Is Horsetail High in Calcium? Understanding Its Surprising Role in Bone Health

November 1, 2025 •

3 min read

With up to 25% of its dry weight composed of silica, the prehistoric plant horsetail is one of the most abundant plant sources of this mineral on Earth. Many people wonder, is horsetail high in calcium, or is another element responsible for its bone-strengthening reputation?

Quick Summary

Horsetail's benefit for bone health is primarily due to its high silica content, which helps the body absorb and utilize calcium effectively, rather than directly supplying large amounts of calcium.

Key Points

Silica-rich, not Calcium-rich: Horsetail contains calcium, but its standout mineral is silica, which is responsible for most of its bone and connective tissue benefits.
Aids Calcium Absorption: The silica in horsetail helps the body to better absorb and use calcium from other dietary sources for bone remineralization.
Supports Collagen Synthesis: Silica is a crucial component for building collagen, the protein framework of bones, cartilage, skin, and nails.
Stimulates Bone-Forming Cells: Horsetail extract has been shown in studies to stimulate osteoblasts (bone-forming cells), which is beneficial for bone strength.
Requires Careful Usage: Due to potential risks like thiamin deficiency and confusion with toxic species, horsetail should be used with caution and under professional guidance.
Combines Best with Other Sources: For a complete approach to bone health, horsetail is most effective when used alongside a diet rich in calcium from foods like dairy, leafy greens, and fortified products.

What's the Real Story: Calcium vs. Silica in Horsetail?

While horsetail does contain calcium, alongside other minerals like potassium and magnesium, it is not primarily considered a top-tier source of dietary calcium. Its powerful effect on bone health is largely attributed to its exceptionally high silica (silicon dioxide) content. This key difference is crucial for understanding how the herb supports the body. Instead of acting as a direct supplier of calcium, horsetail's silica acts as a catalyst, aiding the body in its own calcium metabolism and remineralization processes.

The Critical Role of Silica

Silica is not simply a secondary mineral in horsetail; it is its defining compound. Studies show silica is a crucial element for the formation and repair of connective tissues, cartilage, and bone.

Collagen Synthesis: Silica is essential for synthesizing collagen, a vital protein that provides the framework for your bones, skin, hair, and nails.
Calcium Utilization: It actively helps the body absorb and deposit calcium into bone tissue. This means that consuming horsetail can improve the effectiveness of the calcium you consume from other sources, rather than adding significantly to your calcium intake itself.
Osteoblast Stimulation: Research, including test-tube studies, indicates that horsetail extract can stimulate osteoblasts—the cells responsible for bone formation—while inhibiting osteoclasts, which break down bone tissue. This action is particularly beneficial for conditions like osteoporosis, where bone breakdown outpaces formation.

Horsetail vs. Common Calcium Sources

When comparing horsetail to well-known calcium-rich foods, the distinction in their function becomes clearer. Horsetail is a mineral facilitator with some calcium, while foods like dairy are bulk providers of calcium.


Feature	Horsetail	Dairy/Fortified Foods
Primary Bone Agent	High silica content (catalyst)	High calcium content (raw material)
Main Contribution	Aids calcium absorption and collagen synthesis	Directly provides large quantities of calcium
Best Used For	Supporting healthy bone remodeling and connective tissue	Ensuring adequate dietary calcium intake
Key Benefit	Supports the body's natural remineralization process	Contributes directly to building bone density

Potential Risks and Proper Usage

While horsetail offers notable benefits, it is essential to be aware of the associated risks and proper usage guidelines. The herb is generally recommended for short-term use, typically 2-6 weeks, with breaks in between.

Thiamin Deficiency: Prolonged or excessive use of horsetail can lead to a deficiency in vitamin B1 (thiamin). Heating the herb or buying processed forms can inactivate the responsible enzyme.
Toxic Confusion: It is crucial to distinguish the medicinal field horsetail (Equisetum arvense) from the poisonous marsh horsetail (Equisetum palustre). Never wild-harvest unless you are a trained expert.
Contaminant Accumulation: Horsetail can absorb toxic metals like cadmium and lead from its growing environment. It is important to source products from reputable suppliers to ensure purity.
Medical Supervision: Due to potential interactions with other medications and conditions, particularly kidney issues and lithium, use should be supervised by a healthcare professional.

Diversifying Your Mineral Intake

For optimal bone health, a multifaceted approach is best, combining silica from horsetail with abundant sources of dietary calcium and other cofactors. In addition to dairy, consider incorporating these non-dairy, calcium-rich foods:

Leafy Greens: Bok choy, kale, and collard greens are excellent choices.
Canned Fish: Canned salmon or sardines with the bones included provide significant calcium.
Fortified Foods: Many juices, cereals, and plant-based milks are fortified with calcium.
Legumes: White beans, navy beans, and edamame are good sources.
Nuts and Seeds: Almonds, sesame seeds (tahini), and chia seeds contain notable amounts.

Conclusion

To conclude, is horsetail high in calcium? The answer is no, not in the way dairy products are. Horsetail contains calcium, but its primary benefit for bone health lies in its extraordinarily high concentration of silica. This silica is instrumental in building collagen and enhancing the body's ability to absorb and utilize calcium from other dietary sources. Therefore, instead of viewing horsetail as a direct calcium replacement, it is more accurately seen as a potent herbal synergist that can boost the effectiveness of a calcium-rich diet. By incorporating horsetail correctly, under professional guidance, individuals can support their bone health through improved mineral absorption and collagen synthesis.

For more information on dietary calcium and supplementation, consult the health professional fact sheets from the National Institutes of Health.(https://ods.od.nih.gov/factsheets/Calcium-Consumer/)

Frequently Asked Questions

The primary mineral in horsetail that benefits bones is silica, not calcium. Silica helps facilitate the body's natural bone remineralization processes and is crucial for collagen synthesis.

Horsetail may support increased bone density by providing silica, which enhances collagen synthesis and improves the absorption and use of calcium. Some studies suggest it can stimulate bone-building cells.

The silica in horsetail improves the body's ability to absorb and utilize calcium from other foods. It helps facilitate the deposition of calcium and other minerals into bone and cartilage tissue.

No, horsetail is not a replacement for dairy as a primary calcium source. While it contains some calcium, its main benefit is its high silica content, which acts differently than the bulk calcium found in dairy.

Yes, potential risks include thiamin (vitamin B1) deficiency with long-term use and the possibility of mistaking it for a poisonous marsh horsetail species. It can also accumulate heavy metals from its environment.

Horsetail is typically consumed as a tea, extract, or capsule. It is best used for short periods (e.g., 2-6 weeks) with breaks, and under the guidance of a healthcare professional, especially for those with health conditions or on medication.

While horsetail is exceptionally high in silica, other foods contain it in smaller amounts, including certain algae used in supplements, and minerals present in spring water.