What are Sulphites?
Sulphites, also spelled sulfites, are a group of sulphur-based compounds that act as preservatives, antioxidants, and bleaching agents. They are used in both the food and pharmaceutical industries to maintain the color and prolong the shelf life of products. While some sulphites occur naturally during the fermentation of wine, they are most often added to foods and medications. These compounds have been used for centuries, with the ancient Romans using them to sanitize wine vessels. However, their widespread use in the food industry only gained significant attention in the 1970s and 80s following reports of severe adverse reactions.
The Mechanisms Behind Sulphite Sensitivity
For the majority of people, sulphites are safely metabolized by the body without any adverse effects. However, in sensitive individuals, a number of proposed mechanisms can trigger a reaction. While not a true allergy involving the immune system (IgE-mediated), sulphite sensitivity can cause allergy-like symptoms that are sometimes severe.
Possible triggers include:
- Sulphur Dioxide Inhalation: When sulphite-containing foods are consumed, especially in acidic environments like the stomach, they can release sulphur dioxide (SO2) gas. Inhaling this irritant gas can trigger bronchoconstriction, leading to respiratory issues like wheezing and chest tightness, particularly in asthmatics.
- Sulphite Oxidase Deficiency: A small number of individuals, particularly those with asthma, may have a low level of the enzyme sulfite oxidase. This enzyme is responsible for breaking down sulphites into harmless sulfates. A deficiency can lead to an accumulation of sulphites in the body, triggering adverse reactions.
- Histamine and Mediator Release: In some sensitive individuals, sulphites may cause the release of other chemicals, such as histamine, which can cause or worsen symptoms.
Symptoms of Sulphite Reactions
Reactions to sulphites can vary widely in severity, ranging from mild discomfort to life-threatening anaphylaxis in extremely rare cases. The most common reactions involve respiratory symptoms, especially in asthmatic individuals.
Commonly reported symptoms include:
- Respiratory: Wheezing, coughing, chest tightness, shortness of breath, and nasal congestion.
- Gastrointestinal: Abdominal pain, cramps, nausea, vomiting, and diarrhea.
- Skin: Hives (urticaria), redness, itching, and swelling of the face, lips, or tongue.
- Cardiovascular: Paleness, a weak pulse, flushing, or dizziness.
Who is at Risk?
While anyone can develop a sulphite sensitivity at any age, certain populations are at a significantly higher risk.
- Asthmatics: This is the most at-risk group, with studies estimating that 5-13% of people with asthma may experience adverse reactions to sulphites. Those with more severe or poorly controlled asthma appear to be at greater risk.
- Sensitive Individuals: Beyond asthmatics, a small portion of the general population can also develop a sensitivity, which is distinct from a true allergy.
- Children: Some studies indicate that sulphite sensitivity may be more common in children with chronic asthma.
A Comparison of High vs. Low Sulphite Foods
Navigating food labels is crucial for individuals with sulphite sensitivity. Here is a comparison of common food items with high sulphite content versus those that are typically low or free of sulphites.
| High Sulphite Content | Low or Sulphite-Free Content |
|---|---|
| Dried fruits (apricots, raisins) | Fresh fruits (not pre-sliced) |
| Wine and beer (especially sweeter wines) | Certified organic wines (no added sulphites) |
| Processed potatoes (fries, dried flakes) | Fresh potatoes |
| Sausages and deli meats | Fresh, unprocessed meats |
| Bottled lemon and lime juice | Freshly squeezed lemon and lime juice |
| Condiments (vinegar, pickled foods, some sauces) | Unprocessed spices and herbs |
| Baked goods (containing dried fruits) | Freshly baked breads (check ingredients) |
Beyond Food: Other Sources of Sulphites
Sulphites are not limited to food and drink. They are also used in a variety of other consumer products, which can pose a risk for highly sensitive individuals.
- Pharmaceuticals: Sulphites are used as a preservative in some medications, including certain injections, creams, and eye drops. While reactions are rare, it is important for sensitive individuals to discuss this with their pharmacist or doctor.
- Cosmetics: Products like hair dyes, skin lighteners, and moisturisers can contain sulphites. Contact with these products can lead to skin reactions in sensitive people.
The Nutritional Impact of Sulphites
In addition to triggering sensitivities, sulphites can have a negative nutritional impact by destroying or reacting with certain vitamins. Specifically, they can degrade thiamine (vitamin B1), which can lead to a deficiency if sulphite intake is consistently high. While this is less of a concern for the general population with a balanced diet, it's an additional consideration for those seeking to limit their sulphite exposure. Research has also indicated that sulphites may inhibit the growth of certain beneficial gut bacteria.
Conclusion: Navigating Sulphite Exposure
While sulphites play a beneficial role in food preservation and production, their potential for harm to sensitive individuals is well-documented. The key to managing a sulphite sensitivity is awareness and careful label reading. Knowing which foods, beverages, and other products contain sulphites empowers individuals to make informed choices. If you suspect you have a sulphite sensitivity, consulting a healthcare professional is recommended for a proper diagnosis and management plan. By staying vigilant, sensitive individuals can effectively avoid triggers and minimize their risk of adverse reactions.
What to Do If You Suspect Sulphite Sensitivity
If you experience symptoms like wheezing, hives, or gastrointestinal issues after consuming sulphite-containing products, it is important to take action.
- Read Labels: The FDA requires that any product containing 10 parts per million or more of sulphites must be declared on the label. Check ingredient lists for terms like sulfur dioxide, sodium bisulphite, potassium metabisulphite, and other related agents.
- Keep a Food Diary: Documenting what you eat and any subsequent symptoms can help you and your doctor identify specific triggers.
- Consult a Professional: A doctor can help confirm a sensitivity and provide guidance. In some cases, a supervised oral challenge test may be performed.
- Consider Alternatives: Look for low-sulphite or preservative-free versions of foods and drinks that commonly contain sulphites, such as organic wines or sun-dried tomatoes.
- Carry an Epinephrine Auto-Injector: In the rare case of severe anaphylactic reactions, an epinephrine auto-injector is a first-line treatment and should be carried by those at risk.
Making a Healthy Choice for Your Body
For most people, sulphites are not a major health concern. However, for the percentage of the population with asthma or a sensitivity, they can cause significant, and sometimes severe, reactions. Being aware of the potential risks and taking steps to manage exposure can help sensitive individuals live a healthier, symptom-free life. It's about personal health, and understanding your body's unique needs.
Conclusion
In summary, while sulphites serve a practical purpose in preserving food and medicine, they are not universally benign. For a specific subset of the population, including many asthmatics, sulphites are harmful and trigger adverse reactions ranging from respiratory distress to skin and gastrointestinal issues. The exact mechanism is still under investigation, but it is clear that sensitivity, often caused by the release of irritant sulphur dioxide or enzyme deficiencies, is the primary reason for these adverse effects. Careful reading of product labels and an awareness of common sources are the most effective strategies for managing a sulphite sensitivity.
