Sulphite sensitivity a danger for asthma sufferers

Jan*, a YourLifeChoices member, wrote in to us about a little-known allergy that may be more common than most people realise. An allergy is an increased sensitivity to a substance, known as an allergen. In this case, the allergen is sulphites. While we regularly hear about allergies and intolerances to lactose and gluten, few people have heard of sulphite sensitivity.

“Eating out is hazardous,” Jan warned. “Please help to get this allergy out there … the side-effects if we inadvertently eat something we shouldn’t – maybe because of poor ingredient listing – are not nice.”

Sulphites are naturally occurring minerals that can be found in some natural foods. Sulphites release sulphur dioxide gas, which acts as a preservative. They have been used since Roman times to preserve foods, drinks and medicines.

Sulphites is a term that describes these six substances:

  • sulphur dioxide
  • sodium sulphite
  • sodium bisulphite
  • sodium metabisulphite
  • potassium bisulphite
  • potassium metabisulphite.

While they are harmless for most people, some people are sulphite-sensitive and may react to them with allergy-like symptoms. Around 5 to 10 per cent of people with asthma are also allergic to sulphites. They can trigger symptoms such as wheezing, allergic rhinitis (hayfever-like symptoms) and hives. While not all people with this sensitivity have asthma, these reactions are more serious among people who do. Asthmatics may have a partial deficiency of the enzyme sulphite oxidase that helps to break down sulphur dioxide. For these people, sulphites can be life threatening.

Extreme responses to sulphites include dizziness, collapse, flushing, fast heartbeat, hives, wheezing, difficulty swallowing, tingling, stomach upset and diarrhoea. While sulphites have been known to cause anaphylaxis, it is a very rare response.

Sulphites, sulphates and sulphur
While they may all sound similar, these components interact differently with the body. For those of us who don’t have a degree in science, searching a sulphite allergy online can be confusing as so many terms sound similar, but do very different things. Elemental sulphur is sometimes used in gardening and isn’t known to cause reactions in sulphite-sensitive people, though may cause breathing difficulty when inhaled. Sodium lauryl sulphate is found in most shampoos and soaps, and sulphate is a component of some medicines, but these are not allergenic, so do not cause a reaction in people with sulphite-sensitivity.

Diagnosing sulphite-sensitivity
While some people may react positively to skin allergy tests to sulphites, there are currently no reliable blood or skin allergy tests for sulphite intolerance. Undergoing a food challenge with the supervision of a clinical immunologist or allergy specialist may be able to confirm or exclude sulphite sensitivity.

Where you’ll find sulphites
According to allergy.org.au, these are the most common sources of accidental exposure to sulphites.

Drinks: beer, wine, fruit juice, cordials, soft drinks and some tea.
Foods: gravy, biscuits, bread, sauces, dry potatoes, pickled onions, fruit toppings, maraschino cherries, maple syrup, jams, jellies, pies, pizza dough, gelatine and coconut.
Fruit: dried apricots and fresh some grapes.
Salad: while it is illegal in most countries to add sulphites to fresh salads, some restaurants may to preserve colour.
Meat: while it is illegal in most countries, sulphites may still be added illegally to minced meat and sausages. 
Crustaceans: sulphite powder is sometimes added to crustaceans to preserve their colour.
In the kitchen: vinegar, commercially produced lemon and lime juice

In Australia, it is mandatory by law to include the presence of sulphites on the packaging of foods. This will be made clear either by the word sulphite, or by the code number of the ingredient.

Code number

Ingredient

220

Sulphur dioxide

221

Sodium sulphite

222

Sodium bisulphite

223

Sodium metabisulphite

224

Potassium metabisulphite

226

Calcium sulphite

227

Calcium bisulphite

228

Potassium bisulphite

Managing a sulphite sensitivity
Unfortunately, there is no evidence to suggest that sulphite sensitivity reduces over time, and there is no proven method of desensitising the sensitivity. When shopping, it is important to read the labels on food, and when eating away from home, it’s important to alert staff of your allergy. Someone who experiences mild symptoms should carry an asthma puffer with them when they eat out, while people with more serious symptoms should carry a prescribed adrenalin autoinjector.

Had you previously heard of a sulphite allergy? Do you suspect you may have sulphite sensitivity?

*Not her real name.

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Disclaimer: This article contains general information about health issues and is not advice. For health advice, consult your medical practitioner.

Written by Liv Gardiner

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