Summary

See also, Barley

Clinical Relevance

IgE-mediated reactions

Malt may uncommonly induce symptoms of food allergy in sensitised individuals, including Baker's asthma, urticaria, facial itching, Quincke edema, systemic symptoms and anaphylaxis. Symptoms usually occurred after the consumption of Malt-containing chocolate drinks and Malt-containing snack products.

A 21-year-old atopic woman developed urticaria, angioedema of the face, and wheezy dyspnea shortly after drinking beer and eating a Maize-based snack. Skin-specific IgE was detected, and specific IgE measurements with beer, Barley, Malt, Wheat, Maize, Rye, Rice, and Oat flour were positive. This patient developed type I hypersensitivity to Barley/Malt and Maize. Although she also showed IgE reactivity to Wheat and other cereals, no symptoms were elicited upon ingestion of these cereals, probably indicating latent sensitisation to them. Urticaria as a result of drinking beer has been reported in three individuals.

Two cases of severe systemic reactions due to beer ingestion have been reported: 1 of anaphylaxis and 1 of generalised urticaria and angioedema. Special investigation, in particular skin- and serum-specific IgE determination, showed that Barley was the specific ingredient responsible for the observed allergic reactions to beer.

Other reactions

Barley grain contains a protein that cross-reacts with Wheat gluten in those prone to coeliac disease. Usually, these patients are advised to avoid Malt. At present, there is no proof that Barley Malt provokes coeliac symptoms, but it may be prudent for these patients to avoid Malt because of the possible gluten-like residues.

Cross-Reactivity

An extensive cross-reactivity among the different individual species of the genus of Barley could be expected, and this may result in cross-reactivity if the protein remains intact in the malting process.

In a patient who developed allergic symptoms shortly after drinking beer and eating a Maize-based snack, inhibition assays showed that the Malt extract was able to inhibit most of the IgE-binding proteins in Wheat and Maize extracts, whereas Maize did not produce significant inhibition to Barley and Malt extracts. This patient displayed immediate hypersensitivity to Barley/Malt and Maize).