silica
Silicon (delivered as silica, orthosilicic acid, or plant-derived sources) is a trace element with structural roles in bone matrix and connective tissue. Two small RCTs — Spector 2008 on bone, Wickett 2007 on hair — found measurable but modest effects of choline-stabilized orthosilicic acid. Both were industry-funded. The 'beauty mineral' marketing dramatically outruns the actual clinical evidence.
Quick decision guide
May help most
Postmenopausal women with osteopenia who want a low-risk adjunct to calcium/vitamin D and standard osteoporosis care; women with fine, brittle hair willing to commit to 6–9 months of daily use with realistic expectations.
Common dosing range
5–10 mg elemental silicon/day from choline-stabilized orthosilicic acid (ch-OSA), or 20–40 mg/day from plant-derived bamboo or horsetail extracts standardized to silicon content.
When to expect effects
Months — Spector used 12 months for bone biomarkers; Wickett used 9 months for hair tensile strength.
Watch out for
Long-term horsetail (Equisetum) use can deplete thiamine (B1) via its thiaminase content; choose thiaminase-removed extracts. Avoid silica-aerogel inhalation; oral silica is fine.
Evidence snapshot
What is it
Silica refers to silicon dioxide (SiO2), but in nutrition contexts often refers to silicon, the second most abundant element in the Earth's crust. Silicon in soluble forms (orthosilicic acid) is a trace nutrient present in the human body, with roles in connective tissue, bone, and cartilage.
Is it worth it for you?
Use this as a quick fit check, not a diagnosis.
Worth considering if…
Probably skip if…
Evidence at a glance
| Goal | Effect | Best fit | Time |
|---|---|---|---|
Bone density (adjunct in osteopenia) Limited Evidence | Femoral neck BMD trend +1.2% over 12 months at 6 mg Si/day; dose-related rise in PINP; no significant change at lumbar spine | Postmenopausal women with osteopenia (T-score -1.0 to -2.4) already on calcium/vitamin D; people who want a low-risk add-on while assessing whether to start prescription osteoporosis therapy | 12 months for measurable BMD/biomarker change |
Hair tensile strength and thickness Limited Evidence | Significant improvement in hair tensile strength and elasticity at 9 months; small increase in fibre cross-sectional area | Women with naturally fine, brittle hair seeking modest improvement in fibre strength | 9 months |
Skin elasticity and wrinkles Mixed Evidence | Inconsistent micro-improvements in skin elasticity/micro-relief in short trials; no robust replication | Adults curious to try a low-risk daily supplement alongside sun protection and a good skincare routine | Not reliably established |
Nail strength Mixed Evidence | Anecdotal/open-label reports of reduced brittleness; no controlled clinical-endpoint data | None — try biotin or correct iron first if applicable | Not established |
Bone density (adjunct in osteopenia)
- Effect
- Femoral neck BMD trend +1.2% over 12 months at 6 mg Si/day; dose-related rise in PINP; no significant change at lumbar spine
- Best fit
- Postmenopausal women with osteopenia (T-score -1.0 to -2.4) already on calcium/vitamin D; people who want a low-risk add-on while assessing whether to start prescription osteoporosis therapy
- Time
- 12 months for measurable BMD/biomarker change
Hair tensile strength and thickness
- Effect
- Significant improvement in hair tensile strength and elasticity at 9 months; small increase in fibre cross-sectional area
- Best fit
- Women with naturally fine, brittle hair seeking modest improvement in fibre strength
- Time
- 9 months
Skin elasticity and wrinkles
- Effect
- Inconsistent micro-improvements in skin elasticity/micro-relief in short trials; no robust replication
- Best fit
- Adults curious to try a low-risk daily supplement alongside sun protection and a good skincare routine
- Time
- Not reliably established
Nail strength
- Effect
- Anecdotal/open-label reports of reduced brittleness; no controlled clinical-endpoint data
- Best fit
- None — try biotin or correct iron first if applicable
- Time
- Not established
Evidence for 4 uses
AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.
Bone density (adjunct in osteopenia)
Disease adjunctSpector 2008 randomized 136 osteopenic postmenopausal women to choline-stabilized orthosilicic acid (ch-OSA) at 3, 6, or 12 mg silicon/day plus calcium and vitamin D, vs calcium/vitamin D alone, for 12 months. Femoral neck BMD trended ~1.2% higher in the ch-OSA arms, and procollagen type 1 N-terminal propeptide (PINP, a bone-formation marker) rose dose-dependently. Lumbar spine BMD didn't differ significantly. The effect is modest, industry-funded, and not replicated in larger independent trials — but it's the best human evidence in the silicon-and-bone literature.
Bottom line: Real but small benefit on hip biomarkers and a trend on BMD. An adjunct, not a replacement for proven osteoporosis treatments.
Hair tensile strength and thickness
Supplement benefitWickett 2007 gave 48 women with fine hair ch-OSA 10 mg silicon/day or placebo for 9 months. Hair tensile strength and elasticity improved significantly in the ch-OSA group; cross-sectional hair thickness rose modestly. The trial was industry-sponsored and small — it shows a measurable effect but doesn't generalise to hair loss (alopecia) or other hair conditions. There's no good data on hair regrowth from silicon.
Bottom line: Modest, measurable improvement in hair fibre strength after most of a year. Don't expect new hair growth — that's a different physiology.
Skin elasticity and wrinkles
Supplement benefitSmall open-label and short-term placebo-controlled studies have measured changes in skin micro-relief, hydration, or elasticity with oral silicon supplements (ch-OSA, bamboo silica, horsetail). The effects are inconsistent and the trials are small, brief, and largely industry-sponsored. Topical silicon products have separate (and even weaker) evidence. The mechanism (silicon contributing to collagen cross-linking) is plausible but the human clinical signal is preliminary.
Bottom line: Plausible mechanism, weak clinical data. Sunscreen and topical retinoids have dramatically better skin-aging evidence.
Nail strength
Supplement benefitOften marketed alongside hair claims, nail benefits from oral silicon have only thin clinical support — a couple of small open-label observations of reduced brittleness over months. Biotin has stronger (though still limited) evidence for nails; iron correction for iron-deficient adults outperforms either. Don't choose silicon as a primary nail-strength supplement.
Bottom line: Don't buy silicon specifically for nails. Biotin has slightly more evidence; iron correction trumps both.
How it works
How to take it
What to track
Bottom line: Pick ch-OSA at 5–10 mg silicon/day if you can; commit to at least 6 months. Don't expect dramatic results in weeks.
6 commercial forms
Compare the main delivery options and what they’re best suited for.
Choline-stabilized orthosilicic acid (ch-OSA)
Best studiedStabilised liquid OSA bound to choline; the form used in both the Spector 2008 bone trial and the Wickett 2007 hair trial. Available as drops added to water or as small capsules. Branded as BioSil and similar.
Best characterised oral bioavailability of any silicon form.
Orthosilicic acid (OSA), other stabilisations
BioavailableNon-choline-stabilised OSA preparations exist; bioavailability is generally comparable to ch-OSA over short periods. Less clinical-trial data attached to specific products.
Similar absorption to ch-OSA; fewer trials.
Bamboo extract (silica-rich)
Plant-derivedBamboo shoots contain ~70% silica by dry weight. Supplements typically supply 20–40 mg silicon/day. No published RCTs on bamboo silica specifically; assumed similar in mechanism to other plant-silicon sources.
Lower than OSA; partly silicon released from plant matrix.
Horsetail (Equisetum arvense) extract
Use cautiouslyTraditional silicon source. Contains thiaminase that can degrade vitamin B1 — long-term use should be a thiaminase-removed extract or otherwise standardised for safety. Pyrrolizidine alkaloid content is generally low in E. arvense but choose tested brands.
Variable; depends heavily on extraction.
Bulk silicon dioxide capsules
AvoidCheap capsules listing hundreds of mg of SiO₂ deliver poor elemental silicon — most passes through unchanged. Used in supplement formulations as an excipient (flow agent), not as a meaningful active.
Very low oral bioavailability — most is excreted unchanged.
Colloidal silica / silica gel (drinks)
NicheLiquid colloidal silica products are marketed as 'living silica.' Bioavailability sits between ch-OSA (high) and bulk SiO₂ (low). No comparative RCT data.
Intermediate; depends on particle size and stabilisation.
Safety
Know the common side effects, key cautions, and who should avoid it.
Common side effects
Serious risks
Long-term horsetail (Equisetum arvense) extracts contain thiaminase that can deplete thiamine (vitamin B1) — choose products explicitly labeled 'thiaminase removed' or use a different silicon form.
Inhaled crystalline silica (sandblasting, mining dust) causes silicosis and lung cancer — this is an occupational hazard, not an oral-supplement risk. Oral silicon supplements are not the same exposure route.
Who should avoid it
- Children — there's no human dosing data and no demonstrated need for supplemental silicon in pediatric nutrition.
- People with kidney impairment — silicon is renally excreted; without studies in chronic kidney disease, avoid supplementing without a nephrologist.
- Pregnant or breastfeeding women if using horsetail extract (alkaloid and thiaminase concerns). ch-OSA at intake-equivalent doses hasn't been formally studied in pregnancy — avoid unless your clinician advises otherwise.
Pregnancy & breastfeeding
Dietary silicon intake (20–50 mg/day from food) is unchanged in pregnancy and considered safe. Supplemental silicon — especially horsetail — hasn't been formally studied in pregnant or breastfeeding women and should be avoided unless your obstetric provider explicitly approves a specific product. ch-OSA at supplemental doses likewise lacks pregnancy safety data.
Bottom line: Oral silica is very low-risk at typical supplement doses. Beware horsetail's thiaminase content for long-term use; never inhale silica dust.
Interactions
Horsetail (Equisetum) contains thiaminase, which can degrade B1 over long-term use. Use a thiaminase-removed extract or a different silicon source.
No specific clinical interaction reported, but bisphosphonates are sensitive to co-ingested cations and food — separate any silicon supplement from your bisphosphonate dose by the same window your prescription requires (typically 30–60 min before food/other oral meds).
Aluminum from antacids can bind silicate in the gut; net silicon absorption may be reduced. Not clinically important at typical doses.
Protocols featuring silica
Evidence-backed routines where silica plays a role.
Food sources
| Food | Amount | %DV |
|---|---|---|
| Beer (silicon-rich barley wort) | 1 can (~6–10 mg Si) | — |
| Whole grain bread / oats / brown rice | 1 serving (~3–7 mg Si) | — |
| Bananas | 1 medium (~5 mg Si; ~4% absorbed) | — |
| Green beans (cooked) | ½ cup (~3 mg Si) | — |
| Spinach (raw) | 1 cup (~1 mg Si) | — |
| Mineral water (silica-rich brands) | 1 L (~30–50 mg Si depending on source) | — |
| Coffee (brewed) | 1 cup (~2 mg Si) | — |
Beer (silicon-rich barley wort)
- Amount
- 1 can (~6–10 mg Si)
- %DV
- —
Whole grain bread / oats / brown rice
- Amount
- 1 serving (~3–7 mg Si)
- %DV
- —
Bananas
- Amount
- 1 medium (~5 mg Si; ~4% absorbed)
- %DV
- —
Green beans (cooked)
- Amount
- ½ cup (~3 mg Si)
- %DV
- —
Spinach (raw)
- Amount
- 1 cup (~1 mg Si)
- %DV
- —
Mineral water (silica-rich brands)
- Amount
- 1 L (~30–50 mg Si depending on source)
- %DV
- —
Coffee (brewed)
- Amount
- 1 cup (~2 mg Si)
- %DV
- —
Choosing a product
What to look for on the label — and what to be skeptical of.
Look for…
Be skeptical of…
Frequently asked questions
Is silica an essential nutrient?⌄
Silicon (the elemental form of silica) is considered a possibly essential ultratrace nutrient. While the body contains and uses silicon, no human deficiency syndrome has been definitively established, and no RDA exists.
Which silica form is best absorbed?⌄
Soluble orthosilicic acid and its stabilized forms (choline-stabilized OSA) are best absorbed. Insoluble silicon dioxide and most plant-derived silica supplements are poorly absorbed unless specifically processed.
Does silica help with hair and nails?⌄
Some clinical trials of ch-OSA show modest improvements in hair and nail strength over months of use. Effects are gradual; magic claims about rapid hair growth are not supported.
Is silica from horsetail effective?⌄
Most horsetail-based silica is in insoluble forms that are poorly absorbed. Some manufacturers process horsetail to increase bioavailability; quality varies. Look for products with documented bioavailability data.
Can I get enough silica from food?⌄
Average dietary silicon intake (20 to 50 mg/day) is generally adequate. Beer, mineral water, whole grains, and certain vegetables are good sources. Supplementation may benefit specific applications like bone or skin support.
References by claim
Bone density (adjunct in osteopenia)
Spector et al., 2008 — PubMed — BMC Musculoskeletal Disorders (2008) link
Hair tensile strength and thickness
Wickett et al., 2007 — PubMed — Archives of Dermatological Research (2007) link
Skin elasticity and wrinkles
Jugdaohsingh, 2007 — PMC — Journal of Nutrition, Health & Aging (2007) link
Safety
EFSA Opinion on Silicon (2004) — European Food Safety Authority (2004) link
Track silica with Pilora
Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.
Coming to App StoreDisclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.