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A guide to sulphite allergy

What is sulphite allergy?

Sulfa is an ingredient found in many antibiotics and medications. Sulphites are used as a preservative in foods and drinks. Sulphites also occur naturally in grapes and in humans! Sulphate salts are used in medications, personal hygiene products, and many other daily use items. Sulphates also occur naturally in humans. Finally there is the chemical element sulphur (yep you've guessed it, humans also have sulphur naturally - about 140 grams of the stuff) - known in ancient times as brimstone!

Sulphur (or Sulfur)

Sulphur atomic element 16 What exactly is sulphur? Sulphur is a base chemical element (pictured left) and can be found in a huge number of drugs and chemicals around the world. This element can be found in sulphites, sulfa, and sulphates. In fact they all get their name from sulphur. However, the amount of sulphur in any of these compounds is so infinitesimally small, medical researchers do not believe that it could possibly be blamed for any allergies.

Sulphur is readily available in protein rich foods and is stored in all body cells, especially the skin, hair, and nails. If needing extra sulphur you can get it from eating an egg a day or extra garlic and onions - there are minimal health concerns about sulphur deficiency or toxicity (no clearly defined symptoms exist with either condition), excess amounts are eliminated through the urine or in the faeces.

Sulphites (or Sulfites)

What are sulphites? Sulphites are present in many foods such as ready meals, pizza, wine and beer to maintain food colour and prolong shelf life. Whilst it acts as a preservative, it can cause minor irritations, however asthmatics and those who are sensitive to the irritant effect of sulphites can have severe reactions.

Sulphites are also present in the human body. We make sulphites from protein (chains called amino acids), some of these amino acids contain sulphur. From these we make homocysteine (too much of which can damage arteries and unborn babies), we then make cysteine from homocysteine – this is good news! Cysteine is an antioxidant that helps fight viruses and keeps your heart beating smoothly. However, too much of it overexcites the brain and is linked to asthma (this is why asthmatics are more likely to suffer from sulphite sensitivity). From the sulphites converted from cysteine, we make sulphates. Sulphate is anti-inflammatory and anti-depressant. It is needed for making stomach acid and digestive enzymes, it keeps your gut wall healthy and detoxifies chemicals made by the body and others from the environment. This probably protects us from cancer.

If you are allergic or sensitive to sulphites, it is important to avoid them as far as you can. You can avoid food with additives, but you cannot avoid making sulphite. It is important to make sure that you process it as efficiently as you can. The enzyme involved in converting toxic sulphite into useful sulphate is called sulphite oxidase. The enzyme needs enough molybdenum and riboflavin (vitamin B2) in order to work efficiently.

Sources of molybdenum

Molybdenum is a trace element found in a wide variety of foods. Foods that grow above ground - such as peas, leafy vegetables (including broccoli and spinach) and cauliflower - tend to be higher in molybdenum than meat and foods that grow below the ground, such as potatoes. Major food sources of molybdenum include pulses, grains and nuts. Red cabbage and buckwheat are some of the best foods to increase your intake. You can also take molybdenum supplements.

Sources of riboflavin (vitamin B2)

Major sources of riboflavin include milk and other dairy foods. Eggs, green leafy vegetables, mushrooms, rice and enriched bread and grain products (like fortified cereals) also contain smaller amounts. UV light can destroy riboflavin, so ideally these foods should be kept out of direct sunlight.Vitamin B2/Riboflavin supplements are also available.

Replacing high-sulphite foods

You are advised to go organic - organic producers use far less sulphite additives (the Soil Association estimates they use around 25% of the legal maximum on average). You can shop with us for only organic foods by using our organic filter, simply click on 'filter your shop' on the left hand side of the shop page and choose organic as the filter.

Swap vinegars for fresh lemons and limes

Replace bought dressings with cold pressed oils from nuts or seeds, olive oil and fresh lemon juice (make sure you buy the organic version of this - the non-organic usually has sulphur dioxide added)

Apricots/sultanas etc with non-sulphited organic ones. Watch out for any 'brightly' coloured dried fruits - most likely they have SO2 added to maintain their colour.

Stock cubes, gravies with homemade or organic brands such as Kallo or Marigold.

Frozen and dried foods with fresh

Bought juices with freshly made juices or organic juices

Sulphite labelling

EU food labelling rules require pre-packed food sold in the UK to show clearly on the label if it contains sulphur dioxide or sulphites at levels above 10mg per kg or 10mg per litre (or if one of its ingredients contains it). We do try to keep all our product listings as up-to-date as possible but you’re advised to always double-check the packaging before consumption. We can provide product specifications for larger commodities upon request – just email webshop@realfoods.co.uk with the product you are interested in and we’ll do our best to get the latest information for you.

Here's a link to our health advice on Low-Allergen diets, that can help manage sensitivities.

There are quite a few different names to watch out for on the ingredients list, only E220 - sulphur dioxide is a permitted addition to organic foods, the others will only be found in non-organic foods. Their E numbers are as follows:

  • 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

You will also want to watch out for: Potassium bisulphite/Potassium metabisulphite, Sodium bisulphite, sodium dithionite, sodium metabisulphite, disodium sulphite, sulfite, Sulfur dioxide, Sulphiting agents, Sulphurous acid.

Foods high in sulphites:

  • Alcoholic and non-alcoholic beer, cider and wine - follow this link for our article on organic and low-sulphite wines
  • Bottled lemon and lime juices and concentrates
  • Canned and frozen fruits and vegetables
  • Cereal, cornmeal, cornstarch, crackers and muesli
  • Condiments, for example, coleslaw, horseradish, ketchup, mustard, pickles, relish and sauerkraut
  • Dehydrated, mashed, peeled and pre-cut potatoes, and frozen french fries
  • Deli meats
  • Dried fruits and vegetables, such as apricots, coconut and raisins, sweet potato
  • Dried herbs, spices and teas
  • Fresh grapes, lettuce
  • Fruit fillings and syrups, gelatin, jams, jellies, preserves, marmalade, molasses and pectin
  • Fruit and vegetable juices
  • Glazed and glacéed fruits, for example, maraschino cherries
  • Potatoes
  • Snack foods
  • Starches, (for example, corn starch, potato starch)
  • Soy products
  • Sugar syrups, for example, glucose, glucose solids, syrup dextrose, corn syrup, table syrup
  • Tomato pastes, pulps and purées
  • Vinegar and wine vinegar


Free from SLS and SLES shampooIf you are sensitive to sulphites you are not necessarily sensitive to sulphates (and vice versa.)

Sulphates are a salt of sulphuric acid. Sulphates are found in household and bathroom products, including shampoos, washes, cleaners and detergents. In shampoo, two in particular are used - Sodium Lauryl Sulphate (SLS) and Sodium Laureth Sulphate (SLES). They create a lather and help strip away grease. However some people are sensitive to them and SLS and SLES free products are available. Just to be confusing some of the ingredients may end in sulphate but still be labelled sulphate-free. For example, sodium coco sulphate is derived from coconuts, others may be derived from corn or oats and also will not be salts of sulphuric acid.

Sulphates have been linked with damaging dyed or highlighted hair.

Faith In Nature and Green People have no SLS, SLES or parabens in their range. There are also a few sulphate free shampoos here.

Dr Bronner uses natural oils and turns them into soap and glycerin without SLS or SLES. Their SAL Suds cleaner mix does contain sodium leureth sulphate however so avoid if you are sensitive.

Since 2012 Kingfisher toothpastes have been SLS free and use only natural ingredients with no preservatives. Sarakan is also SLS and SLES free.

Sulpha drugs (or Sulfa)

Allergies to sulphonamides, also known as sulpha, are common. Sulpha drugs were the first successful treatment against bacterial infections in the 1930s. Today, sulphonamides are still used in antibiotics, as well as a host of other medications such as diuretics and anticonvulsants. Nearly 3 percent of people are sensitive to sulfonamides. Because of the prevalence of sulpha allergies, doctors must use care when prescribing them to patients.

It is important to make a distinction between sulfa drugs and other sulphur-containing drugs and additives, such as sulphates and sulphites, which are chemically unrelated to the sulfonamide group, and do not cause the same hypersensitivity reactions seen in the sulfonamides.

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