Food allergy, food sensitivity, or food intolerance are all terms that people use to describe adverse reactions to food.  While these terms are often used interchangeably, technically they describe three different types of reactions to food that have a negative impact on physical and mental health.

True Food Allergy -  Also known as a type- I hypersensitivity ( IgE or immunoglobulin E) is an immediate immune response to a foreign substance that has entered the body.  True Food Allergies can cause serious symptoms such as difficulty breathing, hives, swelling, and anaphylactic shock. It's estimated that true food allergies only affect about 4% of the population. If you have an IgE allergy, you probably already know it because of the severe symptoms. Examples of most common allergens include peanuts, nuts, milk, eggs, shellfish, wheat, and soy.  

Food Sensitivities – This takes place when your body has a less severe non-IgE immune response to a specific food. Offending foods are recognized by the body and prompt an immune response that releases IgG antibodies and/or a myriad of biochemical mediators into the bloodstream. This can cause inflammation of the gut or joints. It is estimated that over 80 percent of the population have undiagnosed food sensitivities. Symptoms include weight gain, joint soreness, fatigue, bloating, mood disorders, skin irritations, digestive disorders, IBS, dark circles under the eyes, headache (just to name a few).  Symptoms can be hard to detect and can occur from 1 hour to 3 days after consuming an offending food. Most common offending foods include wheat/gluten, dairy, eggs, soy, tomatoes (nightshades), corn, peanuts, and shellfish.  A good book to read on this subject is called Your Hidden Food Allergies are Making you Fat by Roger Deutsch and Rudy Rivera, M.D.

Food Intolerances - A food intolerance involves the digestive system and occurs when a person has difficulty digesting a particular food, while food allergies and sensitivities involve the immune system.  A food intolerance can cause intestinal gas, abdominal pain or diarrhea. The most common are lactose intolerance--when a person lacks enough enzymes to digest lactose (milk sugar). People with a lactose intolerance experience symptoms of gas, bloating, and/or diarrhea after drinking milk or consuming foods that contain dairy products. Quite simply, when food can't be fully digested, it sits in the gut where microorganisms feed on the undigested food and produce bloating intestinal pain, and flatulence. Additionally, because the undigested food has a high osmolality, the body attempts to dilute it by drawing water into the digestive tract, subsequently resulting in loose stool or diarrhea.