Silicon — not to be confused with silicone (synthetic polymer) or silicon semiconductor chips — is one of the most abundant elements on Earth and the third most abundant trace element in the human body (after iron and zinc). Despite its ubiquity, silicon's role in human biology has been relatively neglected compared to other minerals — a gap that is closing as research reveals important connections between silicon intake and the health of connective tissues including bone, cartilage, skin, hair, and nails.
Silicon in biology
Silicon is present in the human body in concentrations of approximately 1-2 grams — primarily concentrated in connective tissues: bone (especially areas of active mineralization), cartilage, tendons, blood vessels (particularly the aorta), and skin, hair, and nails (Jugdaohsingh, 2007, Journal of Nutrition, Health & Aging).
The dominant dietary form of silicon is orthosilicic acid (Si(OH)₄) — a water-soluble, bioavailable form found in drinking water, beer, cereals, and certain vegetables. Orthosilicic acid is readily absorbed from the GI tract (with absorption efficiency of approximately 40-50% from water and beer, but much lower from solid foods where silicon is often bound in insoluble silicate forms).
Silicon and bone health
The strongest evidence for silicon's biological activity in humans involves bone metabolism:
The Framingham Offspring Study
The largest epidemiological study on silicon and bone was conducted using data from the Framingham Offspring cohort: Jugdaohsingh et al. (2004, Journal of Bone and Mineral Research) found that higher dietary silicon intake was positively associated with bone mineral density (BMD) at the hip — an effect that was statistically significant in men and premenopausal women but not in postmenopausal women (possibly because the estrogen-deficiency-driven bone loss overwhelms silicon's effects).
Notably, the effect of silicon on BMD was comparable in magnitude to calcium intake — suggesting silicon may be an underappreciated contributor to bone health.
Mechanisms
Silicon may support bone health through several mechanisms: silicon is concentrated at active calcification sites — in the osteoid (unmineralized bone matrix) — where it appears to be involved in the initial mineralization process; silicon promotes osteoblast (bone-forming cell) differentiation and activity — increasing collagen type I synthesis, alkaline phosphatase activity, and osteocalcin expression; silicon inhibits osteoclast (bone-resorbing cell) formation and activity; silicon is required for the cross-linking of collagen and proteoglycans in the bone organic matrix — providing the structural framework for mineralization; and silicon may interact with the BMP-2 signaling pathway — enhancing bone morphogenetic protein activity (Reffitt et al., 2003, Bone).
Silicon and collagen synthesis
Silicon's most well-established biochemical role is in collagen biology: proyl hydroxylase — the enzyme that hydroxylates proline residues in procollagen (essential for collagen triple helix stability) — is silicon-sensitive; silicon promotes collagen synthesis in fibroblasts, osteoblasts, and chondrocytes in vitro; silicon deficiency in animal models produces dramatic connective tissue defects — including: abnormal skull and long bone development, reduced cartilage quality, thin skin with reduced collagen content, and aortic lesions (Carlisle, 1972, Science — the landmark study demonstrating silicon's essential role in chick bone development).
Silicon and skin aging
Silicon's role in skin health has attracted significant commercial and research interest: skin collagen content declines approximately 1% per year after age 20 — contributing to wrinkles, sagging, and reduced elasticity; silicon concentrations in skin decline with aging; and oral silicon supplementation has been studied for anti-aging skin effects: Barel et al. (2005, Archives of Dermatological Research) found that oral silicon supplementation (10 mg/day orthosilicic acid for 20 weeks) significantly improved skin roughness and decreased skin and hair brittleness in women with photodamaged skin.
Silicon and hair and nails
Silicon is one of the primary minerals in hair and nail keratin: hair silicon content correlates with hair strength and elasticity; nail brittleness has been associated with low silicon intake; and choline-stabilized orthosilicic acid supplementation improved hair tensile strength and thickness, and reduced nail brittleness in clinical studies (Wickett et al., 2007, Archives of Dermatological Research).
Silicon and cardiovascular health
Silicon concentrations are highest in the aorta — and decline progressively with aging and atherosclerosis development: silicon is involved in the biosynthesis of elastin and glycosaminoglycans in arterial walls; silicon-deficient animal models develop aortic lesions resembling early atherosclerosis; epidemiological studies have found inverse associations between dietary silicon intake and cardiovascular disease risk; and silicon in drinking water may contribute to the cardioprotective effects observed in populations consuming mineral-rich water (Jugdaohsingh, 2007, Journal of Nutrition, Health & Aging).
Dietary sources and absorption
The richest dietary sources of silicon include: beer (one of the highest bioavailable sources — silicon from barley and hops is dissolved as orthosilicic acid during brewing), whole grains (particularly oats, barley, and wheat — though silicon bioavailability from solid grains is lower than from liquids), bananas (unusually silicon-rich among fruits), green beans and other legumes, mineral water (silicon content varies widely by water source — some mineral waters provide >30 mg/L), and root vegetables (Jugdaohsingh et al., 2002, British Journal of Nutrition).
Dietary silicon intake in Western diets is approximately 20-50 mg/day — with men typically consuming more than women (partly due to higher beer consumption). No RDA has been established.
Silicon supplements
Several supplemental forms are available: orthosilicic acid (OSA — the most bioavailable form), choline-stabilized orthosilicic acid (ch-OSA — a stabilized liquid form with demonstrated bioavailability and clinical evidence), colloidal silica (lower bioavailability), and horsetail extract (Equisetum arvense — a traditional herbal silicon source, but with variable silicon content and uncertain bioavailability).
Silicon and Alzheimer's disease
An intriguing line of research connects silicon to aluminum toxicity and Alzheimer's disease: silicon (as silicic acid) binds aluminum in the GI tract and in the body — potentially reducing aluminum absorption and facilitating its excretion; populations consuming silicon-rich drinking water have been found to have lower Alzheimer's disease rates in some epidemiological studies; and Rondeau et al. (2009, American Journal of Clinical Nutrition) found that higher silica intake from drinking water was associated with a reduced risk of Alzheimer's disease in the French PAQUID cohort — an effect that was independent of aluminum exposure.
Silicon is an element whose biological importance is still being discovered — decades after the essentiality of iron, zinc, and calcium was established. Its concentration in connective tissues, its role in collagen biology, and its epidemiological associations with bone, skin, cardiovascular, and potentially cognitive health suggest that silicon may eventually be recognized as essential for human health. In the meantime, consuming whole grains, mineral water, and beer (in moderation) provides the dietary silicon that connective tissues require.
Silicon and joint health
Silicon's role in cartilage and connective tissue extends to joint health: glycosaminoglycans (GAGs) — hyaluronic acid, chondroitin sulfate, keratan sulfate — are the structural molecules of cartilage, and their synthesis involves silicon-sensitive enzymatic pathways; silicon concentrations in cartilage decrease with aging — and this decline parallels the loss of GAG content that characterizes age-related cartilage degeneration; animal studies show that silicon supplementation can increase GAG content in cartilage; and some researchers have proposed silicon supplementation as an adjunctive approach for osteoarthritis prevention — though controlled clinical trials are limited.
Silicon and immune function
Recent research has identified silicon's interactions with the immune system: silicon nanoparticles have been studied as vaccine adjuvants — their crystalline structure activates the NLRP3 inflammasome, potentially enhancing immune responses; silicon dioxide (silica) dust exposure causes silicosis — a chronic inflammatory lung disease — demonstrating that silicon can be a potent immune activator in inappropriate contexts; and dietary orthosilicic acid, in contrast, does not appear to cause inflammatory activation — suggesting that the form and route of silicon exposure determines whether immune effects are beneficial or harmful (Freudenberger et al., 2020, Nanomaterials).
Silicon and wound healing
Silicon compounds have shown wound healing properties: orthosilicic acid promotes fibroblast proliferation and collagen synthesis in vitro; silicon-containing biomaterials (bioactive glasses, calcium silicate cements) are used in tissue engineering and dental repair — releasing silicon ions that stimulate tissue regeneration; and silicon-doped hydroxyapatite bone grafts show enhanced osteogenesis compared to pure hydroxyapatite — demonstrating silicon's direct stimulatory effect on bone-forming cells.
Silicon and aging
Silicon intake and tissue silicon content decline progressively with age: blood silicon levels decrease approximately 30-40% between age 20 and 70; connective tissue silicon content decreases in parallel — contributing to: skin thinning and wrinkling (reduced collagen density and elasticity), arterial stiffening (reduced elastin integrity), bone loss (reduced matrix quality), and joint degeneration (reduced cartilage GAG content). Whether silicon supplementation can slow these age-related changes is an active research question — preliminary evidence is encouraging but large-scale clinical trials are needed.
Silicon bioavailability: the critical variable
Silicon bioavailability varies enormously by source: orthosilicic acid in water and beer — approximately 40-50% absorption (the most bioavailable natural source); solid foods (grains, vegetables) — approximately 2-20% absorption (silicon is often bound in insoluble polymeric silicates that resist digestion); silicon supplements — bioavailability depends on formulation (ch-OSA appears to be the most bioavailable supplemental form based on urinary excretion studies); and colloidal silica and siliceous earth supplements — low bioavailability despite high silicon content (Sripanyakorn et al., 2009, British Journal of Nutrition).
This bioavailability issue means that total silicon intake may be less important than the form of silicon consumed — a nuance that is critical for designing supplementation strategies and interpreting clinical trial results.
Silicon stands at the threshold of recognition — a mineral with consistent biological effects across bone, skin, cartilage, and cardiovascular tissues, supported by epidemiological associations and mechanistic plausibility, but awaiting the large-scale clinical trials and definitive biomarker studies that would cement its status as essential. Until then, consuming silicon-rich foods — whole grains, mineral water, and the occasional beer — provides the building blocks that connective tissues need to maintain their strength and resilience.
Silicon and kidney function
Silicon has important interactions with renal physiology: the kidney is the primary excretory organ for silicon — urinary silicon excretion reflects dietary intake and serves as a biomarker of silicon exposure; silicon (as silicic acid) binds aluminum in the GI tract — reducing aluminum absorption and potentially reducing the kidney's aluminum clearance burden; in chronic kidney disease, silicon excretion is impaired — leading to elevated serum silicon levels; and silicon dioxide nanoparticles are being developed as renal-targeted drug delivery systems — exploiting the kidney's natural silicon handling capacity.
Silicon in dental health
Silicon plays roles in dental tissues: silicon is found in tooth enamel and dentin; silicon-containing biomaterials (bioactive glasses, calcium silicate cements) are used in restorative dentistry — releasing silicon ions that promote remineralization and apatite formation; mineral trioxide aggregate (MTA) — a calcium silicate cement — is the gold standard for root canal perforation repair, apexification, and vital pulp therapy; and silicon-substituted hydroxyapatite toothpastes have been developed as remineralizing agents for caries prevention.
Silicon in sports and exercise
Silicon may play roles in exercise physiology and recovery: collagen is the primary structural protein of tendons, ligaments, and fascial tissues — all of which are stressed during exercise; silicon supplementation may support connective tissue repair after exercise-induced damage; athletes with higher silicon intake may have stronger connective tissues and reduced injury risk — though clinical evidence is limited; and silicon-rich mineral waters are popular among endurance athletes in some European countries — based on traditional beliefs about silicon's connective tissue benefits.
The silicon-aluminum-Alzheimer's hypothesis
Perhaps the most provocative silicon research involves Alzheimer's disease: aluminum is a known neurotoxin that accumulates in Alzheimer's disease brain tissue; silicon (as silicic acid) has a remarkable ability to bind aluminum — forming insoluble aluminosilicates and the soluble complex hydroxy-aluminosilicate (HAS); dietary silicon may reduce aluminum bioavailability and promote aluminum excretion; Exley et al. (2006, Journal of Alzheimer's Disease) found that silicon-rich mineral water consumption significantly increased urinary aluminum excretion — potentially reducing body aluminum burden; and a follow-up study found cognitive improvement in Alzheimer's patients who consumed silicon-rich mineral water for 12 weeks — though the study was small and uncontrolled (Davenward et al., 2013, Journal of Alzheimer's Disease).
While the aluminum hypothesis of Alzheimer's disease remains controversial, silicon's ability to reduce aluminum bioavailability is well-established and may have preventive value regardless of whether aluminum is a primary cause of AD.
Silicon is the mineral that builds the invisible infrastructure of the body — the collagen, elastin, and glycosaminoglycans that give tissues their strength, elasticity, and resilience. Its decline with age parallels the decline of these tissues, and its replenishment may support the structural integrity that keeps bodies functional and resilient throughout life.
Silicon in tissue engineering and biomaterials
Silicon-based biomaterials represent one of the most active areas of regenerative medicine: bioactive glasses (45S5 Bioglass® — the original, containing SiO₂, Na₂O, CaO, P₂O₅) bond to both bone and soft tissue — revolutionizing bone grafting, dental implants, and wound healing; mesoporous silica nanoparticles (MSNs) are being developed as drug delivery vehicles — their tunable pore size, high surface area, and biocompatibility allow controlled release of drugs, growth factors, and antibiotics directly to target tissues; silicon-doped calcium phosphate scaffolds for bone tissue engineering show enhanced osteoblast adhesion, proliferation, and differentiation compared to undoped scaffolds; and silicone (polydimethylsiloxane — PDMS) — while chemically distinct from nutritional silicon — is widely used in medical devices, breast implants, and microfluidic systems.
Silicon and water treatment
Silicon's interactions in drinking water are clinically relevant: silicon in natural mineral waters may contribute to cardiovascular protective effects observed in populations consuming mineral-rich water — the "French Paradox" may partly reflect high silicon intake from mineral water and wine; water treatment processes (aluminum-based flocculants) can reduce water silicon content — potentially reducing this dietary source; and silicon levels in drinking water vary enormously by geographic region — from <2 mg/L in some treated municipal supplies to >50 mg/L in some volcanic spring waters.
Silicon metabolism and genetics
Recent research has identified genetic factors influencing silicon metabolism: the sodium-dependent silicic acid transporter (SLC34/Slc34a2) — originally characterized as a phosphate transporter — also transports silicic acid; polymorphisms in silicon-related transport genes may influence individual silicon absorption and tissue distribution; and genome-wide association studies (GWAS) are beginning to identify loci associated with serum silicon levels — potentially explaining individual variation in connective tissue quality and aging patterns.
Silicon in different life stages
Silicon needs and metabolism change across the lifespan: during growth and development — silicon is actively incorporated into developing bone, cartilage, and connective tissues (children have higher silicon concentrations in connective tissues than elderly adults); during pregnancy — silicon is required for fetal connective tissue development, though specific pregnancy recommendations have not been established; during menopause — the decline in estrogen may affect silicon metabolism (estrogen appears to enhance silicon absorption and retention — potentially explaining why the Framingham silicon-BMD association was strongest in premenopausal women); and during aging — progressive decline in tissue silicon content parallels connective tissue deterioration.
Silicon and breast implant controversy
While chemically distinct from nutritional silicon (orthosilicic acid), silicone (polydimethylsiloxane) used in breast implants has generated controversy that sometimes creates confusion about silicon itself: silicone breast implants can rupture, releasing silicone gel — causing local inflammatory reactions; silicone-related immune dysfunction syndrome (proposed but contested) remains controversial; and importantly, there is no evidence that dietary silicon at normal levels poses any health risk — the concerns about silicone implants are specific to the synthetic polymer, not to elemental silicon or dietary orthosilicic acid.
The case for silicon essentiality
The accumulating evidence for silicon's biological importance includes: consistent epidemiological associations with bone and connective tissue health, demonstrated mechanisms in collagen synthesis, bone mineralization, and elastic tissue formation, the dramatic connective tissue defects observed in silicon-depleted animal models (Carlisle 1972, Science), the progressive decline in tissue silicon content that parallels age-related connective tissue deterioration, and the clinical improvement in skin, hair, and nail quality observed in supplementation studies. While no silicon-specific enzyme has been identified — and no silicon-deficiency disease has been formally characterized in humans — the weight of evidence suggests that silicon contributes importantly to structural biology in ways that may not require classical enzymatic mechanisms.
Silicon is the mineral of structure — the invisible architectural support that gives tissues their strength, flexibility, and resilience. Understanding it is understanding the molecular scaffolding of the human body.
Silicon is the invisible architect of the body's connective tissue — the mineral most people have never heard of, yet which every collagen fiber, every elastin network, and every glycosaminoglycan chain depends upon for its formation and integrity.