How to Spot Sulfites on Food Labels

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 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 prevent 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 FDA also estimates 5% of people who are sensitive to sulfites have asthmatic reactions.

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, shortness of breath, or even fatal anaphylactic shock. The reactions and allergy symptoms may start minutes or hours after eating foods that contain sulfites.

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: Inhaled sulfur dioxide can act as an irritant that causes the airways to reflexively contract. When people consume food or drink containing sulfites, the chemicals in their digestive tract can combine with sulfites to form a tiny amount of sulfur dioxide. The amount is too small for most individuals to react to, but some people are sensitive enough to develop those same reflexive contractions.
• A deficiency in sulfite oxidase: Some people have a deficiency of the enzyme that breaks down sulfite. Without the enzyme, sulfites can build up to dangerous levels and 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.

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:

• Potassium metabisulfite
• Potassium bisulfite
• Sodium bisulfite
• Sodium metabisulfite
• Sodium sulfite

Sulfur dioxide is not a sulfite, but rather a closely related chemical compound. When sulfite-containing food is digested, the chemical reaction can sometimes create sulfur dioxide, which irritates our airways and can cause difficulty breathing.

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 fermented drinks, such as beer and wine. 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. They 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.