An allergy is a false alarm triggered by the body's immune system as a response to harmless substances in our environment, e.g. pollen, or protein in food.
Phenylketonuria (PKU) is a rare metabolic disorder that affects the way the body breaks down protein. This is a genetic disorder. Untreated children are severely impaired in their motor and especially mental development.
The term food intolerance refers to disorders and abnormalities in nutrient absorption which generally leads to malnutrition. Common malabsorption problems like celiac disease are commonly seen in children other than adults.
It is the most common carbohydrate intolerance. It is a condition in which patients can't tolerate milk and milk products.