Dietary protein intolerance

This chapter discusses dietary protein intolerance. Clinical food intolerance has many causes and many manifestations, including psychological aversion to the sight, smell, or taste of food as well as psychological intolerance to one or more of the many constituents of food. Dietary protein intolerance is the clinical syndrome resulting from the sensitization of an individual to one or more proteins that have been absorbed via a permeable mucosa in the small intestine. Intolerance to various food proteins, especially to cows' milk, has been recognized in children for many years. Such food intolerance may be the result of a variety of causes—for example, a congenital digestive enzyme defect such as sucrase–isomaltase deficiency or an acquired lactase deficiency secondary to small-intestinal mucosal damage, which in turn can be the result of a food allergy. The incidence of gastrointestinal food allergy diseases is greatest in the first few months and years of an infant's life and decreases with age. The acute syndrome is usually characterized by the sudden onset of vomiting, after cows' milk ingestion, occasionally followed by pallor and a shock-like state; however, acute anaphylaxis is rare. Acute abdominal pain seems to be a particular feature of fish hypersensitivity, while peanuts often produce immediate reactions in the oral mucosa as well as abdominal pain.