Digestoa
Additive · Anti-caking

Silicon dioxide (E551)

Silicon dioxide (E551) is an anti-caking that Digestoa rates as low concern — it's considered safe at the levels used in food.

Digestoa riskLow risk
TypeAnti-caking
Found inpowdered foods, grated cheese, spices and table salt
ConcernsNanoparticle concerns (emerging research)

What is Silicon dioxide?

Silicon dioxide (E551) is an anti-caking — used to stop powders clumping.

Is Silicon dioxide bad for you?

Silicon dioxide is permitted in food and Digestoa rates it as low concern. There's no strong evidence it causes harm at the levels typically used in food.

What foods contain Silicon dioxide?

Powdered foods, grated cheese, spices and table salt.

Digestoa's take

You don't need to avoid Silicon dioxide. It's one of the more benign things on an ingredients list — worth knowing, not worth worrying about.

Safer swaps

Choose less-processed products with short, recognisable ingredient lists.

Frequently asked questions

Is E551 the same as Silicon dioxide?
Yes — E551 is the international additive (E-number) code for Silicon dioxide.
Is Silicon dioxide bad for you?
Digestoa rates Silicon dioxide (E551) as low concern. It's permitted in food and considered safe at normal dietary levels.
What are the side effects of Silicon dioxide?
Reported concerns include: Nanoparticle concerns (emerging research).
What foods contain Silicon dioxide?
Powdered foods, grated cheese, spices and table salt.
How can I avoid Silicon dioxide?
Check the ingredients list for "Silicon dioxide" or "E551", or scan the product with Digestoa to see if it's present before you buy.

Risk ratings reflect Digestoa's editorial assessment synthesising EFSA/IARC opinions and peer-reviewed research. Informational only — not medical advice.