What are Sulfites and Why are They Used?
Sulfites are sulfur-based compounds used as preservatives in food and beverages to prevent spoilage and maintain freshness. They act as antimicrobials and antioxidants, preventing discoloration (browning) and inhibiting the growth of bacteria. Sulfites can also occur naturally during fermentation, like in wine and beer.
Common sulfiting agents include sulfur dioxide, sodium bisulfite, and potassium metabisulfite. These compounds are found in a variety of products, both naturally and as additives. Their use is regulated to ensure food safety for the general population. While harmless for most, they can trigger adverse reactions in sensitive individuals.
Sulfite Sensitivity vs. Allergy
Most reactions to sulfites are considered a sensitivity or intolerance, not a true IgE-mediated allergy. A true allergic reaction involves the immune system producing antibodies (IgE) to fight a perceived threat, while a sensitivity or intolerance does not. The mechanisms behind sulfite sensitivity are not completely understood but may involve inhaling sulfur dioxide released from the food, a deficiency in the enzyme that breaks down sulfites (sulfite oxidase), or the release of histamine.
Symptoms of Sulfite Sensitivity
Symptoms of sulfite sensitivity can appear quickly after consuming a food or beverage with sulfites. The severity and type of symptoms vary. Those with asthma are at a higher risk.
Commonly reported symptoms include:
- Respiratory: Wheezing, chest tightness, coughing, and shortness of breath. This is common, especially for asthmatics. In severe cases, it can trigger an asthma attack.
- Skin: Hives (urticaria), flushing, redness, and itchy skin.
- Gastrointestinal: Stomach cramps, abdominal pain, diarrhea, and nausea.
- Cardiovascular: Low blood pressure, dizziness, and a rapid heartbeat.
- Other: Headaches and swelling of the face, lips, or tongue.
In rare but severe cases, sulfite sensitivity can lead to anaphylaxis, a life-threatening allergic reaction requiring immediate medical attention.
Sulfites and Headaches: Dispelling the Myth
Many attribute headaches after drinking wine to sulfites, but research suggests this is a misconception. Red wine often gets blamed, but typically contains lower sulfite levels than white wine, as tannins act as natural preservatives. Other compounds in wine, like histamines, tannins, and alcohol, are more likely culprits. If you get headaches from dried fruit but not wine, sulfites may not be the issue.
Foods and Drinks High in Sulfites
To manage sulfite sensitivity, awareness of high-sulfite foods and drinks is essential. Sulfites must be listed on food labels in the United States if they are present at 10 parts per million (ppm) or higher.
Common High-Sulfite Items:
- Wine and Beer: Sulfites are a natural byproduct of fermentation and are often added.
- Dried Fruits: Especially light-colored varieties like apricots and golden raisins.
- Processed Potatoes: Dried potatoes, instant mashed potatoes, and frozen french fries.
- Seafood: Shrimp and other processed seafood are often treated with sulfites to prevent black spot discoloration.
- Condiments: Horseradish, pickles, and some salad dressings.
- Certain Baked Goods: Some cookies, crackers, and pie crusts.
- Processed Meats: Deli meats, hot dogs, and sausages.
- Fruit and Vegetable Juices: Especially bottled concentrates.
Natural vs. Added Sulfites
| Feature | Natural Sulfites | Added Sulfites |
|---|---|---|
| Source | Produced naturally by yeast during fermentation in foods like wine, beer, and some fermented products. | Deliberately added to foods and drinks as a preservative, antioxidant, and bleaching agent. |
| Purpose | Naturally occurring chemical compound within fermented products. | Prevents bacterial growth, inhibits browning, and preserves color and freshness. |
| Regulation | All products containing more than 10 ppm of total sulfites, whether natural or added, must declare 'contains sulfites'. | Must be explicitly labeled when added in sufficient quantities. |
| Example Foods | All wines (to some extent), aged cheeses. | Dried fruits, processed potatoes, deli meats, many condiments. |
Reducing Sulfite Intake
Avoiding sulfites is the primary management strategy for diagnosed sensitivity. A registered dietitian can help create a diet plan that minimizes exposure.
- Read Labels Carefully: Check the ingredient list for terms like sulfur dioxide, potassium bisulfite, and sodium metabisulfite.
- Choose Fresh Foods: Opt for fresh, unprocessed fruits and vegetables over canned, frozen, or dried versions. In the U.S., sulfites are banned on fresh produce at salad bars.
- Cook at Home: Preparing meals from fresh ingredients gives complete control over ingredients, important for gravies, sauces, and dressings.
- Choose Low-Sulfite Wines: Some winemakers, including those producing organic wines, add low or no additional sulfites.
- Consult a Healthcare Provider: If you experience symptoms, talk to a doctor. They can determine the cause and provide an action plan, which might include carrying an antihistamine or epinephrine injector if your reactions are severe. For more on managing food sensitivities, see the Australasian Society of Clinical Immunology and Allergy (ASCIA).
Conclusion
While safe for most, eating sulfites can cause unpleasant symptoms for those with sensitivity, especially asthmatics. Understanding which foods and drinks contain sulfites and reading labels is key. Dispelling myths, like the connection between sulfites and wine headaches, is also crucial. By taking proactive steps and consulting with healthcare professionals, individuals can manage their diet and health effectively.
