In light of my recent posting (Elimination Diets - Are They Healing or Compounding the Problem?) , I think an important clarification is needed in the terminology of allergies and intolerances. So here are just a few definitions and specifications:
An allergy and an intolerance are separate concepts, though they are frequently used interchangeably. An allergy induces the immune system to respond releasing histamine, antibodies and other chemicals leading to symptoms such as breathing difficulty, hives, rash, itching, coughing, wheezing, sneezing, swelling, anaphylaxis—all responses specific to histamine and the immune system. An allergy is often the result of the immune system overreacting (and not in the hysterical, emotional sense:) to substances it believes are harmful.
Response to an intolerance however does not involve the immune system and is not inherently life-threatening. Upset stomach, diarrhea, vomiting, nausea, gas, bloating, fatigue, headaches, cramps are signs of an intolerance. For one to have a true food allergy, it would necessitate the presence of allergic signs such as those mentioned above. Gluten, dairy and MSG intolerances are commonly labeled under “allergy,” but are not in and of themselves allergies. Unless hives, rash, swelling, or difficulty breathing are present, an allergy does not exist. Most often, intolerances involve a lack of necessary enzymes.
In the case of a more significant form of gluten intolerance which is celiac sprue or celiac disease, the immune system may get involved but in a different way. The individual’s immune system actually turns on itself (autoimmune response largely involving T cells) and causes damage to gastrointestinal tissues. The issue of whether or not celiac disease is specifically a histamine response is under debate.
An adverse reaction is similar to the mechanism of an intolerance. It involves a response to a stimulus that is unwanted or unexpected, such as diarrhea, nausea, vomiting, headache, etc. Adverse reactions are a more general way of describing a response to a stimulus. Strictly speaking, they are defined differently than allergic reaction. When your health history is being taken, and your provider asks whether you have any allergies, he or she usually asks what is your response to that substance. If it is hives, swelling, etc most practitioners note it as an allergic reaction. If it is diarrhea, nausea and vomiting, etc, it is usually indicated as an adverse reaction.
A sensitivity can exist without necessitating the existence of a specific intolerance or allergy. For instance, you put on a pair of rubber latex gloves. Later when you take them off, you notice that your hands are a bit reddened and are itchy, but it clears up on its own after a while. Though at some point this could possibly develop into a allergy, it is simply a sensitivity.
Definition of Adverse Reactions to Food