Sulfur dioxide is used as a preservative found in many foods, including shrimp, pickled foods and, in particular, dried fruit. For people who are sensitive to the preservative or have asthma, the health risks of sulfur dioxide in dried fruit can range from mild to severe.
Sulfur dioxide helps keeps food fresh and is considered safe for most people. However, people who have asthma are more at risk for having a reaction to this preservative.
What Does Sulfur Dioxide Do?
Many foods contain preservatives to maintain freshness, and dried fruit is no exception. The USDA states that sulfur dioxide is used on foods, such as dried fruits, to prevent rotting and browning, as well as to maintain their color and appearance.
The use of sulfur dioxide started to become widely used on foods in the 1970s. In 1986, the FDA banned sulfites — which contain sulfur dioxide — from being used in fresh fruits and vegetables after it caused health issues in people with asthma. Sulfur dioxide, however, is still used in many foods including dried fruits, processed meats like hot dogs and even some baked goods.
Read more: 10 Facts about Food Allergies
Sulfur Dioxide Side Effects
If you are a healthy person, the sulfur dioxide in dried fruits will most likely not cause any reaction. The USDA reports that only 1 percent or less of the population will show some sort of sensitivity to sulfur dioxide, but notes that there is a strong association between asthma attacks and this preservative.
Sulfur dioxide side effects to be aware of include tightness in your chest and throat, wheezing and coughing, reports an article in the March 2017 issue of the Journal of Asthma and Allergy. For some people, especially those with asthma, the side effects can turn into a life-threatening anaphylaxis reaction.
Nonrespiratory effects for some individuals include hives, headaches and itchy skin. Additionally, a study published in the October 2017 issue of the journal Public Library of Science states that this preservative stops the growth of beneficial gut bacteria, which may cause stomach discomfort or diarrhea.
Read more: The Most Common Food Preservatives
Testing for Sulfur Dioxide Allergies
If you don't have asthma, the probability that you have a sensitivity to sulfur dioxide is low. If you have asthma or suspect that this preservative is giving you a reaction, the Cleveland Clinic suggests seeing a doctor to test for a sulfur dioxide allergy. Your doctor will give you a small dose of sulfite and carefully monitor you for a reaction for 20 to 30 minutes. The dose of sulfite is slowly increased as your reaction and lung function is monitored.
This test can take up to 2.5 hours to complete. If you have a reaction, you will be given a bronchodilator medication to quickly relieve the symptoms.
The Cleveland Clinic states that if you do have asthma, the chance that you will have a reaction to sulfur dioxide or sulfites is between 1 and 20 and 1 and 100. Because the symptoms can range from moderate to severe, if you have asthma, it is important to be tested so you know how this preservative will affect you.
Dried Fruit Without Sulfur Dioxide
Dried fruit is a healthy food choice, as it is full of fiber and antioxidants. Luckily, it doesn't have to be completely eliminated from your diet if you have a sulfur dioxide allergy. To find dried fruit without sulfur dioxide, look for organic dried fruits. They won't have quite as long of a shelf life as regular dried fruit, but the organic version is preservative-free and can be frozen to make it last longer.
An article featured in the June 2016 issues of the journal Toxicology Reports recommends avoiding sulfur dioxide in your diet by carefully reading labels when buying processed food, especially foods that have a long expiration date or long shelf life. Sulfur dioxide can be listed as other terms, so look for sulfites, potassium bisulfite or metabisulfites.
Read more: Health Benefits of Dried Fruit
If you love dried fruits but want to avoid sulfur dioxide, cook your own preservative-free batch. Make dried fruits yourself by cooking fruit slices at low heat for several hours until they reach that perfect chewy texture.
- U.S. Department of Agriculture: "Sulfur Dioxide Handling"
- University of Florida: "Sulfites: Separating Fact From Fiction"
- Journal of Asthma and Allergy: "Environmental Triggers and Avoidance in the Management of Asthma"
- Public Library of Science: "Sulfites Inhibit the Growth of Beneficial Gut Bacteria"
- Harvard Health Publishing: "Is Eating Dried Fruit Healthy?"
- Toxicology Reports: "Food Safety Risk Assessment for Sulfites in the Taiwanese Population"
- Cleveland Clinic: "Sulfite Sensitivity"
- University of Nebraska-Lincoln: Food Allergy Research and Resource Program: "Sulfites - USA"