Silicon oxide is a type of silica, and its chemical name is SiO2. It is composed of the element silicon bound with 2 oxygen molecules. Silica is the primary chemical compound found in sand and rocks, and makes up nearly 90 percent of the total Earth's mass. Silicon dioxide is inert, which means it will not interfere with any active ingredients in supplements or drugs. The type of silicon regularly used in food and supplements is synthetic amorphous silicon. Silicon dioxide and SAS are chemically identical.

Silicon oxide (SiO2), 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, silicon dioxide (also known as colloidal 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. Silicon dioxide is generally recognized as safe by the FDA.