E551 — Silicon dioxide
E551 (Silicon dioxide), a anti-caking agent, is rated "avoid": worth avoiding. An anti-caking agent in powders, salt, and supplements. EFSA flagged data gaps around nanoparticle content in 2018 and could not establish a safe intake for infants.
What is Silicon dioxide?
Sand-derived silica in fine powder form. Used to keep table salt, powdered sugar, spice mixes, drink mixes, and supplements free-flowing.
What does it do to the body?
Most passes straight through your gut. The open question is whether the food-grade form contains enough nanoparticles to enter cells. EFSA flagged in 2018 that the current EU specifications don't exclude nanoparticles and the long-term data is insufficient.
What regulators say
EFSA could not set a numerical acceptable daily intake in 2018, citing data gaps especially around nano-form characterisation. The European Commission later restricted nano-titanium dioxide on similar grounds. The FDA approves silica as GRAS at up to 2%.
Risk rating: Avoid
Known or suspected to cause harm: a substance EFSA or another regulator has flagged, or one restricted in some jurisdictions. Best kept out of a regular diet.
Source: EFSA — re-evaluation of silicon dioxide (2018) ↗