What Are Sulfites?

sulfite explanation

What are Sulfites (Sulphites) is becoming a common question because they are found in many food products as well as cosmetics people consume or use everyday.

Some people can have mild to severe reactions to these compounds, so it’s important to understand what sulfites are and in what forms they exist in foods and products.

Basic Chemistry

Basically sulfites (sulphites) refer to compounds that contain a sulfite ion.  This means they are made up of a sulfur atom and three oxygen atoms.

They are usually combined with sodium or potassium before they can have industrial applications.

What Are Sulfites Also Called?

Some products like wine will say “contains sulfites” but for other products label reading is necessary.

Here are ingredients to look for as they are the different names for sulfite containing chemicals. Also in some countries numbers are used and not names, so they are included as well.

  • Sulphite ammonia caramel E150d
  • Caustic sulphite caramel E150b
  • Sodium bisulphite (sodium hydrogen sulphite) E222
  • Sodium sulphite E221
  • Potassium metabisulphite E224
  • Sodium metabisulphite E223
  • Potassium sulphite E225
  • Calcium hydrogen sulphite E227
  • Calcium sulphite E226
  • Potassium hydrogen sulphite E228
  • Sulfur Dioxide (not a true sulfite, but chemically very close)

Why Are They Used?

sulfite-usesSulfites are generally used as a preservative. They keep harmful bacterial or fungal organisms from growing in food products.

They also act as antioxidants in dried fruit and wine to prevent the product from turning to a brownish color.

In wine they prevent the wine from turning to vinegar.

They extend the shelf-life of many products and are widely used in agricultural ways.

Sometimes trace amounts can be found in products because of the indirect ways sulfites are used. Most countries do not require labeling of trace amounts of the compound.

Many people don’t realize that common elements found in foods and other accessories can be downright harmful to a human. Sulfites, for example, are found all over the place, exposing people to dangers they’re not even aware of.

People very sensitive to the chemicals can have reactions even if sulfites are not on the item’s label.

It’s important to understand all of the ways sulfites can be used and the products that are most contaminated with the compounds to be safe.


  • FMI.org
  • WOW
  • Sapers, G. M. (1993). Browning of foods: control by sulfites, antioxidants, and other means. Food Technology, 47(10), 75-84.
  • Taylor, S. L., Higley, N. A., & Bush, R. K. (1986). Sulfites in foods: uses, analytical methods, residues, fate, exposure assessment, metabolism, toxicity, and hypersensitivity. Advances in Food Research, 30, 1-76. link
  • Joslyn, M. A., & Braverman, J. B. S. (1954). The chemistry and technology of the pretreatment and preservation of fruit and vegetable products with sulfur dioxide and sulfites. Advances in food research, 5, 97-160. link