Not taking sides here... honest..cos can't better the answer given but from Wiki
Food intolerance or non-allergic food hypersensitivity is a term used widely for varied physiological responses associated with a particular food, or compound found in a range of foods.
Food intolerance is a detrimental reaction, often delayed, to a food, beverage, food additive, or compound found in foods that produces symptoms in one or more body organs and systems, but it is not a true food allergy. A true food allergy requires the presence of immune mechanisms (as for instance Immunoglobin E - IgE antibodies) against the food, and a food intolerance does not