Research dossier
Clinical research on Silica
4 trials reviewed across 4 indications.
Strongest evidence
Bone density
Mechanism
Silicon participates in collagen cross-linking and the formation of glycosaminoglycans in the bone matrix. Orthosilicic acid is the bioavailable circulating form. The mechanistic story is plausible; the controlled-trial story is small.
The Framingham cohort linked higher silicon intake to higher hip bone mineral density, and one 12-month trial (Spector 2008) showed modest improvements in bone formation markers and femoral density when ChOS was added on top of calcium and vitamin D. The effect is real but small, and there are no fracture-endpoint trials.
Helpful adjunct for postmenopausal bone health, layered on top of standard care (calcium, vitamin D, K2, weight-bearing activity). Not a standalone osteoporosis treatment.
Trials cited
Dietary silicon and bone mineral density (Framingham)
positive · Observational
Jugdaohsingh et al., 2004, Journal of Bone and Mineral Researchn=2847Higher dietary silicon intake was associated with higher hip bone mineral density in men and premenopausal women in the Framingham Offspring cohort. The association was strongest in the highest intake quintile. The signal was weaker in postmenopausal women, hinting at an estrogen-dependent component.
Observational and cross-sectional. Cannot establish that silicon supplementation increases bone density — only that intake correlates with it across a population. Diet patterns rich in silicon (whole grains, beer) carry many other nutrients.
Choline-stabilized orthosilicic acid in osteopenic women
mixed · RCT
Spector et al., 2008, BMC Musculoskeletal Disordersn=136Industry-fundedPostmenopausal women on calcium and vitamin D received added ChOS at three doses for 12 months. Markers of bone formation rose modestly with silicon vs placebo, and femoral bone mineral density showed a small advantage. The clinical magnitude is small and the trial is one of the few in this space.
Industry-funded (BioSil manufacturer). Modest absolute effects; bone formation markers are intermediate rather than fracture endpoints.
Hair strength and thickness
Mechanism
Silicon contributes to disulfide cross-linking in keratin and supports the connective-tissue matrix around the hair follicle. Bioavailable forms reach plasma and are detectable in hair shaft over time.
The strongest hair data is one small trial (n=48) of 10 mg/day silicon as ChOS over nine months in women with fine hair, showing improvements in tensile strength, elasticity, and shaft thickness. Industry-funded, narrow population, and never replicated independently. The signal is plausible but not robust enough to position silicon as a hair-loss intervention.
Most useful as part of a connective-tissue-support strategy for women with thin or fragile hair. Not an alternative to evidence-backed hair therapies (minoxidil, finasteride) for pattern hair loss.
Choline-stabilized orthosilicic acid for hair quality
positive · RCT
Barel et al., 2005, Archives of Dermatological Researchn=48Industry-fundedForty-eight women with fine hair took 10 mg/day silicon as ChOS for nine months. Hair tensile strength and elasticity improved compared with placebo, and hair shaft cross-section thickened slightly. A small but characterized signal in the form most studied.
Small sample, narrow population (women with self-reported fine hair), and industry-funded. The mechanism — silicon contributing to disulfide cross-linking and connective tissue — is plausible but not proven.
Skin elasticity and texture
Mechanism
Silicon supports the cross-linking of collagen and glycosaminoglycans in the dermal matrix. Orthosilicic acid is the bioavailable form; the cheap silica/silicon dioxide form in most multivitamins is poorly absorbed.
One small 20-week trial of 10 mg/day silicon as ChOS in women with photoaged skin showed modest improvements in skin roughness and elasticity. Industry-funded, small sample, single research group. The effects are modest and the evidence base is thin compared to the established skin ingredients (collagen peptides, hyaluronic acid).
An adjunct, not a primary skin ingredient. Form matters — silicon dioxide in a multivitamin will not reproduce the trial conditions.
Choline-stabilized orthosilicic acid for skin
positive · RCT
Barel et al., 2005 (companion analysis), Archives of Dermatological Researchn=50Industry-fundedWomen with photoaged skin took 10 mg/day silicon as ChOS for 20 weeks. Skin roughness improved and elasticity measurements rose modestly compared with placebo. The trial is small and the effect sizes are clinically modest.
Industry-funded; small sample; mechanistic plausibility (silicon's role in glycosaminoglycan and collagen cross-linking) is suggestive rather than established.
General health
Mechanism
Silicon is found in whole grains, beer, certain mineral waters, leafy vegetables, and some fruits. It is not classified as essential for humans, but the nutritional and observational data suggest a modest functional role in connective tissue.
Average dietary silicon intake in Western populations sits around 20–50 mg/day, mostly from grains and beverages. There is no characterized human deficiency syndrome. Whole-diet patterns associated with higher silicon intake also tend to be richer in fiber and other micronutrients, which complicates causal interpretation.
Not a standalone nutrient priority for general health. Adequate intake is achieved through ordinary dietary patterns.
Dietary silicon and bone mineral density (Framingham)
positive · Observational
Jugdaohsingh et al., 2004, Journal of Bone and Mineral Researchn=2847Higher dietary silicon intake was associated with higher hip bone mineral density in men and premenopausal women in the Framingham Offspring cohort. The association was strongest in the highest intake quintile. The signal was weaker in postmenopausal women, hinting at an estrogen-dependent component.
Observational and cross-sectional. Cannot establish that silicon supplementation increases bone density — only that intake correlates with it across a population. Diet patterns rich in silicon (whole grains, beer) carry many other nutrients.
4 forms of Silica compared
Orthosilicic acid
High — the bioavailable circulating form
Best forThe reference form for absorptionPure orthosilicic acid is unstable in solution, which is why most supplement-grade product uses a stabilized variant such as ChOS.
BioSil
Choline-stabilized orthosilicic acid (ChOS)
High — the form used in the Barel and Spector trials
Best forHair, skin, and bone support — the studied silicon formAll four cited trials used this form. The industry-funded label applies, but it is the only form with characterized bioavailability and clinical trial data.
hair10–10 mgskin10–10 mgbone6–24 mgSilicon dioxide / silica
Poor — most ingested silica passes through unabsorbed
Best forCheap multivitamin filler form; functions partly as an excipientIf a label says '10 mg silicon (as silicon dioxide)' you should not assume it reproduces the ChOS trial data. The clinical trials used soluble forms, not the inert dioxide.
Horsetail (Equisetum arvense) extract
Variable — dependent on extract preparation and silicate solubility
Best forBotanical silicon source in hair and skin formulasSilicon content varies widely across products. Long-term safety has thiaminase concerns at high botanical doses; standard extracts processed to remove thiaminase are commonly used.
Are you deficient? Symptoms, risk groups, lab tests
Silicon is not classified as essential for humans, and no clear deficiency syndrome has been characterized. Average Western dietary intake is around 20–50 mg/day from whole grains, beer, mineral water, and some plant foods.
Common symptoms
- No characterized human deficiency syndrome
Who is at risk
Adults on highly processed diets
Refining grain reduces silicon content. Whole-grain-poor diets pair lower silicon intake with lower fiber and micronutrient density more broadly.
Postmenopausal women with osteopenia (theoretical)
The Framingham observation that the silicon-bone association is strongest in pre-menopausal women raises a hypothesis about estrogen-dependent silicon utilization. Not a deficiency state per se, but a population where the small trial data is most relevant.
Lab markers
Serum or urinary silicon
Not part of routine clinical assessment. Reflects recent intake more than tissue status. Useful only in research contexts.
Side effects and drug interactions
Side effects
Gastrointestinal upset
Uncommon
Mild GI symptoms have been reported at high botanical doses; ChOS at 10 mg/day has been well tolerated in trials.
Kidney stone risk (theoretical)
Rare · Reported at sustained intakes well above standard supplemental dosing
Long-term very high silicon intake from certain mineral waters has been linked to silica-containing kidney stones in case reports. Not a concern at typical supplement doses.
Drug interactions
Other
No clinically significant drug interactions are well established at typical supplemental doses.
Routine clinical review is not required for supplemental silicon at the doses used in retail products.
Other critical caveats
- Form matters more than label dose. The silicon dioxide / silica filler in most multivitamins is poorly absorbed and will not reproduce the trial conditions used to establish the modest hair, skin, and bone signals.
- All published clinical evidence for hair, skin, and bone benefit uses choline-stabilized orthosilicic acid (ChOS) — the BioSil branded form — and the trials are small and industry-funded. Independent replication is limited.
- Silicon is not classified as essential for humans. The supplementation case is about modest support for connective tissue, not addressing a deficiency.
Frequently asked
Is silicon worth supplementing for hair or skin?
Maybe, with caveats. The choline-stabilized orthosilicic acid (ChOS, BioSil) trials show small improvements in hair strength and skin elasticity at 10 mg/day over several months. The trials are small and industry-funded. It is a reasonable adjunct alongside collagen or established hair-loss therapies, not a standalone solution.Is the silicon in my multivitamin doing anything?
Probably not much. Most multivitamins use silicon dioxide or silica, which is poorly absorbed. The clinical-trial data uses soluble orthosilicic acid forms. If you specifically want the trial-tested benefit, look for ChOS or stabilized orthosilicic acid on the label.Can I get silicon from food?
Yes — whole grains (especially oats, barley), beer, mineral water (depending on source), green beans, bananas, and some leafy greens are notable sources. Average Western intake is around 20–50 mg/day. There is no characterized deficiency syndrome from low intake alone.How much silicon should I take?
The trials used 6–24 mg/day for bone and 10 mg/day for hair and skin, all as ChOS. There is no official RDA because silicon is not classified as essential. The safe upper bound has not been firmly established for supplements; sustained intakes far above dietary patterns warrant caution.What about horsetail extract?
Horsetail is a traditional silicon-containing botanical, and some hair and nail formulas use it. Silicon content varies widely between products and the trial data is for ChOS, not horsetail. Standard extracts processed to remove thiaminase are generally safe at typical doses; long-term high-dose use has not been well studied.
References
- 01NIH Office of Dietary Supplements — Silicon (Dietary Reference Intakes)
- 02Linus Pauling Institute — Silicon
Last reviewed2026-05-07