Silicon (Silica)

Silicon (Si) is a metalloid element that, in the form of silicon dioxide (SiO₂) or “silica,” is the most abundant mineral in the human body after calcium. In dietary supplements it is supplied as orthosilicic acid (OSA) or its stabilized forms, which are the biologically active species that support connective‑tissue integrity, bone health, and skin structure.

• Silicon dioxide (SiO₂) is a tetrahedral network solid; its monomeric form, orthosilicic acid, is H₄SiO₄ (IUPAC: siliconic acid).
• In aqueous solution, OSA exists as a neutral, non‑ionic species with a pKa of ~9.5, making it stable at physiological pH (7.4) when stabilized.
• The polymeric form (SiO₂·nH₂O) is insoluble; however, the monomeric OSA is water‑soluble and can form hydrogen‑bond networks with proteins.
• Molecular weight: 60.08 g mol⁻¹ (SiO₂) and 98.08 g mol⁻¹ (H₄SiO₄).
• It is a weak acid, and its bio‑availability is dictated by its monomeric state, which is preserved by complexation with magnesium, choline, or sodium ions in commercial preparations.

• Commercial silica supplements are derived from two main sources:
  • (1) Miller‑type extraction of high‑purity quartz (SiO₂) followed by hydrolysis and stabilization to produce orthosilicic acid
  • (2) Biogenic silica from diatomaceous earth (siliceous algae) or rice husk ash, both of which are high‑silica agricultural by‑products.
• The extraction process uses acidic or alkaline leaching, followed by purification (filtration, ion‑exchange) to remove heavy metals and trace contaminants.
• Quality‑control measures include ICP‑MS verification of <10 ppm heavy metals (lead, cadmium, arsenic) and confirmation of >90 % monomeric OSA via NMR spectroscopy.
• Certified “Food‑Grade” or “Pharmaceutical‑Grade” labels indicate compliance with USP or EFSA standards for purity and bio‑availability.