Silica (Bioavailable Silicon)
A trace mineral important for collagen cross-linking, bone matrix formation, and connective tissue integrity, commonly used for hair, skin, and nail support.
What is Silica (Bioavailable Silicon)?
Silica (silicon dioxide, SiO₂) is the most common form of silicon in nature. In nutrition, bioavailable silicon — primarily as orthosilicic acid (OSA, Si(OH)₄) — is the form absorbed and utilized by the body. Silicon is the third most abundant trace element in the human body and is concentrated in connective tissues, bone, skin, hair, and nails.
Known Health Benefits
How It Works
Silicon stimulates prolyl hydroxylase, an enzyme critical for collagen synthesis and cross-linking. It also plays a structural role in glycosaminoglycans (GAGs) and proteoglycans that form the extracellular matrix of connective tissues. In bone, silicon is found at active mineralization sites and appears to promote osteoblast differentiation and inhibit osteoclast activity. Silicon also stabilizes the collagen-hydroxyapatite interface in bone matrix. The exact biochemical mechanisms are still being elucidated — silicon is one of the least understood essential trace elements.
What Research Says
The Framingham Offspring Cohort study (2004, Journal of Bone and Mineral Research) found that higher dietary silicon intake was significantly associated with greater bone mineral density at the hip in men and premenopausal women. A 2005 double-blind RCT in the Archives of Dermatological Research showed choline-stabilized orthosilicic acid (ch-OSA) improved hair tensile strength, thickness, and skin elasticity after 20 weeks. A 2008 study demonstrated that ch-OSA supplementation alongside calcium and vitamin D3 increased femoral BMD more than calcium and D3 alone in osteopenic women.
Active Compounds
Orthosilicic acid (OSA), bioavailable silicon
Forms & Bioavailability
Orthosilicic acid (OSA) is the only form of silicon readily absorbed by the GI tract, with approximately 50% bioavailability. Most dietary and supplemental silica must be converted to OSA in the acidic environment of the stomach. Choline-stabilized OSA (ch-OSA) prevents polymerization and maintains silicon in the absorbable monomeric form. Colloidal silica and horsetail extract have very low bioavailability (<1–5%).
Dosage Guidance
| Use Case | Dosage |
|---|---|
| Hair, skin, and nail support | 5–10 mg bioavailable Si (ch-OSA) |
| Bone health (adjunct) | 6–12 mg bioavailable Si |
| Collagen support / anti-aging | 5–10 mg bioavailable Si |
| General connective tissue | 10–30 mg bioavailable Si |
Always consult a healthcare provider for personalized dosing.
Natural Food Sources
- Beer (6–56 mg per liter — from barley and hops)
- Oats (6 mg per serving)
- Brown rice (4.5 mg per serving)
- Bananas (4.8 mg per medium)
- Green beans (3 mg per cup)
- Mineral water (varies by source; 5–50 mg/L)
- Horsetail herb (traditional source; variable and poorly absorbed)
Potential Side Effects
Generally very safe in food-grade and supplement forms
Who Should Avoid It
- Chronic kidney disease — silicon excretion is renal; theoretical accumulation risk (silica urolithiasis is very rare)
- No well-established contraindications at dietary and standard supplement doses
Pregnancy & Lactation
Silicon is present in standard diets at 20–50 mg/day and is not known to be toxic at these levels. No specific studies on ch-OSA supplementation during pregnancy or lactation exist. Given limited data, supplementation during pregnancy should be deferred unless nutritionally necessary. Dietary silicon intake is considered safe.
Known Drug Interactions
May reduce absorption of some minerals if taken simultaneously
Evidence Classification
Based on in vitro studies, animal models, pilot trials, or traditional use documentation. Clinical evidence is limited.
Frequently Asked Questions
Does silica really help with hair growth?
A double-blind RCT using choline-stabilized orthosilicic acid (ch-OSA) showed statistically significant improvements in hair tensile strength and thickness after 20 weeks. Silicon supports keratin and collagen, both structural proteins in hair.
What is the best form of silica to take?
Choline-stabilized orthosilicic acid (ch-OSA, marketed as BioSil) is the most bioavailable form, with approximately 50% absorption. Horsetail extract and colloidal silica are poorly absorbed and not recommended for therapeutic use.
Can silica help with bone health?
Yes. The Framingham study linked higher silicon intake to greater bone density. Silicon is found at active bone mineralization sites and promotes osteoblast activity. A clinical trial showed ch-OSA + calcium + D3 improved bone density more than calcium + D3 alone.
How is silica different from collagen supplements?
They are complementary. Silica activates the enzymes that cross-link and stabilize collagen fibers, while collagen supplements provide the raw amino acid building blocks. Taking both together may offer synergistic benefits.
Is the silica in horsetail effective?
Horsetail (Equisetum arvense) is a traditional silica source, but the silicon is primarily in insoluble crystalline form with very low bioavailability (< 5%). Unless the extract is processed to release orthosilicic acid, horsetail supplements provide little usable silicon.
How long does it take to see results from silica supplementation?
Hair and nail improvements typically require 12–20 weeks of consistent supplementation. Skin elasticity improvements may be noticed sooner (8–12 weeks). Bone density changes take 12+ months to measure.
References
- Dietary silicon intake is positively associated with bone mineral density in men and premenopausal women of the Framingham Offspring cohort. Jugdaohsingh R, Tucker KL, Qiao N, et al.. Journal of Bone and Mineral Research (2004)View study
- Effect of oral intake of choline-stabilized orthosilicic acid on skin, nails and hair in women with photodamaged skin. Barel A, Calomme M, Timchenko A, et al.. Archives of Dermatological Research (2005)View study
- Silicon supplementation with choline-stabilized orthosilicic acid (ch-OSA) added to calcium/vitamin D3 increases markers of bone formation and bone mineral density in osteopenic women. Spector TD, Calomme MR, Anderson SH, et al.. BMC Musculoskeletal Disorders (2008)View study
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This entry is for educational purposes only. It is not medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement regimen, especially if you take medications or have health conditions.