Sulphites (or sulfiting agents) are a group of chemical compounds, including sulphur dioxide (E220), sodium sulphite (E221), and potassium metabisulphite (E224), used widely in the food industry to prevent microbial spoilage, maintain color, and extend shelf life. They are effective antioxidants and enzyme inhibitors, which is why dried apricots stay orange and wine doesn't turn to vinegar.
Understanding Sulphite Sensitivity
For most of the population, consuming sulphites poses no health risk. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has established an Acceptable Daily Intake (ADI) of 0.7 mg per kg of body weight per day. The human body has an enzyme, sulfite oxidase, which rapidly converts sulphites into harmless sulfates, which are then excreted.
However, in a small percentage of people—estimated at around 1% of the U.S. population and potentially 5-10% of people with asthma—this conversion process may be less efficient, leading to adverse reactions. These are typically intolerance reactions rather than true immune-system-mediated allergies, but the symptoms can be significant and allergy-like.
Common symptoms of sulphite sensitivity include:
- Wheezing, chest tightness, and coughing (most common, especially in asthmatics)
- Hives (urticaria) and itching
- Swelling of the face, tongue, or throat (angioedema)
- Nausea, abdominal pain, and diarrhea
- Rarely, severe anaphylactic reactions
Reactions can occur within minutes or hours of consumption.
Foods That Commonly Contain Sulphites
Sulphites can be naturally occurring in foods like some fermented products, or they can be added as preservatives. The highest levels of sulphites are generally found in specific processed foods.
High Sulphite Foods (over 100 ppm)
- Dried fruits (apricots, etc., but generally not dark raisins/prunes): Mean levels can be over 1500 mg/kg.
- Wine and beer: Formed during fermentation and often added; mandatory labeling required above 10 ppm.
- Bottled lemon and lime juices (non-frozen): High concentrations to maintain freshness.
- Molasses, sauerkraut, pickled cocktail onions: Preservative use is common in these items.
Moderate/Low Sulphite Foods (10-99 ppm)
- Processed potatoes: Frozen fries, dehydrated flakes, pre-cut or peeled potatoes.
- Gravies, sauces, soup mixes: Used in various ready-made mixes.
- Shrimp (fresh or frozen): Used to prevent black spots.
- Some baked goods: Especially those containing dried fruits.
Foods with naturally occurring sulphites, like some onions, garlic, and ginger, generally do not need to be labelled unless treated with additional sulphites. It is illegal in many places, including the US, to add sulphites to raw fruits and vegetables (except potatoes) intended to be eaten fresh.
Sulphites vs. No Sulphites: Key Differences
| Feature | Foods With Sulphites | Foods Without Sulphites |
|---|---|---|
| Appearance | Bright, preserved color (e.g., bright orange dried apricots) | Often darker or browned appearance (e.g., dark brown dried apricots) |
| Shelf Life | Extended shelf life, inhibits microbial growth | Shorter shelf life, quicker spoilage |
| Flavor | Preserved flavor profile | Flavor may change more quickly with oxidation |
| Labeling | Must be declared if >10 ppm (e.g., Sulfur Dioxide, Sodium Metabisulphite, E220-E228) | No specific labeling required |
How to Avoid Sulphites
For those who are sensitive, avoiding sulphites requires vigilance:
- Read Labels Carefully: Look for the words "sulphites" or "sulfites" in the ingredient list. Also, watch for the specific additive numbers E220 through E228 or chemical names like sodium bisulphite or potassium metabisulphite.
- Be Aware of the 10 ppm Rule: In many countries, if a food contains less than 10 parts per million of sulphites, it does not need to be declared, as this amount is considered insignificant.
- Avoid Unlabeled Foods: Exercise caution with foods from bulk bins, salad bars, or certain restaurant dishes where ingredients and processing aids might be unclear. When dining out, always ask your server about the use of sulphites in preparation.
- Choose Fresh and Unprocessed: Stick to fresh fruits, vegetables, and plain cooked meats, which typically do not contain added sulphites.
- Home Prep: Prepare food from scratch using whole ingredients to control exactly what goes into your meal.
Conclusion: Navigating Sulphites for Your Health
Should you avoid sulphites? For the majority, the answer is no, as sulphites are safe food additives within acceptable intake limits. However, if you are part of the sensitive population, particularly if you have asthma, managing or avoiding sulphite intake is essential to prevent adverse health reactions. By understanding which foods contain them and carefully reading labels, you can confidently navigate your diet and prioritize your well-being. If you suspect you have a sensitivity, it's vital to consult with a healthcare professional or an allergist for a proper diagnosis and management plan.
