Sulfites are chemicals that are used as preservatives to inhibit the browning and discoloration in foods and beverages during preparation, storage and distribution. Sulfites have been used in wine making for thousands of years. When consumed, some people find that sulfite-containing foods will cause uncomfortable symptoms, but what is sulfite allergy and its treatments?
What is a Sulfite?
These compounds are found in certain foods and beverages and in a variety of medications. The use of sulfites as preservatives in foods and beverages had increased dramatically in the 70’s and 80’s. Because of several cases of severe allergic reactions, the FDA banned sulfites in August of 1986. This resulted in prohibition of use of sulfites in fruits and vegetables.(1)
Sulfites are sulfur-based preservatives that can be used to prevent black spots of shrimp and lobster as well as inhibit the growth of microorganisms in fermented foods like wine and dough. It may also be used to maintain the stability and potency of certain medications. They can also be used to bleach food starches, to prevent rust and scale the boiler water that is used to steam food and even in the production of cellophane for food packaging.
These potentially toxic and harmful substances can cause nausea or diarrhea and precipitate asthma attacks in sensitive individuals. The “salad bar syndrome” is caused by sulfite sprays on vegetables to keep them fresh longer. A person can develop a sulfite allergy at any point in their life.(2)
Allergic reactions to sulfites were originally a problem focused on salad bars in restaurants, but this isn’t a the only recognized place for sulfite exposure. They are now used in potatoes, shellfish, alcohol and pharmaceutical drugs. Sulfites are added to many medications, including those given to treat asthma and allergic reactions.
Look out for these sulfite-containing ingredients on food labels:
- Sulfur dioxide
- Potassium bisulfate
- Potassium metabisulfite
- Sodium bisulfite
- Sodium metabisulfite
- Sodium sulfite
What is Sulfite Allergy?
Let’s consider the Canadian Food Inspection Agency’s list of top 11 food groups that cause the most frequent and severe allergic reactions. Eight of the names will be familiar to most: peanuts, tree nuts, milk, eggs, fish, shellfish, soy and wheat. However, the eleventh may be a surprise because it is sulfites.
In one percent of the population(mostly those with asthma), even tiny amounts of sulfites can cause reactions. About four percent of asthmatics are sensitive to sulfites. In Canada, they have gained enough attention to make CFIA’s top list because there have been more than 100 reports of sulfite-related anaphylaxis with at least one death.
It is still unclear what the scientific route of allergic inflammation due to sulfite sensitivity is. Sulfite allergy is a special case for allergists because they are chemical compounds rather than proteins, which is what the body normally has a reaction to. It is unclear whether sulfites cause the immune systems of some people to respond abnormally or whether they set off some other mechanism that causes allergic-like reactions.
One theory is that people allergic to sulfites have a genetic abnormality that hinders the body’s breakdown of these chemicals. However, Dr. Susan Tarlo, a respiratory physician at Toronto’s University Health Network and a specialist in lung disease and allergic response, says her extensive research does not confirm that theory. Another theory links sulfite sensitivity to a lack of vitamin B12, but this is not conclusive.
Sulfite’s Effects on the Body
In the lab, sulfites are considered anti-microbial and anti-oxident in drugs as well as a preservative in many preperations. In addition to these effects, sulfites oxidize to sulfite radicals, initiating lipid peroxidation.
A study done on rats to investigate the effects of long-term exposure of sulfite. A group of rats were stressed with sulfites versus a control for 21 days. The study had proven that sulfite in the environment decreased enzyme activities and enhances brain lipid peroxidation because of the ingested sulfites.
Diagnosing a Sulfite Allergy
If you drink a glass of wine or eat packaged dried fruit and have trouble breathing afterward, then you can suspect that you have a sulfite allergy/sensitivity. You should see an allergist to confirm this sensitivity and find out what is causing your symptoms. The only safe way would be to undergo an oral challenge in a hospital setting. Doctors will give you a sample of something with sulfites and monitor your bodily response.
Research done in Canada may suggest that there has been a rise in prevalence of sulfite allergy over the past few decades. The incidence may simply be the result of better diagnosis and awareness of sulfite allergy. In fact, studies show that awareness of sulfite reactions has declines since improved food labeling and the ban of spraying sulfites on raw fruits and vegetables.
Symptoms of Sulfite Allergy
Sulfites are common in processed foods, condiments and alcoholic beverages. They occur naturally in wine during fermentation and many winemakers add them to help the process along. For the past twenty years, the United States Food and Drug Administration has required winemakers to display the warning “contains sulfites” if levels exceed a certain threshold. Many companies voluntarily add the label to their products as well.
Symptoms of allergic reaction to sulfites include:
- Swelling of mouth and lips
- Wheezing or trouble breathing
- Asthma attack
Management and Treatment of Sulfite Allergies
The best way to treat the symptoms of a sulfite allergy is to know what to avoid. Lists of food groups are generally not helpful when determining what to avoid, which can be difficult. For instance, many lists will warn you that canned goods will contain sulfites, but not all of them do. You just need to take off the blindfold and examine the ingredients list.
Foods that may contain sulfites (partial list):
- Alcoholic beverages
- Bakery items: Breads with dough conditioners, cookies, crackers, etc.
- Beverages containing sugar or corn syrup, dried citrus fruit beverages, bottled fruit drinks
- Condiments: Horseradish, relishes, pickles, olives, wine vinegar
- Dairy: Processed cheese
- Dried fruits, herbs and trail mixes
- Fruit: Grapes, dried fruit, canned fruit and juice, cherries, glazed fruit
- Gelatins, fillings: Pectin and jelling
- Grains: Corn starch, modified food starch, gravy, breading, batter
- Hard candy
- Jams and jelly
- Shredded coconut
- Plant Protein: Soy protein including tofu and infant formula
- Snacks: filled crackers, dried fruit snacks, trail mix, chips
- Sugar: Brown, white, powdered and raw
- Vegetables: Juice, canned, pickled, frozen
Another way to avoid sulfites is to neutralize them before eating them. Hydrogen peroxide is a strong oxidant that can convert sulfite ions to a safer sulfate form, which is necessary in the body. If you suspect that a fresh fruit or vegetable is contaminated with surface sulfites, you can soak it for a few minutes in hydrogen peroxide and then rinse it off before eating. Soaking or washing the fruit will not help very much.
If your sulfate allergy hinders the productivity of your everyday life, then an over-the-counter antihistamine may ease and shorten your symptoms for a short period. If you accidently consume something with sulfites, you can take one of these drugs to block the histamine response. However, the inflammation will still be doing damage to your body.
Another possible way to treat a sulfite allergy is to examine your diet for a vitamin B12 deficiency. In a small trial with asthmatics, B12 increased the sulfite threshold somewhat and reduced the number of attacks. The amount of B12 taken was around 1000 micrograms per day. This is worth a try because the vitamin is very inexpensive as a supplement and available in a variety of natural foods.(3)
It’s important to realize that sulfite allergy is not the same as “sulfa” allergy, a reaction to additives put in prescription drugs. If you or your child has discovered that they have symptoms directly correlated with consuming sulfites, then you will want to avoid all traces of sulfites in your diet.
Sulfite allergy is a special case in which the reactions are not associated with a protein, but rather a chemical compound. Researchers are recently discovering the true causes of sulfite allergy and the best lead they have is a vitamin B12 deficiency. If symptoms are hindering your daily productivity, then it would be wise to have an emergency antihistamine available if you come in contact with sulfites.