Sulfites are commonly used in the processing and storage of various foods and drinks. In the U.S., they were finally banned for use on produce in 1986. At that time the FDA also required other beverages containing sulfites, such as wine, beer and dried fruit to have warning labels.
Sulfites are sulfur-based preservatives that are used to prevent or reduce discoloration of light-colored fruits and vegetables, prevent black spots on shrimp and lobster, inhibit the growth of microorganisms in fermented foods such as wine, condition dough, and maintain the stability and potency of certain medications. Sulfites can also be used to bleach food starches, to prevent rust and scale in 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 used on vegetables to keep them "fresh" longer.
A person can develop sulfite sensitivity at any point in life.
Products That Contain Sulfites
Sulfites can occur naturally in foods or are added to enhance food products. Sulfites are produced naturally during the fermentation of wine. There is a variety of foods that contain sulfites including baked goods, soup mixes, jams, canned vegetables, pickled foods, gravies, dried fruit, potato chips, trail mix, beer, wine, vegetable juices, bottled lemon juice, bottled lime juice, tea, condiments, molasses, fresh or frozen shrimp, guacamole, maraschino cherries, and dehydrated, pre-cut, or peeled potatoes.
There are six names used for sulfites: sulfur dioxide, sodium sulfite, sodium bisulfite, potassium bisulfite, sodium metabisulfite, and potassium metabisulfite. Sulfites, bisulfites and metabisulfites are all dry chemical forms of the gas, sulfur dioxide.
Foods that may contain sulfites (partial list):
The FDA estimates that 1% of people are sulfite-sensitive and 5% of those also suffer from asthma.
It appears that sulfite sensitivity may be caused by a relative deficiency of the enzyme sulfite oxidase which breaks down sulfites and requires molybdenum as a cofactor. As with lactase deficiency, this is a metabolic problem and not an allergic one.
Asthma, nasal and sinus congestion, rhinitis, postnasal drip, frontal headache and bronchospasm can be triggered by sulfites.
Sulfites can be measured in the urine, and used as a means of monitoring symptom correlation with treatments such as molybdenum.
Serum copper should be checked because high levels can drive molybdenum levels down.
Molybdenum deficiency may be responsible for sulfite sensitivity since it is a cofactor for sulfite oxidase. Sulfite oxidase catalyzes the last step (sulfites to sulfates) in the breakdown of sulfur amino acids. Sulfite oxidase in this way helps to detoxify sulfurs in the body – particularly sulfites – which are used to preserve food. It is possible that adequate tissue levels of molybdenum keep the sulfite oxidase activity levels high enough to counteract this chemical and reduce potential symptoms; molybdenum deficiency may be a factor in those people who are more sensitive to sulfites.
Supplementation with B12 may reduce sulfite sensitivity. In one study the oxidative action of vitamin B12 was able to block a sulfite-induced bronchospasm in 4 out of 5 asthmatic children. In another study, the following conditions responded to B12 use: Intractable asthma – 18 out of 20 patients improved; Chronic urticaria – 9⁄10 improved; Chronic contact dermatitis – 6⁄6 improved; Atopic dermatitis – 1⁄10 greatly improved and 5⁄10 moderately improved with 1000mcg IM once weekly for 4 weeks. [J Allergy 2: 183- 5, 1951]
Blood levels of B12 indicate that sublingual B12 becomes available as early as 15 minutes after administration and is still elevated at 24 hours, suggesting that a once-daily dose of 2000-4000mcg would be an effective prophylactic measure. [Bhat N.K. – Presentation at the 43rd Annual Meeting, American Academy of Allergy and Immunology, 1987]
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