11/05/2025
Sulfites are a group of chemicals found naturally in some foods and also used as a preservative additive to maintain color, extend shelf life, and prevent microbial growth in other products. For most people, they are safe to consume, but some individuals with asthma may be sensitive and experience allergy-like symptoms, ranging from mild to severe, which is why they are required to be declared on food labels in many countries.
What they are
Naturally occurring: Sulfites are a natural byproduct of fermentation and are found in foods like wine, beer, and some fermented or dried fruits.
Added as a preservative: They are added to a wide range of processed foods to preserve their quality, including some canned and frozen fruits and vegetables, baked goods, and fruit juices.
Other uses: They are also used in other products, such as in the production of some food packaging materials and as a component in some medications.
Health concerns
Sulfite sensitivity: Sulfites can cause allergic-like reactions in sensitive individuals, with a higher prevalence of sensitivity among people with asthma.
Symptoms: Reactions can include wheezing, shortness of breath, coughing, hives, and a stuffy or runny nose.
Anaphylaxis: In rare cases, a severe reaction called anaphylaxis can occur, which is a life-threatening condition.
How to identify and avoid
Read food labels: In many places, including Canada and the United States, the presence of sulfites as a food additive must be declared on the label.
Look for common names: Sulfites may be listed under various names, so it's important to check for terms like sodium bisulfite, potassium metabisulfite, or sulfur dioxide.
Be cautious when eating out: If you have a sulfite sensitivity, ask restaurant staff if sulfites are used in their food preparations.
Avoid fresh fruits and vegetables: The FDA banned the use of sulfites on fresh fruits and vegetables in 1986, though they are still found in processed versions.
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