What is a food allergy?
True food allergies involve an immune response to ingested food. Normally, our immune system functions to protect us from disease, by producing antibodies against foreign, harmful microorganisms and other microscopic particles. In a true food allergy, the body’s immune system mistakenly identifies a component in food as harmful and produces antibodies against it. The antibodies, in the form of IgE, recognize the “harmful” particle when repeatedly ingested, and trigger an immune response. Specialized cells, called Mast Cells, release histamine and other chemicals, resulting in the allergic reaction.
Symptoms include:
- Sneezing
- Congestion
- Hives
- Shortness of breath
- Hypotension (dangerously low blood pressure)
- Cardiovascular collapse
- Death
True food allergies include peanuts, tree nuts, shellfish, soy, shellfish and wheat. Individuals who are allergic to these substances will suffer from the symptoms listed above, even when ingesting very small amounts of the allergen. Additionally, allergic reactions generally get more severe with each exposure to the offending substance.
What is food intolerance?
In contrast, a food intolerance is a digestive system response to an ingested substance, rather than an immune response. Generally, the severity of the symptoms in a food intolerance is proportional to the amount of the irritant food ingested. For example, individuals who suffer from dairy intolerance (i.e. lactose intolerance) will suffer more severe symptoms when ingesting larger amounts of dairy. If they eat only a tiny amount, they may not suffer any symptoms. This differs from a food allergy: in food allergies, even a small amount of the allergen can lead to a full blown anaphylactic reaction.
Symptoms of food intolerance include:
- Nausea
- Stomach cramps
- Heartburn or gastroesophageal reflux
- Diarrhea
- Headaches
- Vomiting
What are some examples of Food Intolerance?
The four major categories of food intolerance include dairy intolerance, yeast intolerance, gluten intolerance, and fructose intolerance. Lactose (dairy) intolerance is the most common form of food intolerance, with estimates of affected adults ranging up to 75%, according to www.foodintol.com. Yeast and fructose sensitivity may affect of to 35% of adults, while gluten sensitivity is least common, at around 15% prevalence.
How are food allergy and food tolerance diagnosed?
The first step in diagnosis of food allergy is to identify symptoms. The symptoms of food allergies are common to all types of allergies. After suffering an allergic reaction, testing under physician supervision is needed to identify the offending agent. Two types of tests are utilized by allergy specialists: skin testing, and blood testing. The skin test involves injection of a small amount of the suspected agent, in a sterile form, injected in between the skin layers. A positive test results in swelling at the injection site within one hour. The blood test is used to detect IgE levels to specific allergens. Food intolerance, on the other hand, is best diagnosed using an elimination diet. The four potential offending food substances are listed above. After eliminating these foods, each is slowly reintroduced into the diet, one at a time, and the individual is monitored for a return of symptoms. This can help isolate the offending foods, which should then be permanently eliminated from the diet.
References:
http://www.webmd.com/allergies/guide/foods-allergy-intolerance
