Using an optimized and validated ELISA method, we performed a serum test for assaying the binding capacity of serum IgG to proteins extracted from approx. 160 different foods to investigate the reactivity of specific IgG antibodies in the Italian population composed of 6,879 subjects (4,551 females and 2,328 males). 44 antigens showed an IgG response greater than 10% and only 14 aliments had an elevated reactivity greater than 20%, in particular, milk, from cow and goat, and several milk derivatives, along with egg albumen and yeasts. The IgG response to the high reactive food antigens depending on the age of the 6880 subjects was also analyzed. We demonstrated a high IgG response in a very large subject group to milk and milk derivatives, and egg albumin antigens, and we conclude that the validated ELISA test may be applied for the serum/plasma IgG antibody level determination as a useful indicator of adverse reactions to food and food hypersensitivity.