Special Topics
Allergies to Food Additives
Over the years, many case reports have blamed food dyes, preservatives, and additives, such as aspartame and monosodlum glutamate (MSG), for a variety of allergic or pseudoallergic reactions. Reactions range from acute or chronic urticaria and induction or exacerbation of bronchial asthma to migraine headaches and behavioral disorders, such as hyperactivity and attention deficit disorders. Larger-scale trials and DBPCFC have not substantiated most of these associations.
MSG was reported to cause the “Chinese restaurant syndrome” rarely in individuals consuming large amounts of MSG. Symptoms start 30 mins after ingestion and manifest with anxiety, headache, sweating, flushing, palpitation, tightness, a burning sensation in the face and chest, and a crawling sensation of the akin. The condition is self-limited and subsides over 1-2 hrs.
Food preservatives, such as benzoate, butylated hydroxyzole, and butylated hydrox-ytoluene, were not associated with APR in well-designed studies. Sulfites, on the other hand, were found to exacerbate asthma in a small percentage of asthmatics ( In European studies, artificial food colors have been blamed for S 15% of chronic urticaria cases, whereas in the Unites States this high percentage has never been substantiated. Tartrazine (food dye yelZow 5) has been reported to cross-react with aspirin in aspirin-sensitive asthmatics, a finding that could not be validated in DBPCFC in aspirin-sensitive individuals. However, yellow 5 is implicated in rare cases of asthma independent of aspirin.
The sugar substitute aspartame has been implicated in very few cases of chronic urticaria. A multi-center study using DBPCFC was unable to confirm this association. Sugar allergy, a term coined in the mid-1980s, was believed to contribute to attention deficit disorder and juvenile delinquency behavior, an assumption completely refuted by controlled studies.
Key Points
More patients believe they have food allergies than what could be found using blinded food challenges.
Pood “allergy” is a subset of a larger group of adverse food reactions (AFRs). AFRs include idiosyncratic, toxic, and pharmacologic, as well as allergic, reactions to food.
Young children have more food allergies than adults but tend to outgrow their allergies, especially after a period of strict elimination.
Milk, egg, wheat, soybean, and peanut cause more than 90% of food allergies in children.
Oral allergy syndrome results from cross-reactivity of food allergen with certain pollen aeroallergens.
Detailed history and skin tests are the most valuable diagnostic tools of food allergies.
There is no role for Immunotherapy in the treatment of food allergy. Patient (and parent) education and anaphylaxls kits are the most powerful life-saving measures in severe food allergy.
