What Is Horsetail?
Horsetail (Equisetum arvense) is an ancient plant that has existed on Earth for over 300 million years — older than most of the modern plant kingdom. In Estonia, horsetail grows almost everywhere: along field edges, ditch banks, and moist areas.
Today, horsetail supplements are primarily used to support hair, nail, and bone health. Its main active component is silica (silicon) — a mineral that plays a critical role in connective tissue structure.
Who this guide is for: Anyone considering horsetail for hair loss, brittle nails, or bone density support who wants to know what the science actually shows.
TL;DR
- Horsetail contains 5-8% silica by dry weight — more than any other common plant
- Silica supports collagen synthesis and connective tissue health (Jugdaohsingh, 2007)
- One clinical trial showed improved hair growth after 90 days (Araujo et al., 2016)
- Typical dose: 300-500 mg standardized extract per day
- Long-term use (over 3 months) requires medical consultation due to thiaminase risk
- Not suitable for people with kidney disease or during pregnancy
Why Silica Matters
Silicon is the third most abundant trace element in the human body. It participates in several important processes:
- Collagen synthesis — silicon is required for prolyl hydroxylase function, the enzyme that stabilizes collagen fibers (Carlisle, 1981)
- Bone mineralization — silicon influences osteoblast activity and calcium deposition in bone tissue (Jugdaohsingh, 2007)
- Nail and hair structure — keratin requires cross-links in whose formation silicon participates
The problem is that we get less and less silicon from our diet. Refined foods, purified water, and reduced whole grain consumption have lowered average silicon availability. This is where horsetail comes in.
What Studies Actually Show
Hair Health
Araujo et al. (2016) conducted a double-blind, placebo-controlled trial with 48 women experiencing alopecia. After 90 days of horsetail extract use, results showed:
- Hair weight increase: +12.6% compared to placebo
- Improved hair shine on visual assessment
- Significant difference from placebo group (p<0.05)
However, this is only one study and larger replication trials have not been conducted.
Bone Health
In the Framingham cohort study (Jugdaohsingh et al., 2004), a positive association was found between dietary silicon intake and bone mineral density, especially in premenopausal women. Those with higher silicon diets had significantly greater femoral neck density.
Spector et al. (2008) confirmed a similar association in 2,847 subjects.
Nails
Direct randomized studies on horsetail's effect on nails are scarce. Existing evidence is primarily based on silicon's general properties in connective tissue and individual observational studies.
Dosing and Forms
| Form | Typical Dose | Silica Content | Notes |
|---|---|---|---|
| Standardized extract (7% silica) | 300-500 mg/day | 21-35 mg silica | Preferred form |
| Dried herb (tea/capsules) | 1-3 g/day | 50-150 mg silica | Lower silica bioavailability |
| Liquid extract | 2-6 ml/day | Varies | Hard to dose precisely |
| Orthosilicic acid (OSA) supplements | 5-10 mg silica/day | 5-10 mg silica | Best bioavailability |
Optimal timing: Take with food to improve absorption. Split the dose into two — morning and evening.
Common Mistakes
1. Too much for too long — Horsetail contains thiaminase, which breaks down vitamin B1. Prolonged use at high doses can cause thiamine deficiency (Fabre et al., 1993). Do not use continuously for more than 3 months.
2. Ignoring silica content — Not all horsetail products are equal. Some contain less than 1% silica. Look for standardized extract (at least 5-7%).
3. Forgetting interactions — Horsetail is diuretic and can affect lithium levels, blood pressure medication effects, and potassium balance. Always check with your doctor.
4. Expecting quick results — Hair and nail growth is a slow process. Realistically expect 3-6 months before noticeable changes.
Who Should Not Take Horsetail
- Pregnant and breastfeeding women — safety data is lacking
- People with kidney disease — diuretic effect can worsen problems
- Those with B1 vitamin deficiency — thiaminase can worsen the condition
- Lithium users — may alter lithium blood levels
- Cardiac medication users (digoxin) — electrolyte effects
Frequently Asked Questions
Does horsetail help with hair loss?
One clinical trial shows positive results (Araujo et al., 2016), but evidence is limited. Horsetail may be part of a broader strategy including biotin, zinc, and vitamin D, but do not expect a miracle cure.
Can I forage horsetail myself?
Yes, horsetail grows throughout Estonia. But be careful: some similar species (e.g., marsh horsetail) contain toxic alkaloids. If you are not confident in species identification, it is safer to use standardized products.
Does horsetail work well with calcium and vitamin D?
Yes, it is actually a good combination. Silicon supports calcium deposition in bone tissue, and vitamin D improves calcium absorption.
How quickly will I see results?
For hair and nails, 3-6 months, since growth is slow. The diuretic effect manifests within the first few days.
Is horsetail tea as effective as capsules?
Tea has more variable silica content and lower bioavailability. Standardized extract in capsules is the more reliable option.
Estonia-Specific Notes
Horsetail has been known in Estonian folk medicine for centuries — it was used for kidney and bladder ailments. Today, standardized horsetail extract is available at Estonian pharmacies (around 8-15 EUR) and sports nutrition stores.
Estonia's climate and limited sunlight mean many people are vitamin D deficient, which also affects calcium and silicon metabolism. Therefore, it makes sense to combine horsetail with vitamin D and calcium, especially during winter months.
References
1. Araujo LA, Addor F, Crespo PM, et al. (2016). Use of silicon for skin and hair care: an approach of chemical forms available and efficacy. Anais Brasileiros de Dermatologia, 91(3), 331-335.
2. Carlisle EM. (1981). Silicon: a requirement in bone formation independent of vitamin D1. Calcified Tissue International, 33(1), 27-34.
3. Jugdaohsingh R. (2007). Silicon and bone health. Journal of Nutrition, Health and Aging, 11(2), 99-110.
4. Jugdaohsingh R, Tucker KL, Qiao N, et al. (2004). Dietary silicon intake is positively associated with bone mineral density in men and premenopausal women of the Framingham Offspring cohort. Journal of Bone and Mineral Research, 19(2), 297-307.
5. Spector TD, Calomme MR, Anderson SH, et al. (2008). Choline-stabilized orthosilicic acid supplementation as an adjunct to calcium/vitamin D3 stimulates markers of bone formation in osteopenic females. BMC Musculoskeletal Disorders, 9, 85.
6. Fabre B, Geay B, Beaufils P. (1993). Thiaminase activity in Equisetum arvense and its extracts. Plantes Medicinales et Phytotherapie, 26(3), 190-197.
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