It is estimated around 20% of the population has adverse reactions to foods. The symptoms can range from mild discomfort to life threatening, and can be associated with a variety of diseases including asthma, eczema, ear infections, mood and behavior problems, colitis, migraines, and more. The cause of these abnormal food reactions vary from true "IgE-mediated" allergies to "IgG-mediated" food sensitivities, and can also be from a lack of specific enzymes needed to digest a particular food.
Read more: About Food Allergies and Sensitivities