Is Silicon Dioxide Vegan? (a.k.a. Silica, E551, Kieselsol, etc)

I remember when I first went vegan 14 years ago, it was a little overwhelming to see all the chemical names in ingredient lists. I had no idea what something like “silicon dioxide” could be. But over time, I have researched pretty much all of these chemical-sounding ingredients.

So, is silicon dioxide vegan? Silicon dioxide (silica) is vegan since it is just a mineral found in sand, rocks, and the Earth’s crust. It is not derived from an animal. There are many forms of silicon dioxide—silica gel, kieselsol, diatomaceous earth, and more. All are generally vegan.

Although all forms of silica are generally vegan, there are some usages of them that are arguably not vegan since they involve other animal products or harming animals. Read on to learn all the details, or skip to the heading that fits your concern!

What Is Silicon Dioxide?

Silicon dioxide is a common mineral in sand, rocks, and the earth’s crust. Chemically, it’s a molecule containing one atom of silicon and two of oxygen (SiO2). Silicon dioxide is also called “silica.” In this post, I use the terms interchangeably.

Silicon dioxide is commonly found in many fruits and vegetables naturally. It’s also in quartz. As a food additive, it’s commonly used as an anti-caking agent. It prevents things from clumping up in ways they’re not supposed to.

Luckily, silicon dioxide appears to be safe for consumption. The only caveats I found are that:

  • (1) In Europe, there has been some concern expressed over the exact size of the particles. (source)
  • (2) The FDA has put an upper limit on consumption (2% of food weight) because it is unknown how large doses would affect people. (source)

Why Silicon Dioxide Is Vegan

In order to be vegan, food ingredients should not be animal-derived or involving animals in their production. Since the production of silica does not involve animals or animal by-products, it is vegan.

The Many Names/Forms of Silicon Dioxide

I used the basic mineral name “silicon dioxide” for the title of this post, but there are many forms of silica that go under different names.

The E-number for silicon dioxide is E551, so sometimes you may see that listed. Let’s cover some of the other common names/types and whether they’re vegan!

Silica Gel

Silica gel is used for many purposes. You may have seen it in a small “do not eat” paper envelope inside of a pill bottle or other packaged food. In that case, it’s being used as a desiccant. It’s there to absorb any moisture in the package.

Here are some other common uses of silica gel:

  • In chemistry labs as a “stationary phase” in chromatography.
  • In cat litter, often in combination with clay or other substances.
  • In domestic water filters that remove some minerals from the water.
  • As a food additive, sometimes under the name hydrated silica or silica aerogel. It’s used as an anticaking agent, emulsifier, and more.

It’s a little strange to me that silica gel packages are often labeled with “do not eat,” but the same basic ingredient is used as a food additive! I’m guessing the quantities used as a food additive are just much lower or sometimes the desiccants may include extra ingredients.

Is Silica Gel Vegan?

Silica gel is vegan. It is composed mainly of silicon dioxide, a mineral from the natural environment, sometimes together with water or other chemicals. Silica gel can be used as a vegetarian replacement for gelatin in certain cases.

Silica Dimethyl Silylate

Silica dimethyl silylate is an ingredient often used in cosmetics or personal care products. It’s a type of “siloxane polymer,” which means that the backbone of the molecule is made up of alternating silicon and oxygen atoms.

Specifically, it’s used as an anticaking agent, bulking agent, slip modifier, or viscosity increasing agent. (source)

Is Silica Dimethyl Silylate Vegan?

Silica dimethyl silylate appears to be vegan. It’s a type of hydrophobic fumed silica, which is made by heating up silicone tetrachloride or quartz sand. The MakingCosmetics brand of silica dimethyl silylate is clearly labeled as vegan.


Kieselsol is a form of silica used as a fining agent in wine production. If you don’t know what fining is, let me explain.

Fining agents are added to wine to adsorb impurities and stuff like tannins that the winemaker wants to remove. Once the fining agent has clumped together with the impurities, they’re then filtered or centrifuged out together.

You may have heard that not all wine is vegan. Well, the fining agents are usually the reason.

Many fining agents are animal-derived, including gelatin, egg whites, isinglass (fish gelatin), casein (milk protein), and chitin (from the exoskeleton of arthropod animals). The fining agent is removed from the final product, but this is still not ideal from a vegan perspective.

Luckily, there are also vegan fining agents, including bentonite (made from volcano ash) and, yes, kieselsol (made from silicon dioxide)!

Is Kieselsol Vegan?

Kieselsol itself is vegan, as it is made from silica. However, it is often used in combination with other fining agents such as chitosan, which is usually derived from shrimp shells. Be cautious about these other fining agents if you are looking for a fully vegan winemaking process.

By the way, there is a vegan version of chitosan. It’s made from a fungus that also produced chitin—so animals don’t have to be involved at all!

Diatomaceous Earth

The faces in Mount Rushmore were carved away using dynamite, a product of nitroglycerin mixed with diatomaceous earth.

Diatomaceous earth (DE) is a type of sedimentary rock made of 90% silica. It actually comes from the fossils of a protist organism called diatoms. The cell walls of diatoms contain the silicon that makes up DE.

If you’re not familiar with protists, most of them are single-celled organisms. They’re microscopic—but not quite the same as bacteria or fungi like molds. They’re technically any eukaryotic organism that isn’t a plant, animal, or fungus. More info on protists here.

Anyway, diatomaceous earth is a soft, silica-based rock that easily crumbles into powder. It has a ton of uses:

  • Dynamite: It’s a combination of nitroglycerine and diatomaceous earth.
  • Insecticide: DE is used to adsorb lipids from insect exoskeletons. This causes the insects to lose water and dehydrate. DE is also used to fend off slugs or other pests in gardening.
  • Filtration: DE is used to filter water, syrups, honey, or other substances.
  • Thermal insulation: DE is used in fire-resistant safes, and it has uses in cryogenics, too.
  • And more (including cat litter)!

Is Diatomaceous Earth Vegan?

Diatomaceous earth is generally considered vegan. It is the fossilized remains of single-celled protist organisms, and animals are not involved. The only non-vegan use of diatomaceous earth may be as an insecticide. Some vegans oppose traditional forms of pest control that intentionally kill insects.

Insects are animals, and their level of sentience is unknown. So vegan pest control is a matter of debate and depends on your beliefs. See my big master post on vegan ethics for more on that!

But again, in general… Are diatoms vegan? Diatoms are vegan since they are protists, not animals. They are a type of single-celled algae, not a sentient creature. Therefore, it is generally vegan to use diatoms or their fossilized remains (diatomaceous earth).

Two More Recommendations for Your Plant-Based Journey

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