Silicon (orthosilicic acid) · mineral
Evidence tier: limited
A foundational connective tissue mineral for hair, skin, nails, and bones. Most Western diets are marginally low.
The proposed mechanism is that bioavailable silicon, absorbed as orthosilicic acid, participates in the cross linking and maturation of collagen and in the mineralisation of bone matrix. Animal work supports a role in connective tissue, and orthosilicic acid stimulates collagen type I synthesis in cultured cells. In people the mechanism gets as far as a bone formation marker and no further: it has not been shown to translate into denser bone, and the collagen story has not been shown to translate into measurably better hair or nails against placebo. Form matters more than dose here: most dietary and supplemental silica (including horsetail and bamboo derived powders) is poorly absorbed, and orthosilicic acid is the form the trials used.
Limited, and the limit is sharper than the beauty aisle admits. Silicon is not an essential nutrient in the way iron or selenium are: no human deficiency syndrome has been defined, no RDA has been set, and typical Western dietary intake already runs 20 to 50 mg of silicon per day from grains, beer and plants. The human trial evidence is small, and it is almost entirely on ONE proprietary form, choline stabilised orthosilicic acid, funded by the company that makes it. HAIR, SKIN AND NAILS: the cited trial is Barel 2005 (PMID 16205932), a randomised double blind placebo controlled study of 50 women with photodamaged facial skin taking 10 mg of silicon daily for 20 weeks. Skin roughness improved against placebo. But read the hair and nail result carefully, because it is the whole claim: brittleness scores were significantly lower after 20 weeks in the ch OSA group COMPARED TO BASELINE, that is a within group before and after change, self rated on a visual analogue scale, not a demonstrated win over placebo. That is not evidence that silica grows hair or hardens nails, and 50 women in a manufacturer supported trial is not a literature. BONE: the larger trial (Spector 2008, PMID 18547426) randomised 184 osteopenic women to calcium and vitamin D3 plus placebo or plus 3, 6 or 12 mg of silicon for 12 months. Lumbar spine bone mineral density DID NOT CHANGE SIGNIFICANTLY. What moved was PINP, a bone formation MARKER, at some doses, with no clear dose response. A marker moving while the bone density does not is a surrogate outcome, and surrogate outcomes are how weak supplements are made to look strong. There is no NCCIH page, no Cochrane review and no regulatory monograph for silicon supplementation. The safety picture is reassuring for the ORAL form, which is well tolerated and excreted renally, and must never be confused with INHALED crystalline silica, which causes silicosis and is a lung carcinogen. Those are the same element and completely different exposures.
The trials used 6 to 12 mg of silicon daily as choline stabilised orthosilicic acid, with 10 mg daily for 20 weeks in the skin trial. Ordinary diet already supplies 20 to 50 mg of silicon daily, though in poorly absorbed forms. No RDA and no upper limit have been established for silicon.
5 to 10 mg choline stabilised orthosilicic acid daily, or 20 to 30 mg horsetail derived. With food.
Onset: ~140 days
Generally very safe at supplemental doses. Avoid horsetail derived sources in vitamin B1 deficiency.
Pregnancy: caution
Breastfeeding: caution
Active compounds: orthosilicic acid, choline stabilised orthosilicic acid
Remedies using Silica · Browse by body system · Check it against what you take
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.