Host: What is the difference between food allergy and intolerance?
Robert B. Gravani: A true food allergy really involves the immune system, it's a immune system response to a protein. Intolerance does not involve the immune system and a good example of this would lactose intolerance. About 25% of the U.
S. population is lactose intolerant, that is they lack an enzyme called lactase that allows them to digest if you will the milk sugar lactose and those who cannot digest usually have lots of rumbling and gas and a feeling of loading in diarrhea when they consume dairy products but it does involve the immune system.