Sulphites are used as preservatives in some foods, and can cause allergy-like symptoms in people with asthma and allergic rhinitis.
Allergy to sulphites is rare, affecting fewer than 1 in 50 people. However, up to around one in eight people with asthma may be affected.
Sulphites preserve food using sulphur dioxide gas. Once the food starts to be digested, gas can be released up into the airways where it may cause irritation.
A person can develop sensitivity to sulphites at any time in life, and the cause of sensitivity is unknown. For a person who is sensitive to sulphites, a reaction can be mild or life threatening.
Although sulphites are no longer used on most fresh foods, they still can be found in a variety of cooked and processed foods. They also occur naturally in the process of making wine and beer.
Avoiding foods that contain or are likely to contain sulphites is the only way to prevent a reaction. If you are sensitive to sulphites, be sure to read the labels on all food items. When eating out, ask the chef or waiter if sulphites are used or added to food before or during preparation.
Food additives or E numbers containing sulphites can be found listed on food packaging:
- E220 Sulphur dioxide
- E221 Sodium sulphite
- E222 Sodium hydrogen sulphite
- E223 Sodium metabisulphite
- E224 Potassium metabisulphite
- E226 Calcium sulphite
- E227 Calcium hydrogen sulphite
- E228 Potassium hydrogen sulphite
- E150b Caustic sulphite caramel
- E150d Sulphite ammonia caramel
Examples of foods that may contain sulphites include:
- Baked goods
- Soup mixes
- Canned vegetables
- Pickled foods
- Dried fruit
- Potato crisps
- Beer and wine
- Vegetable juices
- Sparkling grape juice
- Apple cider
- Bottled lemon juice and lime juice
- Many condiments
- Fresh or frozen prawns
- Maraschino cherries
- Dehydrated, pre-cut or peeled potatoes