Magnesium silicate and trisilicate

Magnesium silicate and trisilicate are inorganic minerals derived from magnesium oxide and silicon dioxide. In food applications they serve as anti-caking agents, absorbing moisture and preventing the formation of lumps in powdered products. They are used in chewing gum (where they act as a release agent), spice blends, powdered seasonings, and certain tableted food supplements. The trisilicate form has a higher silicon content and is particularly effective at moisture absorption.

JECFA classified the anti-caking use of these compounds as "not specified," meaning that the available toxicological evidence did not indicate a need to set a numerical ADI at levels consistent with their technical function in food. They are poorly soluble and not meaningfully absorbed in the gastrointestinal tract, which supports this benign assessment. Long histories of safe pharmaceutical use — magnesium trisilicate has been used as an antacid for many decades — also contribute to confidence in their safety profile.

Magnesium silicate and trisilicate are approved across the EU and in many other jurisdictions for specific food applications at regulated maximum levels. Their presence in foods is not typically visible or detectable by taste or texture; they are functional ingredients that work behind the scenes to maintain quality. Consumers who see E553a on a label can expect it to be present in a powdered or granulated product where free-flow and moisture control are technically important. No significant safety concerns have been identified at typical dietary intake levels.