Defining and diagnosing food intolerance can be problematic due to the range of terms used by lay and scientific communities including "adverse reaction to food", "food allergy" and "food intolerance". Prevalence in the community also range from 2 percent to 33 percent depending on the terms used. Nonetheless, evidence suggests that food intolerance, a non-immunological reaction, is becoming increasingly common, with symptoms including bowel and stomach problems, headaches and skin problems. For example, Halken (1997) points out that approximately 50 to 70 percent of children with a food intolerance demonstrate skin problems, 50 to 60 percent gastrointestinal symptoms and 20 to 30 percent respiratory symptoms. Among young children with food intolerance the majority have two or more symptoms, with symptoms occurring in two or more organ systems. Halken (1997) suggests that only one third of children can be diagnosed with a food intolerance by way of a controlled elimination/challenge diet/procedure. Despite this fact, the prognosis of food intolerance during childhood is good, particularly in children under the age of 3. There is evidence to suggest that a prognosis of cow's milk protein intolerance in infancy can be reversed, with a recovery rate of approximately 45 to 56 percent at 1 year, 60 to 77 percent at 2 years, and 71 to 87 percent at 3 years (Halken, 1997).
Halken, S. 1997. Clinical symptoms of food allergy/intolerance in children. Environmental Toxicology and Pharmacology, 4, 175-178.