Sulphites are preservatives that can trigger serious reactions in people who are sensitive to them. Senior HFG nutritionist Rose Carr reports.
People have used sulphites to preserve their food since ancient Roman times. In the modern world, however, some of us can experience adverse effects when we eat foods or consume drinks that contain these compounds.
What are sulphites?
Sulphites, or sulfites, occur naturally in the human body, as well as in fermented products such as wine and vinegar. Their antioxidant and antimicrobial properties enable them to not only prevent bacterial growth and browning in foods, but also minimise spoilage and help food retain colour and flavour.
Which foods contain sulphites?
Manufacturers add sulphites to a wide range of foods and drinks, and even to some medications.
These preservatives can be present in wine, beer, fruit juice, cordial, ginger beer, cider, wine vinegar, salad dressing, sausages, dried soup, dried fruit, muesli, snack bars, maraschino cherries, dessert toppings and gelatine, among other products.
When a food or drink contains added sulphites in concentrations of 10mg per kilo or more, the Food Standards Australia New Zealand Code requires the ingredients panel to list them. These food labels must signal the presence of a sulphite by listing its individual name or code number (220 to 228).
Scan food labels for these numbers
220 sulphur dioxide
221 sodium sulphite
222 sodium bisulphite
223 sodium metabisulphite
224 potassium metabisulphite
225 potassium sulphite
228 potassium bisulphite
What’s the problem with sulphites?
Most of us have no unwanted reaction to sulphites, and hence have no reason to avoid them. But people who are sensitive to these preservatives may suffer symptoms such as wheezing, diarrhoea, stomach ache, hives or swelling. These reactions can be mild, but in very rare cases, they could be life threatening.
Research shows that sulphites can trigger negative reactions (usually chest tightness, wheezing and coughing) in 5–10 per cent of people with asthma. Although these reactions are more likely to occur when asthma is poorly controlled, sulphites can also trouble people who have no history of asthma whatsoever.
It’s unclear why some people react badly to sulphites. These compounds act as a preservative by releasing sulphur-dioxide gas, which is an irritant. When you drink beer or wine that contains these preservatives, you inhale and ingest sulphur-dioxide gas, which may explain why drinking can give rise to such troublesome symptoms so quickly. Some of the people who react to sulphites may produce insufficient amounts of the enzyme that breaks down sulphur dioxide. And in extremely rare cases, people may have an actual allergy to sulphites, so their unwelcome reaction is simply an immune-system response.
How do I find out if sulphites are causing my problems?
It’s important not to self-diagnose a sulphite sensitivity or allergy, as other factors can cause the same symptoms. Some of us are sensitive to the natural chemicals in food, including glutamates, salicylates and amines. And if so, we may also be sensitive to one or more of the common food additives, of which sulphites is just one group.
To find out whether sulphites are provoking your symptoms, see your GP. He or she might recommend an allergy test, even though most people who have a sensitivity to sulphites don’t have a true allergy, and there’s no valid test for sulphite intolerance.
The Australasian Society of Clinical Immunology and Allergy (ASCIA) warns against having unorthodox tests for diagnosing food allergies and intolerances.
These tests include cytotoxic food testing, allergy-elimination techniques, Vega testing, hair analysis, kinesiology, iridology, pulse testing, reflexology and IgG-antibody testing.
For more information on these tests and their methods, visit the ASCIA website.
What if I’m reacting to sulphites in foods?
If your doctor suspects that you have a food intolerance, an accredited practising dietitian who specialises in this field can help supervise a temporary elimination diet, which is the only reliable way to diagnose chemical intolerances.
It’s important to have a health professional guide you through this kind of process, rather than (perhaps) unnecessarily cutting a wide range of foods from your diet, as this could disadvantage your overall health.