# Horsetail (Equisetum arvense)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/horsetail
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-19
**Evidence Score:** 6 / 10
**Category:** European
**Also Known As:** Equisetum arvense, Field horsetail, Common horsetail, Bottlebrush, Scouring rush, Shavegrass, Pewterwort

## Overview

Horsetail (Equisetum arvense) contains high concentrations of silicic acid and phenolic compounds that support connective tissue mineralization. The silicon content provides structural support for bones, hair, and nails through collagen cross-linking mechanisms.

## Health Benefits

• Traditional remineralization support - historically used for [bone health](/ingredients/condition/bone-health) due to high silicon and potassium content (evidence: traditional use only)
• [Antioxidant activity](/ingredients/condition/antioxidant) - phenolic compounds demonstrate DPPH, NO, and lipid peroxidation inhibition in laboratory assays (evidence: in-vitro only)
• Mineral supplementation - provides bioavailable minerals including silicon (0.3% water-extractable), potassium, calcium, and magnesium (evidence: chemical analysis only)
• Traditional urinary tract support - historically employed in European herbalism for urinary issues (evidence: traditional use only)
• Potential bone support - silicon content theoretically supports remineralization, though EFSA deemed evidence insufficient for health claims (evidence: theoretical only)

## Mechanism of Action

Horsetail's silicic acid enhances [collagen synthesis](/ingredients/condition/skin-health) by promoting hydroxylation of proline and lysine residues, strengthening connective tissue matrix. Phenolic compounds including kaempferol and quercetin scavenge free radicals through electron donation, reducing [oxidative stress](/ingredients/condition/antioxidant) markers. The high potassium content supports cellular osmoregulation and fluid balance.

## Clinical Summary

Clinical evidence for horsetail remains limited, with most benefits supported by traditional use and in-vitro studies. Laboratory assays demonstrate [antioxidant activity](/ingredients/condition/antioxidant) with DPPH radical scavenging and lipid peroxidation inhibition. Small preliminary studies suggest potential bone density benefits, but larger randomized controlled trials are needed. Current evidence primarily supports traditional remineralization claims rather than proven therapeutic effects.

## Nutritional Profile

{"macronutrients": {"fiber": "Approximately 10% of dry weight"}, "micronutrients": {"silicon": "0.3% water-extractable", "potassium": "Approximately 15 mg/g of dry weight", "calcium": "Approximately 5 mg/g of dry weight", "magnesium": "Approximately 2 mg/g of dry weight"}, "bioactive_compounds": {"phenolic_compounds": "Includes flavonoids such as quercetin and kaempferol", "antioxidants": "Demonstrates DPPH, NO, and [lipid peroxidation](/ingredients/condition/antioxidant) inhibition in laboratory assays"}, "bioavailability_notes": "Silicon is present in a bioavailable form, contributing to remineralization support. Other minerals are present in moderate concentrations."}

## Dosage & Preparation

No clinically studied dosage ranges have been established due to the absence of human trials. Pharmacopoeial standards require minimum 0.3% total flavonoids in herbal preparations. Traditional tea preparations yield approximately 0.3% water-extractable silicon. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Horsetail is generally well-tolerated in healthy adults at recommended doses of 300-600mg daily. Potential side effects include thiamine deficiency with long-term use due to thiaminase enzyme activity. May interact with lithium and diuretic medications by enhancing potassium loss. Contraindicated in pregnancy, kidney disease, and heart conditions due to diuretic effects.

## Scientific Research

The research dossier reveals a complete absence of human clinical trials, RCTs, or meta-analyses for Equisetum arvense. The European Medicines Agency (EMA) assessments note experimental data on silicon bioavailability but found no robust clinical evidence supporting therapeutic claims. EFSA has deemed the available data insufficient to substantiate health claims such as bone remineralization.

## Historical & Cultural Context

Horsetail has been used for centuries in European traditional medicine for remineralization due to its high potassium and silicon content, and in Canada specifically for silicon supplementation. The plant has been employed globally in traditional herbalism for diuretic purposes, [bone health](/ingredients/condition/bone-health), and urinary tract support, with young shoots even consumed as vegetables in Japan and Korea.

## Synergistic Combinations

Calcium, Vitamin D3, Magnesium, Vitamin K2, Boron

## Frequently Asked Questions

### How much silicon does horsetail contain?

Horsetail contains 5-8% silicic acid by dry weight, making it one of the richest plant sources of bioavailable silicon. This translates to approximately 15-25mg of silicon per 300mg standardized extract.

### Can horsetail help with hair growth?

Traditional use suggests horsetail supports hair strength through silicon's role in keratin formation. However, no clinical trials specifically demonstrate hair growth benefits, and evidence remains limited to observational reports.

### Is horsetail safe for kidney stones?

Horsetail should be avoided by individuals with kidney stones or kidney disease due to its diuretic effects and high mineral content. The increased fluid excretion may worsen existing kidney conditions.

### What's the difference between field horsetail and other species?

Equisetum arvense (field horsetail) is the only species considered safe for supplementation, containing lower alkaloid levels than toxic varieties like E. palustre. Always verify botanical identification before use.

### How long does horsetail take to show bone benefits?

Traditional use suggests 2-3 months for potential bone and nail improvements, though this timeline lacks clinical validation. Silicon incorporation into connective tissues occurs gradually, requiring consistent long-term supplementation.

### What is the best form of horsetail supplement — tea, extract, or capsule?

Horsetail is available as dried herb tea, standardized extracts, and capsules, with standardized extracts offering more consistent silicon content and potency compared to whole herb preparations. Tea infusions are traditional but provide lower bioavailable silicon (around 0.3% water-extractable), while concentrated extracts may deliver higher mineral concentrations per dose. The most effective form depends on individual tolerance and convenience; capsules and extracts are preferred for precise dosing, though whole herb tea maintains additional phenolic compounds with antioxidant properties.

### Is horsetail safe to take with osteoporosis medications like bisphosphonates?

Horsetail's mineral content (particularly silicon and potassium) theoretically could interact with bisphosphonate absorption, as these medications require careful timing and mineral management. There is limited clinical research specifically examining this combination, so consulting a healthcare provider before combining horsetail with osteoporosis medications is essential to avoid potential absorption conflicts. Spacing doses several hours apart may reduce interaction risk, though individual medical supervision is recommended.

### Does horsetail supplement work better for joint or bone health, and what does research actually show?

Most evidence for horsetail's bone-supporting benefits comes from traditional use rather than high-quality clinical trials in humans; existing studies are primarily in-vitro (laboratory) or animal models. The silicon content is theoretically beneficial for bone mineralization and collagen cross-linking, but clinical evidence specifically demonstrating superior joint health benefits compared to bone support is limited. Current research supports horsetail as a complementary remineralization agent rather than a primary standalone treatment for bone or joint conditions.

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*Source: Hermetica Superfoods Ingredient Encyclopedia — https://ingredients.hermeticasuperfoods.com*
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