Sulfite-induced asthma

The mechanism of sulfite-induced asthma is not well-understood. Reactions to sulfited foods probably depend on the sulfite residue level in the food, the sensitivity threshold of the individual, the type of food consumed, and whether sulfite exists in the free (more toxic) form or combined (less toxic) form. The toxicology of sulfites has been reviewed by Madhavi and Salunkhe (1995). Sulfite sensitivity is not a true allergic reaction (Taylor et al., 1988). The FDA initially estimated that more than 1 million Americans are sensitive to sulfites, but more recent estimates lowered the number of asthmatics who may be sulfite sensitive to 80,000-100,000 (Bush et al., 1986). 

Food intolerances are mostly caused by substances other than proteins and affect a limited number of individuals. Examples include sulfite-induced asthma, lactose intolerance, MSG-induced headache and flushing, etc., yet these substances are only associated with these symptoms and remain unproven as causative agents. Significant levels of these non-flavor ingredients are typically required to elicit this type of reaction, and there is no evidence that flavoring substances are involved (Taylor and Dormedy, 1998). 

Asthma can be induced by chemicals that are ingested or dermally applied as well as inhaled chemicals. Sulfites in wine, salads, other foods, and some medications are known to induce asthma when ingested, I41-43 ... 

Vally H, Thompson PJ (2001). Role of sulfite additives in wine induced asthma single dose and cumulative dose studies. Thorax., 56 763-769. 

Asthma can be induced by chemicals that are ingested or dermally applied as well as inhaled chemicals. Sulfites in wine, salads, other foods, and some medications are known to induce asthma when ingested [7, 45 7] and many chemicals, including isocyanates and anhydrides, have been shown to induce asthma following dermal exposure [48, 49]. The discussion in this section, however, will be limited to inhaled chemical mixtures as causative agents for asthma. 

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