A food intolerance is a food sensitivity that is not an allergic, immune-system mediated, reaction. Examples inclode lactose intolerance.
Food intolerances typically stem from gastrointestinal issues, such as a lack of a particular enzyme responsible for digesting a component of the food.
With food intolerances, the individual response typically requires that a significant quantity of the poorly tolerated food be consumed. This is distinct from allergies where trace amounts of allergen can induce a response.