Soy in wheat--contamination levels and food allergy risk assessment.

In the United States, packaged food ingredients derived from allergenic sources must be clearly labeled. However, no requirement exists to declare the presence of residues of raw agricultural commodities due to agricultural commodity comingling. Clinical reports of allergic reactions to undeclared soy in wheat-based products do not exist suggesting that a rather low degree of risk is posed by wheat-based products that are comingled with soy. Detectable soybean residues (>2.5 ppm soy flour) were found in 62.8% of commercially available wheat flours at concentrations of 3-443 ppm soy flour (1.6-236 ppm soy protein). Conservative probabilistic risk assessments predict a risk of allergic reaction among the most sensitive soy-allergic individuals of 2.8±2.0 per 1000 soy-allergic user eating occasions of foods containing wheat flour. However, the predicted reactions occur at exposure levels below the lowest eliciting dose observed to provoke objective reactions in clinical oral soy challenges. Given this low level of predicted risk and the lack of evidence for allergic reactions among soy-allergic consumers to wheat-based products, the avoidance of wheat-based products by soy-allergic consumers does not appear to be necessary.