Silica (Silicon)
Summary
Silicon supplements are sold for hair, skin, nails and bones. In a 9-month trial of 48 women, 10 mg/day of silicon (as ch-OSA) made hair thicker and less prone to breakage (grade D). In women with low bone density it raised a bone-formation marker but not spine bone density, and a knee osteoarthritis trial found no overall effect. Most trials were funded by the maker of ch-OSA.
Key facts
- A trace element; supplements use stabilized orthosilicic acid (ch-OSA, OSA-vanillin) or monomethylsilanetriol (MMST)[1][6]
- Hair strength and thickness (D); bone markers with calcium and vitamin D (mixed, D); knee osteoarthritis (no overall effect, C)[4][2][3]
- EFSA (2016): MMST at about 7–10 mg silicon/day in supplements raises no safety concern; it did not set a safe amount of silicon itself[1]
- Bio Minerals NV, which makes ch-OSA (BioSil), funded or staffed the bone, knee and dental-implant trials; an OSA-vanillin study included DexSil Labs authors[2][3][5][6]
- 5 graded human outcomes on this page
- October 10, 2026
How it works
ProposedOrthosilicic acid is the form of silicon found in food and water and the form absorbed from the gut; stabilized supplements aim to keep it from clumping into poorly absorbed polymers. A role in collagen and connective tissue is proposed but not established.[6][1][2]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Joints | Grade C | No effect | RCT · n = 211 · 2017 | 1 row |
| Bone | Grade D | Mixed | RCT · n = 184 · 2008 | 1 row |
| Hair | Grade D | Improved | RCT · n = 48 · 2007 | 1 row |
| Safety | Grade D | No effect | Crossover RCT · n = 22 · 2013 | 1 row |
| Dental | Grade D | Mixed | Pilot RCT · n = 21 · 2021 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Knee osteoarthritis pain and function (WOMAC) | No effect | Grade C | RCT · n = 211 · 2017 Adults with knee osteoarthritis (Kellgren-Lawrence grade II–III) and moderate pain Form: ch-OSA · Dose: Dose not stated in the abstract · Duration: 12 weeks No difference from placebo in pain, function or cartilage biomarkers in the whole group; a pre-specified analysis by sex showed improvements in men only. 166 of 211 randomized were analyzed. | 28056936 (opens PubMed)Source [3] |
| Bone formation markers and bone density | Mixed | Grade D | RCT · n = 184 · 2008 Women with osteopenia (spine T-score below −1.5) taking calcium and vitamin D3 Form: ch-OSA added to 1,000 mg calcium and 20 mcg vitamin D3 · Dose: 3, 6 or 12 mg silicon/day · Duration: 12 months Only the collagen-formation marker PINP rose significantly (6 and 12 mg) versus placebo, without a clear dose response; lumbar spine bone density did not change; a post-hoc femoral-neck gain appeared at 6 mg. 136 of 184 women completed the study. | 18547426 (opens PubMed)Source [2] |
| Hair strength and thickness | Improved | Grade D | RCT · n = 48 · 2007 Women with fine hair Form: Choline-stabilized orthosilicic acid (ch-OSA) beadlets · Dose: 10 mg silicon/day · Duration: 9 months Hair cross-sectional area increased from baseline with ch-OSA but not placebo; elasticity and break load fell less than with placebo. | 17960402 (opens PubMed)Source [4] |
| Silicon levels and safety markers | No effect | Grade D | Crossover RCT · n = 22 · 2013 Healthy premenopausal women Form: Monomethylsilanetriol (MMST) · Dose: 10.5 mg silicon/day · Duration: 4 weeks per period MMST raised fasting serum and urine silicon, with no reported adverse effects or blood chemistry changes versus placebo. | 23622499 (opens PubMed)Source [7] |
| Bone around dental implants (peri-implantitis) | Mixed | Grade D | Pilot RCT · n = 21 · 2021 Adults with peri-implantitis Form: ch-OSA capsules · Dose: Twice daily (dose not stated in the abstract) · Duration: 12 months Pocket depth and bleeding improved in both groups; implant bone-level measures stayed stable with ch-OSA but worsened with placebo. 18 people were in the per-protocol analysis. | 34587941 (opens PubMed)Source [5] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Choline-stabilized orthosilicic acid (ch-OSA) | Varies[2][1] | Raised urinary silicon in supplemented women, indicating absorption.[4] | No ch-OSA-related adverse events and normal safety blood tests over 12 months.[2] | Hair, bone, knee and dental-implant trials |
| Monomethylsilanetriol (MMST, "organic silicon") | Varies[2][1] | Raised serum and urine silicon over 4 weeks; EFSA concluded orthosilicic acid is released and silicon is bioavailable.[7][1] | No adverse effects in a 4-week trial; EFSA found no safety concern at about 7–10 mg silicon/day.[7][1] | Safety and absorption studies |
| Orthosilicic acid-vanillin complex (OSA-VC) | Varies[2][1] | About 21% of the silicon was excreted in urine within 6 hours.[6] | No tolerance data in the abstract.[6] | Absorption study |
Studied doses
Doses studied in human trials ranged from 3 to 12 mg of silicon per day as ch-OSA for 12 months in a bone trial, with 10 mg/day for 9 months in a hair trial and 10.5 mg/day as MMST for 4 weeks.[2][4][7]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Other supplements
- Calcium and vitamin DRCTSilicon was tested as an add-on to calcium and vitamin D3 in the bone trial, with no safety problems reported.[2]
Who should be careful
- People expecting bone-density gains
- In the main bone trial, spine bone density did not improve versus calcium and vitamin D alone.[2]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Safety
Silicon at supplement doses has shown few safety issues in trials.
How to read the label
- Silicon vs product weightCheck the silicon content per serving (studies used 3–12 mg), not the weight of silica or the carrier.[2][4]
- Form mattersStabilized orthosilicic acid and MMST are absorbed; EFSA assessed MMST at about 7–10 mg silicon/day.[1][6]
- Brand-funded evidenceMost ch-OSA trials were funded by its maker, so results should be read with that in mind.[2][3][5]
Cost per studied dose, without the sales pitch
Compare any product you already have by the amount it delivers, not by capsule count or front-of-pack weight.
Cost per studied dose
Enter the price, servings and the amount per serving from your label.
Frequently asked questions
Does silica help hair growth?
In a 9-month trial of 48 women with fine hair, 10 mg/day of silicon as ch-OSA made hair thicker and stronger, but it did not measure growth.[4]
Does silicon strengthen bones?
With calcium and vitamin D, it raised a bone-formation marker but did not improve spine bone density over 12 months.[2]
Does silica help knee arthritis?
A 12-week trial in 211 adults found no overall effect; benefits appeared only in men in a pre-specified analysis by sex.[3]
Sources
- [1]Safety of organic silicon (monomethylsilanetriol, MMST) as a novel food ingredient for use as a source of silicon in food supplements and bioavailability of orthosilicic acid from the source (EFSA Journal 2016;14(4):4436). European Food Safety Authority (EFSA) ANS Panel, 2016. guideline
- [2]Choline-stabilized orthosilicic acid supplementation as an adjunct to calcium/vitamin D3 stimulates markers of bone formation in osteopenic females: a randomized, placebo-controlled trial.. BMC Musculoskelet Disord, 2008. RCT
- [3]A 12-week randomized, double-blind, placebo-controlled multicenter study of choline-stabilized orthosilicic acid in patients with symptomatic knee osteoarthritis.. BMC Musculoskelet Disord, 2017. RCT
- [4]Effect of oral intake of choline-stabilized orthosilicic acid on hair tensile strength and morphology in women with fine hair.. Arch Dermatol Res, 2007. RCT
- [5]The effect of choline-stabilized orthosilicic acid in patients with peri-implantitis: an exploratory randomized, double-blind, placebo controlled study.. BMC Oral Health, 2021. pilot-RCT
- [6]Digestive absorption of silicon, supplemented as orthosilicic acid-vanillin complex.. Mol Nutr Food Res, 2015. PK-study
- [7]The silicon supplement 'Monomethylsilanetriol' is safe and increases the body pool of silicon in healthy Pre-menopausal women.. Nutr Metab (Lond), 2013. crossover-RCT
- [8]There are not enough data to conclude that Monomethylsilanetriol is safe.. Nutr Metab (Lond), 2013. review
- [9]Silicon Supplementation for Bone Health: An Umbrella Review Attempting to Translate from Animals to Humans.. Nutrients, 2024. systematic-review
What changed
- First draft. Every PMID checked against NCBI E-utilities esummary (title and year taken from the record) and abstracts read for the cited rows.
- Adversarial review pass: every evidence row re-read against its PubMed abstract. Official source opened before citing: EFSA opinion on organic silicon (MMST) as a source of silicon in food supplements (2016). The EFSA 2009 ch-OSA opinion page was opened but shows no abstract, so it is not cited. No NIH ODS or NCCIH fact sheet covers silicon. Industry ties: Bio Minerals NV (ch-OSA maker) funded the bone (PMC2442067) and knee (PMC5217239) trials and employs authors of the knee and implant trials; DexSil Labs authors on the OSA-vanillin study; the MMST critique was written by the ch-OSA developer. The 2005 ch-OSA skin, hair and nails trial (16205932) carries two errata and was excluded. Retraction, expression-of-concern, erratum and withdrawn checks on all 8 PMIDs: none flagged. Page set indexable. Independent browser review (4 parallel reviewers, every evidence row checked against its abstract and official sources on the Vercel preview) found issues that were fixed: evidence direction now follows the site convention (up = improved, down = worsened), plus wording and disclosure corrections listed in the batch-14 PR review comment.