Orthosilicic Acid: The Silicon Supplement That Actually Has Skin Trials
Most “beauty from within” supplements are long on marketing and short on trials. Orthosilicic acid is an unusual exception: the specific choline-stabilised form has a couple of proper randomised trials behind it for skin, hair and nails. The effect is modest and the evidence has real limits — but for once there is evidence to weigh, and this guide weighs it.
Quick Answer
Choline-stabilised orthosilicic acid (ch-OSA, sold as Biosil) is a bioavailable form of dietary silicon. In a randomised placebo-controlled trial, 10 mg of silicon a day for 20 weeks measurably improved skin surface and elasticity and reduced hair and nail brittleness in women with sun-damaged skin. The effect is real but modest, the trials are small and largely tied to the manufacturer, and only this specific ch-OSA form — not generic “silica” — carries the evidence. It is one of the better-supported ingestibles for skin firmness, well short of a retinoid.
What Orthosilicic Acid Is
Silicon is a trace element involved in building and maintaining connective tissue. In the body it plays a role in the synthesis of collagen and glycosaminoglycans — the structural scaffold and water-holding molecules of the dermis. The catch is that most dietary silicon is poorly absorbed. Orthosilicic acid is the small, soluble, bioavailable form the body can actually take up, and choline-stabilised orthosilicic acid (ch-OSA) is a manufactured version engineered to stay stable and absorbable; it is the form sold as Biosil and the form used in the clinical trials. That distinction matters more than almost anything else on this page.
What the Trials Show
The key skin study is Barel and colleagues (2005, Archives of Dermatological Research): 50 women with photodamaged facial skin took either 10 mg of silicon a day as ch-OSA or a placebo for 20 weeks. The ch-OSA group showed a significant improvement in skin surface roughness and in skin mechanical properties (elasticity), along with reduced brittleness of hair and nails, while serum silicon rose by more than 90 percent — confirming the form was genuinely absorbed. A separate randomised trial (Wickett 2007) gave 48 women with fine hair the same 10 mg of silicon a day for nine months and reported improved hair tensile strength and morphology. Two proper RCTs, both pointing the same way, is more than most supplements in this category can claim.
The Honest Caveats
The evidence is real but it is not large or independent. The trials are small (dozens, not hundreds, of participants), and the research is closely associated with the group and manufacturer behind ch-OSA, which is the same industry-funding pattern that shadows most beauty-supplement science. The effect sizes are modest — a measurable reduction in surface roughness and a firmer feel, not a visible transformation — and they emerge only over months, not weeks. None of that makes the findings wrong; it means ch-OSA earns a “modest but genuinely supported” rating rather than a glowing one.
Established vs. Overstated
| Claim | Evidence Strength | What the data shows | Status |
|---|---|---|---|
| Improves skin elasticity and surface | Moderate | Barel 2005 RCT (n=50, 20 weeks): significant vs placebo on roughness and mechanical properties | Supported (modest) |
| Strengthens hair and nails | Moderate | Wickett 2007 hair RCT plus reduced hair/nail brittleness in Barel 2005 | Supported (modest) |
| Is well absorbed | Strong | Serum silicon rose over 90% on ch-OSA in Barel 2005 | Established |
| Any “silica” supplement does the same | Absent | Only the ch-OSA (Biosil) form was trialled; horsetail and colloidal silica are untested here | Overstated |
How to Use It
The trials used 5 to 10 mg of elemental silicon a day as ch-OSA, taken with food, over a 20-week horizon for skin and up to nine months for hair. Biosil is the specific branded form that carries the clinical data. Because the effect is slow and subtle, judging it before a few months have passed is judging it too early. The risk profile is low and it is generally well tolerated.
Who It's For, and Who Should Be Cautious
The natural candidate is someone with mature or sun-exposed skin who wants an ingestible with actual trial support for firmness and connective-tissue quality, and who holds realistic expectations about a modest, gradual effect. It also appeals to anyone chasing the hair-and-nail benefits. It is well tolerated in the studies; as with any supplement, pregnancy and breastfeeding data are limited, which argues for the usual caution, and it is worth choosing the studied ch-OSA form rather than a generic silica product.
Pairs Well With / Avoid Combining
Commonly stacked with: Collagen and Biotin — the pairings in our catalogue share a “structural support” logic (collagen as beauty-from-within protein, biotin for keratin) that overlaps neatly with silicon's role in connective tissue, rather than reflecting a proven combined effect.
Avoid combining with: No adverse combinations are documented for orthosilicic acid in our catalogue. As an ingestible mineral it does not conflict with topical retinoids, acids or vitamin C.
Common Myths
“All silica supplements are the same.”
No. The trials specifically used choline-stabilised orthosilicic acid (Biosil). Horsetail extract and colloidal silica are different forms with different absorption and no equivalent clinical data.
“You can just eat more silica-rich food instead.”
Dietary silicon is common but poorly absorbed — that low bioavailability is the entire reason a stabilised, absorbable form was developed and tested.
“It works like a collagen injection.”
Not remotely. ch-OSA nudges the body's own collagen and connective-tissue synthesis over months; it is a slow internal support, not a filler that adds volume on contact.
Common Questions About Orthosilicic Acid
Does orthosilicic acid actually work for skin?
Modestly, yes. A randomised placebo-controlled trial (Barel 2005) found that 10 mg of silicon a day as choline-stabilised orthosilicic acid improved skin surface and elasticity over 20 weeks in women with sun-damaged skin, which puts it ahead of most beauty supplements. The effect is small and gradual, and the studies are small and largely manufacturer-linked, so it is best read as real but modest.
Is Biosil the same as regular silica supplements?
No. The trials used choline-stabilised orthosilicic acid (ch-OSA), the specific bioavailable form sold as Biosil. Generic silica, horsetail extract and colloidal silica are different forms that are poorly absorbed and do not carry the same clinical evidence, so the studied form is the one to look for.
How long until I see results?
The skin trial measured changes at 20 weeks and the hair trial ran nine months. This is a slow connective-tissue effect, not a quick fix, so give it several months before deciding whether it is doing anything for you.
References
- Barel A, Calomme M, Timchenko A, et al. (2005). Effect of oral intake of choline-stabilized orthosilicic acid on skin, nails and hair in women with photodamaged skin. Archives of Dermatological Research.
- Wickett RR, Kossmann E, Barel A, et al. (2007). Effect of oral intake of choline-stabilized orthosilicic acid on hair tensile strength and morphology in women with fine hair. Archives of Dermatological Research.
Skin Stacker is independent: no ads, no affiliate links, no paid placement. We have no supplement to sell you and no reason to oversell ch-OSA — which is why this page credits its genuine (if small and manufacturer-linked) trials while being clear that generic “silica” supplements do not share that evidence. Reviewed / Last updated: 18 July 2026 · by JoAnn.