However you spell them, sulfites / sulphites and sulfur / sulphur dioxide are not considered one of the eight key allergen groups in the US, but they are one of the 14 allergens in the UK / EU.
They are used as preservatives, and are therefore found in a lot of processed foods, especially alcoholic drinks and dried / glazed fruits, but also deli and processed meats, tinned fish, condiments, preserves, pickles and many more foods. It is the sulphur dioxide (SO2) which acts as the preservative; the various sulphite salts release it naturally when they come into contact with water.
There could be several mechanisms behind sulphite sensitivity.
The most common symptom is wheezing, and perhaps coughing, in those with underlying asthma. It seems that SO2 aggravates sensitive airways in some way, causing breathing difficulties.
Some may experience runny nose and rashes, and this may be due to histamine release in the body, which may occur in some as a response to sulphite exposure. Allergy-like symptoms such as these, and others such as nausea, may also be due to a natural deficiency in the enzyme sulphite oxidase, which helps break down SO2. IgE-mediated allergies to sulphite preservatives also seem possible.
As there are no tests to help with diagnosis, the only means may be through supervised challenge testing.
In the UK / EU the sulphites are interesting because they have to be declared as allergens not when they’re added to a product, necessarily, but when they are added to a product (or a component ingredient) and are present above a certain threshold — 10mg/kg or 10mg/litre — the only allergen for which this kind of rule exists. The threshold applies to the food as it is to be eaten (ie, after any preparation by the consumer) and includes naturally present sulphites in the food, as well as any added.
On EU labelling, you will see the sulphur dioxide or sulphite salt highlighted. In alcoholic drinks which don’t require ingredient labelling, you should see “Contains: sulphites”. The main E numbers to watch out for are E220 (sulphur dioxide) through to E228 (potassium hydrogen sulphite).
In the US, sulphites also have to be declared in the list of ingredients, unless they appear at ‘incidental’ levels under 10 parts per million (10ppm) — mirroring the situation in the EU, in effect.
Sensitivities to the sulphites vary a lot. Low and/or natural levels of sulphites occur in many food products without declaration.
The most common problem sulphite sensitives encounter is reactions to wine.
Sulphite production during fermentation is natural, and this is widely considered harmless as it is ‘bound’.
But sulphur is usually added to most wines at various stages of production to prevent oxidisation and spoilage. Some will do its job of preservation, and react within the wine safely as it does so, but, depending on the quantities used by the winemaker, some ‘free’ sulphur / sulphite will remain in the wine, and it is this which can cause problems. White wine, especially sweet wine, is usually worse.
Organic wine is often touted as likely to be lower in sulphites and, while this may be sometimes true, added sulphite preservatives are permitted in organic wines, so you may still react. That said, organic is a desirable quality for many consumers, and stockists such as Organic Wine Club, offer a ‘No Added Sulphites’ selection — some of which come in at under 10ppm (natural) sulphites, and some which contain more than 10ppm, and for which a ‘contains sulphites’ declaration on the label can be found.
Because of this naturally occurring sulphite, strictly speaking there is no such thing as ‘sulphite free’ wine, but stockists such as Good Wine Online, who specialise in wines for sulphite sensitives, use the term to describe wines which have been made with no added sulphite at all.
You may also see ‘low sulphite’ but this has no quantitative legal definition and sulphur may have been added. The term NSA (No Sulphur Added) is also used, which is more reassuring.
There are a few products on the market to help sulphite sensitives, though it’s uncertain how effective they are in practice.
Sulfite test strips — which you should be able to find online at Amazon, for example — are handy to test the (free) sulphite content of liquids, although not all are recommended specifically for wine.
Meanwhile The Wand is a portable stirrer to help filter out sulphites (and histamines, which are more of an issue in red wine). See it here. There’s also The Wave which works on a similar principle, but for a bottle of wine; though at $10 each (2 for $19.99) it seems more worthwhile just buying the low sulphite wine to start with. See it here.
Drop It drops — “drop the headache, enjoy the wine” — are liquid drops to add to your wine. They contain food-grade hydrogen peroxide to oxidise the free sulphite. Tannins may also be reduced, meaning a stringent wine may become smoother.
The US does not permit sulphite in meat. Most sausages in the UK have sulphites. Your best bet is to look at organic options.
Eversfield Organic Farmhouse Pork Sausages are sulphite free, and free of all other allergens too. From Ocado. (Ocado, incidentally, offer a ‘sulphite free’ search option.)
Peelham Farm offer organic sausages and burgers which are stated sulphite free.
For a supermarket option, try Sainsbury’s Organic Pork Sausages.
Orange dried apricots are likely to be sulphite containing. Darker, unsulphured apricots are usually available, for instance in health and whole food stores.
A lot of dried fruit, such as figs, prunes and raisins, may be preserved with non-sulphite preservatives (eg potassium sorbate), and some, such as dates, may not always have added preservative at all. Organic dried fruit is likely to be OK.
There are some. Sulphites reduce the vitamin B1 (thiamin) in meats. Studies suggest sulphites can reduce beneficial bacteria in the gut.
For an excellent, detailed and referenced article on sulphite sensitivity, see Dr Janice Joneja’s article on Foods Matter here.