Shrimp in a serving dish on a table with a fork - by Doug Cook RD

Ever Heard Of Sulfite Allergy?



Shrimp in a serving dish on a table with a fork


Sulfites versus sulphites. What’s the difference?


None, it’s a matter of spelling. US versus British, like flavor versus flavour!


Sulfites are one of the Top 10 food allergies flagged in Canada to watch out for. Along with dairy, eggs, mustard, peanuts, seafood, soy, tree nuts, sesame and wheat, sulfites are a real problem in susceptible people (1).


Most of the population can easily metabolize sulfites. For the other 0.5-1% of the general population and for 5-10% of people with asthma, not so much. Sulfite sensitivity is a real thing, but it’s not a true allergy according to many allergists. An allergy involves some abnormal response of the immune system, and the immune system is not involved in the same way. It is some form of intolerance or sensitivity.


Sulphites. One of the Top 10 Priority Food Allergens


The exact cause of a sulfite reaction isn’t well understood. Some experts believe it occurs after inhaling the sulfites powdered on foods while eating them. Chewing the food causes the sulfites to be airborne which are then inhaled leading to difficulty breathing or wheezing. The people most at risk are asthmatics, especially those who use steroid medications. Steroids are powerful drugs that suppress the immune system and prevent it from over-activation. When the balance of activation and deactivation occurs, anaphylaxis can follow. Sulfite sensitivity has lead to death in those with asthma (2).


Pouring red wine from bottle into glass with wooden wine casks on background

What are sulfites and why are they used?

Sulfites are substances that naturally occur in some foods and the human body. They are also regulated food additives that are used as preservatives to maintain food colour and prolong shelf-life. Sulfites also prevent the growth of micro-organisms and are used to maintain the potency of certain medications. Sulfites are also used to bleach food starches (e.g., potato) and in the production of some food packaging materials (e.g., cellophane).


Particularly prevalent in dried fruit like apricots, sulfites preserve the light colouring after drying. Sulfite free dried apricots will be brown, not the intense orange colour you might be used to. Wine makers also use sulfites to maintain freshness and prevent oxidation. In the ’70s and ’80s, the use of sulfites as food preservatives drastically increased, as did the number of people who began experiencing reactions.


Common symptoms of sulfite sensitivity

Symptoms of sulfite sensitivity in susceptible people typically starts within 2 to 30 minutes and can linger for up to 48 hours after exposure. Like with most health-related issues, there is a lot of variability with a reaction between people. Symptoms include:

  • headache
  • rash
  • hives
  • swelling of the mouth and lips
  • wheezing or trouble breathing
  • asthma attack (in people with asthma)
  • anaphylaxis


A ramekin dish filled with dried apricots on a wicker place mat


How much sulfites can you consume?

This is the million dollar question. Like most sensitivities, dose matters. Many with sensitivities to sulfites will be able to consume small amounts. The trick is to not over do it. Even foods with small amounts of sulfites add up. Think of it like a ledger, if you added up everything you ate and drank, what would that total amount be? This is referred to as ‘stacking’.


The exact safe amount for those with sulfite sensitivity is unknown but it appears to be in the 10-50 p.p.m. range. There isn’t any upper limit for the rest of the population. While it’s next to impossible to count ‘ppm of sulfites’ throughout the day, do your best to avoid foods that have a lot of them. I believe that choosing organic foods is a personal choice for the most part. When it comes to avoiding sulfites though, choosing certified organic versions of problematic foods (dried fruit for example) is an easy way to avoid sulfites.


FUN FACT: red wine gets more blame for causing headaches. White wine typically has more sulfites than red and all wines have much less than dried fruit. Who knew? 🙂


Foods that typically have sulfites added

  • Alcoholic/non-alcoholic beer, cider, wine
  • Apple cider
  • Baked goods
  • Bottled lemon and lime juice/concentrate
  • Canned/frozen fruits and vegetables
  • Cereal, cornmeal, cornstarch, crackers, muesli
  • Condiments
  • Deli meats, hot dogs, sausages
  • Dressings, gravies, guacamole, sauces, soups, soup mixes
  • Dried fruits and vegetables
  • Dried herbs, spices, tea
  • Fish
  • Fresh grapes
  • Fruit fillings, fruit syrups, gelatine, jams, jellies, marmalade, molasses, pectin
  • Fruit/vegetable juices
  • Glazed/glacéed fruits
  • Processed potatoes (such as frozen French fries)
  • Snack foods
  • Soy products
  • Starches
  • Sugar syrups
  • Tomato paste/pulp/purée
  • Vinegar, wine vinegar


Read labels to avoid sulfites

Sulfites are labelled if used in food processing. They are also labelled when they are present in amounts over 10 p.p.m. People with sulfite sensitivity should avoid food products with the following chemicals in the ingredient list:

  • sulfur dioxide
  • potassium bisulphite / bisulfite
  • sulfurous acid / sulphurous acid
  • sodium bisulfite   / bisulphite
  • potassium metabisulfite / metasulphite
  • sodium metabisulfite / metabisulphite
  • sodium sulfite / sulphite


Strategies to limit your intake of sulfites

  1. Always check the labels and ingredient list for sources of sulfites (see list above)
  2. For potentially problematic foods (like dried fruit, wine etc), choose certified organic versions
  3. Deli meats typically have added sulfites. Choose fresh more often
  4. Consider unassuming sources when dining out like spices, condiments, desserts with candied fruit, noodle or mixed rice dishes
  5. Frozen or prepared products that have pre-cut food ingredients that normally brown (potatoes)
  6. Vending machine foods
  7. Prepared foods at the grocery store deli section that aren’t packaged or labelled: salads, meats, pasta salads


Frozen french fries in a serving dish


Doug Cook RDN is a Toronto based integrative and functional nutritionist and dietitian with a focus on digestive, gut, and mental health.  Follow me on Facebook, Instagram and Twitter.

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