Silicon Dioxide (E 551)

Last reviewed October 19, 2026

In plain words: Silicon dioxide (E 551), also called silica, is an anticaking agent that keeps powdered foods such as salt, spices, powdered drink mixes and supplements free-flowing. This page is not the same as the separate silicon dioxide nanoparticles page, which covers research on nano-sized particles.

Also listed on labels as: Silicon dioxide, Silica, Synthetic amorphous silica, E551, INS 551

What do regulators say?

EU: EFSA re-evaluated silicon dioxide (E 551) as a food additive in 2018 (doi:10.2903/j.efsa.2018.5088, checked 2026-10-19).
US: listed as a food additive at 21 CFR 172.480, "Silicon dioxide" (eCFR, checked 2026-10-19).

Published research: what individual studies found

These are findings from individual published studies and food-safety agency opinions, credited to each paper. Each one is labeled by type of evidence. They do not change any verdict, evidence grade or score on this site.

Evidence type: Animal (NOD/DQ8 mice)

Our results suggest that chronic oral exposure to fg-SiO2 blocked oral tolerance induction to OVA, and worsened gluten-induced immunopathology in NOD/DQ8 mice. A mouse strain used to model gluten sensitivity.
Source: Lamas B et al., Environ Health Perspect, 2024 · doi:10.1289/ehp12758

For information only, not medical advice. Studies are cited to their authors' published papers; the researchers aren't affiliated with and don't endorse Let Me Scan That or any product. A study link doesn't mean an ingredient causes harm. Report an error

Related guides

Sources

EFSA ANS Panel, Re-evaluation of silicon dioxide (E 551), EFSA J, 2018. Link
eCFR, 21 CFR 172.480 Silicon dioxide. Link

This page is for general education. It is not medical advice and does not replace advice from your doctor, pediatrician, allergist or registered dietitian. Research changes; we review these pages when new evidence or rules come out. Last reviewed October 19, 2026.