine Content: Some Equisetum species contain trace amounts of nicotine, which may be problematic for sensitive individuals.
• Heavy Metal Accumulation: Horsetail can bioaccumulate heavy metals from soil, particularly nickel and cadmium, making quality sourcing important.
• Drug Interactions: May potentiate the effects of diuretic medications, lithium, digoxin, and medications that lower potassium levels.
• Pregnancy and Lactation: Not recommended due to insufficient safety data and potential nicotine content.

High-Dose Studies and Knowledge Gaps

Studies investigating doses significantly above the recommended therapeutic range are limited. The effects of high-dose horsetail extract (equivalent to 5-10 times the recommended human dose) has been studied in rats over 90 days. No major organ toxicity was observed, but significant diuresis and mild electrolyte disturbances occurred. The most common adverse effects reported in human studies using high doses (>1000 mg/day of standardized extract) included headache, gastrointestinal discomfort, and mild electrolyte imbalances.

Significant knowledge gaps exist regarding:

• Long-term safety (studies beyond 6 months are scarce)
• Potential benefits of ultra-high silica extraction methods
• Comparative efficacy of different Equisetum species
• Pharmacokinetics and bioavailability of key compounds
• Optimal standardization parameters for different therapeutic applications
• Effects in pediatric, geriatric, and immunocompromised populations

Commercial Pharmaceutical Products

While horsetail is primarily available as herbal supplements, teas, and topical preparations, a few pharmaceutical products incorporate horsetail extracts:

• EquiSil®: Standardized horsetail extract tablets for urinary tract conditions and mild edema.
• Osteosil®: Combined silica and calcium preparation for bone health.
• Bio-Silica-MSM®: Horsetail-derived bioavailable silica for connective tissue support.

Note that many of these products may have limited availability outside their countries of origin, and regulatory status varies by region.

Conclusion

Horsetail has demonstrated promising potential for conditions related to bone health, urinary tract function, and wound healing. However, the quality of evidence varies considerably across different applications. Standardization of extracts, appropriate dosing, and awareness of potential side effects are essential for safe and effective use. Further rigorous clinical trials, particularly long-term studies and meta-analyses, are needed to better establish efficacy and safety profiles.

References

Al-Snafi, A. E. (2017). The pharmacology of Equisetum arvense-A review. IOSR Journal of Pharmacy, 7(2), 31-42.

Čanadanović-Brunet, J. M., Ćetković, G. S., Djilas, S. M., Tumbas, V. T., Savatović, S. S., Mandić, A. I., ... & Cvetković, D. D. (2009). Radical scavenging and antimicrobial activity of horsetail (Equisetum arvense L.) extracts. International Journal of Food Science and Technology, 44(2), 269-278.

Carneiro, D. M., Freire, R. C., Honório, T. C. D. D., Zoghaib, I., Cardoso, F. F. D. S. E. S., Tresvenzol, L. M. F., ... & Cunha, L. C. D. (2014). Randomized, Double‐Blind Clinical Trial to Assess the Acute Diuretic Effect of Equisetum arvense (Field Horsetail) in Healthy Volunteers. Evidence‐Based Complementary and Alternative Medicine, 2014(1), 760683.

Carneiro, D. M., Jardim, T. V., Araújo, Y. C. L., Arantes, A. C., de Sousa, A. C., Barroso, W. K. S., ... & Jardim, P. C. B. V. (2022). Antihypertensive effect of Equisetum arvense L.: a double-blind, randomized efficacy and safety clinical trial. Phytomedicine, 99, 153955.

Eren, A., İnci, Ş., & Kırbağ, S. (2024). The Antimicrobial and Antioxidant Effects of Equisetum arvense Extracts. Turkish Journal of Science and Technology, 19(2), 373-378.

Farooq, M. A., & Dietz, K. J. (2015). Silicon as versatile player in plant and human biology: overlooked and poorly understood. Frontiers in plant science, 6, 994.

Kim, M. H., Bae, Y. J., Choi, M. K., & Chung, Y. S. (2009). Silicon supplementation improves the bone mineral density of calcium-deficient ovariectomized rats by reducing bone resorption. Biological trace element research, 128, 239-247.

Luanda, A., Ripanda, A., & Makangara, J. J. (2023). Therapeutic potential of Equisetum arvense L. for management of medical conditions. Phytomedicine Plus, 3(2), 100444.