Silica (Silicon Dioxide)

Updated June 29, 2026

Silicon is the second most abundant element in the Earth’s crust, and in biological systems it exists primarily as silicon dioxide (silica) or orthosilicic acid — the soluble, bioavailable form that circulates in human blood. Silicon was long considered biologically inert, but research from the 1970s onward established it as an essential trace element for connective tissue synthesis. It is required for the cross-linking of collagen and elastin fibres, the mineralisation of bone matrix, and the integrity of articular cartilage. Deficiency in animal studies produces dramatic defects in bone and connective tissue development.

The connective tissue and beauty applications are the most commercially prominent. Silicon stimulates collagen type I synthesis in fibroblasts and is found in high concentrations in skin, hair follicles, nails, aorta, and bone. Multiple clinical trials with bioavailable orthosilicic acid (stabilised in choline, sold as ch-OSA) demonstrate significant improvements in hair tensile strength, nail brittleness, and skin elasticity versus placebo after 20 weeks of supplementation. These are not trivial cosmetic effects — the structural improvements reflect real changes in collagen architecture. Epidemiological data links higher dietary silicon intake with greater bone mineral density, particularly in pre-menopausal women.

Diatomaceous earth (DE) is a naturally occurring silica powder made from fossilised remains of diatoms — microalgae with silica cell walls. Food-grade DE is widely used as a gut cleanser and gentle binder: its sharp microscopic edges are proposed to physically damage parasites and sweep gut debris, while its silica content provides the biological effects above. Evidence for the antiparasitic claim in humans is anecdotal; evidence for the mineral benefit is more credible. DE is also used as a flow agent and anti-caking ingredient in many supplements.

Bioavailability varies dramatically by form. Orthosilicic acid is highly bioavailable (around 64% absorption from ch-OSA supplements). Silicon dioxide powder (as found in most capsule fillers) and diatomaceous earth are poorly bioavailable. For therapeutic effect — particularly for hair, skin, and connective tissue — bioavailable forms are meaningfully superior. Standard doses for ch-OSA are 10 mg elemental silicon daily; for DE as a binder, 1 to 2 teaspoons in water taken away from food. Like other binders, DE should be timed away from medications. Silica supplements in food-grade forms are considered very safe. This is general information, not medical advice.