Adverse reactions and possible causes
Sulphites are compounds that contain the sulfite ion SO 32 . Sulphites and sulphiting agents are widely used as additives in the food and pharmaceutical industries, thanks to their preservative, antioxidant and antimicrobial activity.
Although these additives are considered to be safe for the majority of people, they have been reported to induce a range of adverse clinical effects in sensitive individuals, involving skin, gastrointestinal tract and the airways.
Sulphites can be found in a great variety of industrial products:
- Food and drink: for the majority of people exposure to sulphites occurs as a result of consumption of many food and drink to which sulphites have been added, mainly for the purpose of preservation; moreover, sulphites are used to prevent the browning of foods, as bleaching agents as dough conditioning agents, to prevent excess alkalinity, as food processing aids, colour stabilizers and antioxidant. Foods containing sulphites include dried fruit and vegetables, fresh salads and meat, and they are widely added in wine – white wine in particular – and beer.(Sulfite in food: uses, analytical methods, residues, fate, exposure assessment, metabolism, toxicity and hypersensitivity,1986.)
|| Bottled soft drinks and fruit juice, cordials, cider, beer, wine (including sparkling wine)
| Other liquids
|| Commercial preparations of lemon and lime juice, vinegar, grape juice
|| Dried apricots, fruit bars
| Commercial foods
|| Dried potatoes, gravies, sauces and fruit toppings, maraschino cherries, pickled onions, sauerkraut, pickles, maple syrup, jams, jellies, biscuits, bread, pie and pizza dough
|| Delicatessen meats, mince meat, sausages
| Other foods
|| Gelatin, coconut, salads and fruit salads, crustaceans
|| hair colours and bleaches, home permanent solutions, skin fading/lighteners, false tan lotions, anti-ageing creams and moisturisers, facial cleansers, around-eye creams, body washes/cleansers, hair sprays, perfumes, blush, bronzers/highlighters
|| Topical anti-fungal and corticosteroid creams and ointments (e.g. Trimovate®, Timodine®, Aureocort®, Aureomycin®, Nizoral®, Nystatin®, Lustra®, Psoradrate®), adrenaline, isoprenaline, isoproterenol, isoetharine, phenylephrine, dexamethasone and injectable corticosteroids, dopamine, local anaesthetics, propofol, aminoglycoside antibiotics, metoclopramide, doxycycline and vitamin B complex
The average person consumes 2 to 3 mg of sulphites per day. Wine and beer drinkers consume up to 10 mg/die and those who eat in restaurants (restaurant foods are considered to contain the highest quantity) may ingest up to150 mg/die. (Adverse reactions to sulfites,1985)
In the early 1980s there were numerous reports suggesting that ingestion of sulphites by susceptible individuals was the cause of severe adverse reaction; as a consequence of this, in 1986, the U.S. Food and Drug Administration banned the use of sulfites as preservatives on foods intended to be eaten fresh (such as salad ingredients) and foods in which the use of sulphite was permitted, sulphites concentrations >10 ppm had to be declared on the label.
In Europe a similar law came into force in 2005. (Wikipedia)
E numbers (codes for chemicals which can be used as food additives) for sulphites are:
|| Sulfur dioxide
|| Potassium metabisulphite
|| Sodium sulphite
|| Potassium sulphite
|| Sodium bisulphite
|| Calcium sulphite
|| Sodium metabisulphite
|| Calcium hydrogen sulphite
Degradation by Sulfite Oxidase
Sulfite oxidase is a mitochondrial enzyme high expressed in the liver, kidneys and heart.
It catalyzes the oxidation of sulfite to sulfate and the reaction takes place at the molybdenum center of the protein.
A possible explanation for sulfite sensitivity might be the widespread molybdenum deficiency found in a majority of patients. Many have no detectable blood molybdenum and most have levels below 5 ppb (normal 10 to 100 ppb).
Part of the patients’ symptomatology is considered due to high accumulated toxic sulfite and insufficient sulfate, and low levels of molybdenum may explain the defect in the transformation of sulfite to sulfate, leading to sulfite sensitivity.
It has been demonstrated that a molybdenum deficient diet would result in a sulfur handling defect at the level of transformation of sulfite to sulfate. Molybdenum is contained in legumes such as soybeans, navy beans and lentils. This is gassy peasant food, so in developed countries these foods are normally avoided.
Supplements of molybdenum could be useful to prevent sulfite effects,and in addition, it would also be prudent for the sulfite-sensitive individual, or for that matter for any individual exposed to undue quantities in foods, drugs or urban smog, to take additional supplements of vitamin C and thiamine, both known to be depleted by excessive sulfiting agents. Perhaps some pantothenic acid, found to have a significant protective action against sulfur dioxide poisoning would also be helpful.(Sulfite Sensitivity – Unrecognized Threat: Is Molybdenum Deficiency the Cause?,1984)
The types of reactions and the concentration of sulphites that provoke reactions may vary widely with different forms of exposure.
Symptoms which have been reported as commonly experienced by sulfite-sensitve individuals include: wheezing, labored breathing, chest-tightness, cough, faintness, extreme shortness of breath, respiratory arrest, loss of consciousness, blue discoloration of skin, flushing, angioedema, hives, laryngeal edema, hypotension, generalized itching, contact dermatitis, episodic swelling of hands, feet and eye areas, mood changes, clammy skin, abdominal cramps, nausea, diarrhea and anaphylactic shock. (Sulfite Sensitivity – Unrecognized Threat: Is Molybdenum Deficiency the Cause?,1984)
However, the vast majority of reports described the triggering of bronchoconstriction in asthmatic patients: sulphite induced asthmatic symptoms range from mild in some individuals to very severe in others, and in some individuals these reactions can be life threatening. It has been estimated that 3-10% of asthmatics experience sulfite-related symptoms.
In addition to episodic and acute symptoms, sulphites may also contribute to chronic skin and respiratory affections.
Anaphylaxis has been described, but is very rare: treatment of anaphylaxis in patients who are sensitive to sulphite poses a number of questions in that administration of adrenaline is regarded as the primary treatment for anaphylaxis, but most of the commercially available preparations of adrenaline contain metabisulphite. However, even in patients with serious sulphite sensitivity, the benefit from adrenaline is considered to outweigh the risk of sulphite exposure associated with use of adrenaline in an emergency. (Adverse reaction to sulphite additives,2012)
- Inhalation of SO2
Sulfur dioxide gas is an irritant, and so reflex contraction of the airways from inhaling sulfur dioxide is a possible explanation; the mechanism may explain the rapid onset of symptoms when drinking liquids like beer or wine, when SO2 is ihalated during the swallowing process.
Some people have positive skin allergy tests to sulphites, indicating an Ig-E mediated allergy: the symptoms are due to the release of histamine and other mediators as a consequence of mast cell degranulation.
- Sulfite oxidase
Some people with asthma who react to sulphites have a partial deficiency of the enzyme sulfite oxidase which helps to break down sulphur dioxide.
- Alice Ferguglia