Clinical characteristics of soybean allergy in Europe: A double-blind, placebo-controlled food challenge study

Background

Soybean is a relevant allergenic food, but little is known about individual threshold doses in soy allergy.

Objective

We sought to determine the clinical characteristics of soy allergy in Europe, including a dose-response curve.

Methods

Patients with a history of soy allergy underwent a titrated, double-blind, placebo-controlled food challenge. A statistical model was used to calculate the risk of allergic consumers to experience an allergic reaction to soy. Sera were analyzed for specific IgE to soy, peanut, Bet v 1, and Gly m 4.

Results

All patients but one responded primarily with subjective symptoms to the challenge followed by objective symptoms in 11 subjects, ranging from rhinitis up to a decrease in blood pressure. Cumulative threshold doses for allergic reactions ranged from 10 mg to 50 g for subjective symptoms and from 454 mg to 50 g for objective symptoms. The pattern of IgE reactivity against proteins with molecular weights of between approximately 10 and 70 kd was highly individual among the patients and did not correlate with the severity of symptoms.

Conclusions

When data are fitted by using a normal distribution statistical model, they predict that 1% of patients with soy allergy would react subjectively and objectively with 0.21 and 37.2 mg of soy protein, respectively.

Clinical implications

Both the clinical and immunologic basis of soy allergy in Europe are highly complex, which affects the diagnosis of soy allergy and the advice given to patients with soy allergy in regard to risk management.

Key words: Food allergy, double-blind, placebo-controlled food challenge, threshold dose, soy allergy, diagnosis, soy allergens

Abbreviations used: DBPCFC, Double-blind, placebo-controlled food challenge, EAACI, European Academy of Allergy and Clinical Immunology, LOAEL, Lowest observed adverse effect level, NOAEL, No observed adverse effect level, OAS, Oral allergy syndrome, SPT, Skin prick test