Also known as: Silicon, Orthosilicic acid, Bamboo extract, Horsetail extract, ch-OSA
MineralsEmerging evidence
A mineral involved in collagen formation, sold widely for hair, skin and nails. The form matters enormously, and most products use one the body can barely absorb.
Typical dose
5.0–20.0 mg per day
Daily with food; allow 3-5 months for visible change
What it is
Silicon is the element; silica is silicon dioxide, its most common natural form. Dietary sources include whole grains, beer and some vegetables.
The absorbable form in the body is orthosilicic acid. Supplements use several sources with very different absorption: bamboo extract and horsetail supply silica that is poorly absorbed, while choline-stabilised orthosilicic acid is far more bioavailable.
Bamboo extract dominates the market because it can declare an impressive silica percentage, often 70 per cent or more. That figure describes what is in the capsule rather than what reaches your bloodstream.
How it works
Silicon appears to be involved in the enzyme systems that cross-link collagen and in the early stages of bone formation, where it is found concentrated in areas of active mineralisation.
Since collagen forms the structural framework of skin, hair, nails, cartilage and bone, this is the basis for the claims made across all of them.
Silicon is not classified as an essential nutrient, and no deficiency state has been defined in humans, which limits how strongly any of this can be claimed.
What the evidence shows
The better trials have used choline-stabilised orthosilicic acid, reporting improvements in skin elasticity and roughness, and in hair and nail strength, generally over 20 weeks.
Observational research has found associations between dietary silicon intake and bone density, and small trials have reported effects on bone markers.
Trials are few, modest in size and often industry-funded, and almost all the positive findings come from the bioavailable form. Evidence for the bamboo and horsetail products that dominate retail shelves is thin.
Dosing
Trials using choline-stabilised orthosilicic acid have used 5 to 20 mg of silicon daily.
The form is the decision that matters. Compare products on elemental silicon content and on absorbability rather than on total silica weight, since a large silica figure from bamboo may deliver less usable silicon than a small figure from an absorbable source.
Effects on hair, skin and nails take time, since these tissues turn over slowly. Trials ran 20 weeks, and nails in particular grow slowly enough that three months is the minimum before judging anything. Horsetail products should be thiaminase-free, since the raw plant contains a compound that degrades vitamin B1.
Absorbed silicon clears within hours; tissue effects take months
Timing
Daily with food; allow 3-5 months for visible change
Competition status
Permitted — not on the WADA Prohibited List
Category
Minerals
Safety and side effects
Silica supplements are well tolerated at typical doses, with few adverse effects reported.
Horsetail is the one to watch. The raw plant contains an enzyme that breaks down vitamin B1, so choose products stated to be thiaminase-free, and avoid prolonged use of unprocessed horsetail.
Horsetail also has a mild diuretic effect. Speak to your doctor before use if you take regular medication or have been told your kidneys are not working normally.
Who should avoid it
Choose thiaminase-free horsetail products and avoid prolonged use of unprocessed horsetail, which degrades vitamin B1. Speak to your doctor before use if you have been told your kidneys are not working normally, or if you take regular medication. Not established at supplemental doses in pregnancy or breastfeeding.
This entry is provided for information only. Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Consult a qualified healthcare professional before use if you are pregnant, breastfeeding, taking medication or under medical supervision.
