An estimated 11 million Americans, suffer from food allergies, which accounts for roughly 20.000 emergency room visits annually. Each year, as many as 150 to 200 people die from food-allergic reactions, involving severe swelling in the throat and cardiovascular collapse.

Food intolerance, poisoning or allergies are not synonymous.  An undesirable reaction to a food such as lactose that does not involve the immune system is the most common food intolerance.  In such cases, an enzyme that is needed to digest milk sugar (lactose) is not present and therefore, after ingestion of dairy products, symptoms such as gas, bloating, and abdominal pain typically occur.  

Food borne illness, or "food poisoning," occurs when food contaminated with bacteria or other pathogens, such as parasites or viruses, is consumed. Typical symptoms of food poisoning include vomiting or diarrhea, which usually occur several hours later.

Genetic predisposition can allow individuals to produce allergy antibodies called immunoglobulin E to a certain foods.  When these IgE antibodies react with certain foods, histamine and other chemicals are released causing an allergic reactions in different parts of the body:  gastrointestinal tract( abdominal pain, diarrhea, nausea, vomiting), respiratory system ( swelling of the throat or mouth, wheezing, difficulty breathing, coughing), cardiovascular system ( drop in blood pressure, feeling of impending doom, loss of consciousness, skin and create symptoms include hives, eczema, asthma, abdominal pain, nausea, vomiting, diarrhea and even anaphylaxis.  Even though any type of food can be an allergic trigger, tree nuts, eggs, soy, milk, wheat, fish, shellfish account for 90% of all food-allergy reactions.

Urticaria (hives) is an outbreak of red bumps or patches called wheals that appear on the skin caused be the release of histamine and other chemicals.   Foods suspected of causing acute urticaria are often identified by when they were eaten prior to the development of urticaria.

The most dangerous allergic reaction is known as a generalized allergic reaction (anaphylaxis) that can produce shortness of breath, wheezing, airway swelling, increased heart rate, loss of consciousness, and even death. 

Anaphylaxis usually requires immediate medical treatment with epinephrine, antihistamine and even corticosteroids.  Most often, anaphylaxis is associated with the ingestion of peanuts, nuts, fish and shellfish, peanuts being the leading cause, followed by shellfish, fish, tree nuts and eggs.  It has been recommended that peanut-allergic patients avoid tree nuts (pecans, walnuts, almonds, etc), and vice versa, as an extra precaution.