Precipitated silica, or silica, is known in nature as sand or quartz. It occurs naturally in the earth’s crust, and silicates are present in water, animals and plants. Silicates are also consumed as part of the natural human diet.
In the pharmaceutical industry, silica (synthetic form of silicon dioxide) has many uses in tablet-making, including as an anti-caking agent, adsorbent, disintegrant, or glidant to allow powder to flow freely when tablets are processed. These compounds appear to be biologically inert.