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Last reviewed July 16, 2026

Silicon dioxide (silica, E551)

Silicon dioxide is sand, essentially, added to keep powders from clumping. There is nothing animal about a mineral.

Where it hides

  • Powdered and granulated foods
  • Spice blends and salt
  • Supplements and tablets
  • Coffee whiteners

What it is

Silicon dioxide is one of the most common minerals on Earth, and the food-grade version is a fine powder that stops other powders clumping.

Primary source 01 / 01

Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO2, and is commonly found in nature as quartz.

Wikipedia encyclopedia entry Silicon dioxide, 2025

A mineral, so vegan

As an anti-caking agent in spice blends, powdered supplements and coffee whiteners, silicon dioxide is doing a purely physical job, and because it is a mineral it carries no animal origin. It is vegan.

  • Maltodextrin Maltodextrin is processed plant starch, a bland filler and bulking agent. Corn, wheat or tapioca in, white powder out, no animal step.
  • Calcium carbonate (chalk, E170) Calcium carbonate is chalk, essentially, quarried from rock to firm, whiten and fortify. It is a mineral, so it sits on the vegan side, with a rare shell-derived footnote.
  • Bone phosphate (E542) Bone phosphate, additive E542, is exactly what it sounds like. It is ground animal bone, used as an anti-caking agent and a mineral source.

Frequently asked

Is E551 vegan?

Yes. E551 is silicon dioxide, a mineral, so it is vegan.

What does silicon dioxide do in food?

It is an anti-caking agent, keeping powders and granulated products free-flowing so they do not clump. It is a mineral and vegan.

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