Allergy to food additives.

PURPOSE OF REVIEW: To provide an update of the studies concerning the diagnosis and management of food additives allergy. RECENT FINDINGS: Additives improve specific characteristics of food products, but they may induce allergic even life-threatening reactions. Physical examination and medical history are basic to assess specific in-vivo and in-vitro tests. The only treatment for allergic patients consists in avoiding the food containing culprit additives. High-risk patients should be able to recognize severe reactions and self-manage them. SUMMARY: The prevalence of adverse reactions to food additives is low, and it may depend on comorbidities, like asthma or chronic idiopathic urticaria. Food labels may help the correct identification of ingredients. Natural additives like spices should cause immediate reactions because of a pollen-sensitization or panallargen proteins presence. Additive-free diets may help the patient care, but the authors suggest assessing an oral food challenge with the culprit substance if there are no contraindications.

Monosodium glutamate 'allergy': menace or myth?

Monosodium glutamate (MSG) is a salt form of a non-essential amino acid commonly used as a food additive for its unique flavour enhancing qualities. Since the first description of the 'Monosodium glutamate symptom complex', originally described in 1968 as the 'Chinese restaurant syndrome', a number of anecdotal reports and small clinical studies of variable quality have attributed a variety of symptoms to the dietary ingestion of MSG. Descriptions of MSG-induced asthma, urticaria, angio-oedema, and rhinitis have prompted some to suggest that MSG should be an aetiologic consideration in patients presenting with these conditions. This review prevents a critical review of the available literature related to the possible role of MSG in the so-called 'Chinese restaurant syndrome' and in eliciting asthmatic bronchospasm, urticaria, angio-oedema, and rhinitis. Despite concerns raised by early reports, decades of research have failed to demonstrate a clear and consistent relationship between MSG ingestion and the development of these conditions.

Monosodium glutamate sensitivity in asthma.

BACKGROUND: Questions have been raised since the early 1980s about monosodium glutamate (MSG) and provocation of asthma. Because MSG is widely available as a chemical in both natural foods and as an additive in many prepared foods, the need to define the relationship of MSG to asthma is of great importance. OBJECTIVE: The purpose of this study was to determine whether MSG ingestion induces asthma attacks in asthmatic subjects. METHODS: With single-blind, placebo-controlled screening challenges, 100 subjects with asthma (30 subjects with a history of Oriental restaurant asthma attacks; 70 subjects with a negative history) were challenged with 2.5 g of MSG. A total of 78 patients were proved to have aspirin-sensitive asthma. RESULTS: No patient had a significant fall in FEV(1 ) value or the development of asthma symptoms during the MSG challenge. The mean change in FEV(1 ) with MSG challenge was no different from that of placebo challenge. Subjects with an MSG-positive history showed no significant percent decrease in FEV(1 ) values after placebo challenges compared with MSG 2.5 g oral challenge (P =.28). In the group with an MSG-negative history, there was no statistical difference in the change in lowest FEV(1 ) values between the placebo and MSG challenges (P =.44). The exact 1-sided 95% confidence interval (CI) for the probability of MSG sensitivity in individuals with aspirin-sensitive asthma (negative history) is 0% to 0.04%. When combined with previous studies that did not demonstrate MSG-provoked asthma, the 95% CI is 0% to 0.03%. For patients with an MSG-positive history, the exact 1-sided 95% CI for the probability of MSG sensitivity in this study was 0% to 0.07%, which is somewhat wider because of the smaller sample size. CONCLUSIONS: MSG challenges in subjects with and without a perceived sensitivity to MSG failed to induce signs or symptoms of asthma. Therefore in view of the poorly conducted studies that proposed that MSG induced asthma and the subsequent studies that failed to confirm those findings, it is important to maintain a healthy skepticism about the existence of MSG sensitivity in individuals with asthma.

The effects of monosodium glutamate in adults with asthma who perceive themselves to be monosodium glutamate-intolerant.

BACKGROUND: Many previous clinical studies of food-induced asthma suffer from inadequate baseline or control data. A statistically valid, randomized, double-blind, placebo-controlled, monosodium glutamate (MSG)-challenge protocol was developed for identifying early and late asthmatic reactions in an individual. OBJECTIVE: We sought to determine whether MSG would induce bronchoconstriction in a group of adults with asthma who perceived that they were MSG sensitive. METHODS: Twelve subjects (seven women, mean age 35.3 years) with clinically documented asthma and a perception of MSG-induced asthma were recruited. FEV1 and peak expiratory flow data were obtained for 3 whole control days, as well as time-matched data for 3 separate challenge days (1 gm MSG, 5 gm MSG, and 5 gm lactose [placebo]). Opaque capsule challenges were given as a single dose in the morning after an overnight fast. Subjects complied with an elimination diet throughout the study. Nonspecific bronchial hyperresponsiveness was measured at baseline, after the control days, and at the conclusion of the challenges. Venous blood samples were taken at baseline and on each challenge day to determine soluble inflammatory marker (eosinophil cationic protein and tryptase) activity. RESULTS: No immediate or definite late asthmatic reactions occurred. One subject's FEV1 declined more than 15% on MSG challenge, but 95% confidence limits for the control-day spirometry showed that this decline was within her daily variation, hence the challenge was deemed to be negative. No significant changes in bronchial hyperresponsiveness or soluble inflammatory markers were found. CONCLUSIONS: MSG-induced asthma was not demonstrated in this study. This study highlighted the importance of adequate baseline and control data and indicated that such a rigorous protocol for individual assessment is feasible.