Association between Food-Specific Immunoglobulin G₄ Antibodies in Adults with Self-Reported Signs and Symptoms Attributed to Adverse Reactions to Foodstuffs

Signs and symptoms attributed to adverse reactions to foodstuffs (ARFS) need tools for research and evaluation in clinical practice. The objectives of this study were (a) to evaluate the most frequent self-reported signs and symptoms attributed to ARFS in Spanish adults, (b) to determine the prevalence of food-specific IgG₄ antibody reactions (AbRs), and (c) to investigate the association between self-reported ARFS symptomatology and food-specific IgG₄ AbRs. Food-specific IgG₄ AbRs against 57 common food and beverages (AESKUCARE-T2FA^® in vitro point-of-care test kit, Aesku.Diagnostics GmbH, Germany) were determined in capillary blood samples of 205 volunteers living in the Region of Madrid (Spain). The most frequent self-reported signs and symptoms were related to skin (43%), digestive (41%), and nervous system (NS, 33%) problems. The prevalence of food-specific IgG₄ AbRs was cow's milk (73%), sheep's milk (70%), casein (66%), and goat's milk (56.10%). Positive IgG₄ AbRs against tomato had a profile consisting of 3/4 of skin problems, more than half of digestive, and 2/5 of NS self-reported signs and symptoms. In conclusion, at least 1/3 of the studied sample reported skin, digestive, and NS signs and symptoms. The most frequent food-specific IgG₄ AbRs were related to dairy. Skin problems were more frequent in positive tomato IgG₄ AbRs.