What is Sulfur Dioxide and Why is it in Our Food?
Sulfur dioxide ($SO_2$) is a colorless gas with a pungent odor that has been used for centuries as a food preservative and antioxidant. In modern food production, it is typically added in the form of sulfite salts (E220-E228). Its primary functions are to inhibit the growth of spoilage-causing microbes like bacteria, yeast, and molds, and to prevent the oxidation of food. This antioxidant property is especially important for preventing the browning of dried fruits like apricots and the degradation of flavor and color in wines.
The Health Effects of Sulfur Dioxide Preservative
The health implications of consuming sulfur dioxide differ significantly between the general population and individuals with specific sensitivities. For the average, healthy person, the small, regulated quantities found in food are processed and excreted by the body without issue. For others, the effects can be more serious.
Impact on the General Population
Most healthy individuals can consume food preserved with sulfur dioxide without experiencing any adverse effects. Its long history of use and the fact that international food safety authorities, including the Joint Food and Agriculture Organization / World Health Organization Expert Committee on Food Additives (JECFA), have evaluated its safety, supports this. For these individuals, the presence of sulfur dioxide in food is not harmful.
The Risks for Asthmatics and Sensitive Individuals
The primary health concern regarding sulfur dioxide and its sulfite derivatives is for those with asthma or a documented sulfite sensitivity. Studies have shown that a significant percentage of asthmatics have some form of sulfite sensitivity.
Common reactions in sensitive individuals can include:
- Respiratory issues: Wheezing, shortness of breath, coughing, and chest tightness, sometimes severe enough to require emergency medical attention. Inhaled $SO_2$ gas is particularly irritating to the respiratory tract.
- Allergy-like symptoms: Hives, itching, and a stuffy or runny nose.
- Gastrointestinal discomfort: Stomach pain, nausea, and diarrhea can occur.
- Anaphylaxis: In very rare and severe cases, a life-threatening anaphylactic reaction can be triggered.
The FDA banned the use of sulfites on fresh fruits and vegetables in 1986 following reports of severe reactions in asthmatics. However, the preservative is still widely permitted in other food categories.
Comparison of Dried Fruit Options: Sulfured vs. Unsulfured
Dried fruit is one of the most common products to contain sulfur dioxide. Here is a comparison of sulfured versus unsulfured varieties:
| Feature | Sulfured Dried Fruit | Unsulfured Dried Fruit |
|---|---|---|
| Appearance | Bright, vibrant color (e.g., orange apricots) due to antioxidant properties. | Darker, often brown or grayish color, as natural oxidation occurs. |
| Shelf Life | Extended shelf life due to microbial and antioxidant protection. | Shorter shelf life; requires refrigeration or freezing to maintain freshness. |
| Taste | Often has a more predictable, consistent flavor profile. | Flavor can be more concentrated and may have slight variations. |
| Health Concerns | Risk of allergic reactions for asthmatics and sulfite-sensitive people. | No risk of sulfite-related reactions, making it a safer choice for sensitive individuals. |
| Availability | Widely available in conventional grocery stores. | Available primarily in organic food sections, health food stores, or online. |
How to Avoid Sulfur Dioxide in Your Diet
For those who are sensitive or wish to minimize their intake, avoiding sulfur dioxide is manageable by becoming a careful label reader. The presence of sulfites above 10 parts per million (ppm) must be declared on food labels. Look for words like “sulfites,” “sulfur dioxide,” or specific numbers like “E220-E228” in the ingredient list.
Foods commonly containing added sulfites include:
- Dried fruits and vegetables: Including apricots, raisins, apples, and potatoes.
- Wines and Ciders: Both red and white wines, which contain sulfites naturally but often have more added.
- Processed meats: Hot dogs, sausages, and some luncheon meats may contain sulfites.
- Fruit juices and concentrates: Certain juices and packaged fruit salads use sulfites to prevent browning.
- Condiments and Jams: Some syrups, molasses, and other packaged goods.
For a truly sulfite-free option, especially with dried fruits, look for products certified organic, as they are typically produced without synthetic preservatives.
Inhaled vs. Ingested Sulfur Dioxide: A Key Distinction
It is crucial to differentiate between the health effects of inhaling high concentrations of gaseous sulfur dioxide, an air pollutant, and ingesting small, regulated amounts in food. Air pollution from industrial sources and fossil fuel combustion can lead to significant respiratory irritation and lung damage, especially with long-term exposure. In contrast, the potential for harm from food consumption is limited to those with specific sensitivities.
Conclusion
In summary, whether sulfur dioxide preservative is bad for you depends entirely on your health profile. For most healthy people, consuming regulated amounts in foods like dried fruit and wine is not harmful. However, for a small but important portion of the population, particularly asthmatics and those with sulfite sensitivities, it can trigger adverse and sometimes serious reactions. The key takeaway is to be aware of your own sensitivities and read food labels carefully to make informed dietary choices. For further authoritative information on sulfite sensitivity, consult the Centers for Disease Control and Prevention.
What are sulfites and where are they found in food?
Sulfites are a group of sulfur-based compounds that includes sulfur dioxide, which are used as preservatives and antioxidants in a wide range of foods and beverages, such as wine, dried fruit, and processed meats.
Why is sulfur dioxide added to dried fruit?
Sulfur dioxide is added to dried fruit, like apricots, to prevent microbial spoilage, act as an antioxidant to prevent browning, and maintain the fruit's vibrant color and appearance during storage.
How can I tell if I have a sulfite sensitivity?
Symptoms of a sulfite sensitivity often resemble those of an allergy, such as wheezing, coughing, hives, or stomach pain, and usually occur shortly after consuming sulfite-containing foods. A healthcare provider can conduct an oral challenge test to confirm sensitivity.
Are wines labeled "no added sulfites" completely sulfite-free?
No, all wines contain naturally occurring sulfites produced during the fermentation process. A "no added sulfites" label indicates that no additional sulfites were used beyond the natural production, but they are not 100% free of sulfites.
Can I avoid sulfur dioxide by eating organic products?
Yes, organic dried fruits are typically produced without the use of sulfur dioxide and other synthetic preservatives. Checking the label of organic products is the best way to ensure they are sulfite-free.
What is the difference between ingesting food sulfites and inhaling sulfur dioxide gas?
Ingesting small, regulated amounts of sulfites in food primarily affects those with sensitivities, while inhaling high concentrations of sulfur dioxide gas, an air pollutant, can cause general respiratory irritation and lung damage in anyone.
What are the symptoms of an allergic reaction to sulfites in wine?
Symptoms of an allergic-type reaction to sulfites in wine can include asthma-like symptoms (wheezing, chest tightness), hives, and headaches, though the latter can also be caused by other compounds like histamines.
