Sulfites in Food

Why They're Used, Risks They Can Pose, and Common Names

The bread aisle of an Iowa grocery store.
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Most of the packaged foods we eat need some type of food additives to keep the foods from spoiling or to improve the flavor or appearance. Sulfites are sulfur-based food additives that enhance flavor and preserve freshness. In general, when sulfites are added to foods and drinks, they are safe for most people and come without any health risks. For a small segment of the population, however, there is a risk of sulfite sensitivity or even an allergy to sulfites.

Uses

Sulfites are found in a variety of drinks, baked goods, sauces, dried fruit, snacks, and many other foods. Sulfites are useful as food preservatives because they slow down bacterial growth. They also improve the quality and texture of bread dough ​and prevent oxidation or browning of sliced vegetables and fruit. Sulfites also help keep black spots from developing on shrimp and lobster.

Possible Risks

Most people consume sulfites without issue. The United States Food and Drug Administration (FDA) estimates about 1 percent of the American population are sensitive to sulfites. The FDA also estimates 5 percent of people who have asthma are allergic to sulfites.

Experts are not yet sure how much sulfite is enough to cause a reaction or even what mechanisms cause one to occur. Symptoms of a reaction can include hives, diarrhea, nausea, shortness of breath, or even fatal anaphylactic shock. The reactions and allergy symptoms may start after eating foods that contain sulfites or possibly from simply breathing vapors that emanate from those foods.

Sulfite sensitivities may start at any time in a person's life, and there are no treatments to block sulfite allergies. Severe reactions may require the use of epinephrine, allergy medications, or asthma inhalers to reduce the symptoms.

The risk of having reactions to sulfites in food seems to be higher for people who have the following conditions:

  • Sensitivity to sulfur dioxide: Inhaling sulfur dioxide can act as an irritant that causes a reflex contraction of the airways. For people with particular sensitivity to it, the sulfur dioxide gas given off during the swallowing process of drinking beer or wines containing sulfites can case those same reflex contractions.
  • A deficiency in sulfite oxidase: Some people with asthma react to sulfites because they have a deficiency of the enzyme that breaks down sulfur dioxide. Without the enzyme, sulfites can be fatal as they can trigger severe asthma attacks.
  • Positive allergy tests to sulfites: Some people (but not many) have positive skin allergy tests to sulfites, indicating true (IgE-mediated) allergy.

Food Labeling

Because sulfites can be life-threatening for those people who have sulfite sensitivity, the FDA banned their use on foods that are typically eaten raw (such as fresh fruits and vegetables typically found at salad bars). Sulfites are often used in processed foods and must be noted on the food label of all packaged foods.

Sulfites can be naturally occurring in certain foods, but anything at levels at or above 10 parts per million (ppm) must be listed on product labels. The same goes for whenever they’re used as a preservative.

Other Common Names

On food labels, sulfites are not always listed as sulfites. This means that you have to be aware of other common terms used for them:

  • Sulfur dioxide (which is not a sulfite, but a chemical oxide that is closely related)
  • Potassium metabisulfite
  • Potassium bisulfate
  • Sodium bisulfate
  • Sodium metabisulfite
  • Sodium sulfite

Sulfite-Containing Foods

Sulfites are found in dried fruits, molasses, sauerkraut and pickled foods, pre-made gravies and sauces, canned vegetables, condiments, frozen shrimp, dehydrated potatoes, potato chips, jams, and trail mix. Sulfites also occur naturally in some foods, such as beer, wine, and fruit and vegetable juices. Fresh fruits and vegetables that are meant to be eaten raw are not allowed to contain any sulfites.

A Word From Verywell

If you think you may have a sulfite sensitivity, please see your healthcare provider. He or she can help determine if you need to avoid sulfites or, if not, what else may be at the root of the reactions you're experiencing.

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