The immune system helps fight off infection by targeting infectious agents. Sometimes it targets substances that do not cause infections and attempts to defend your body against those substances. This results in an allergic reaction.
Therefore, allergies occur due to a heightened sensitivity of the immune system to common substances. When those substances cause an allergic reaction they become known as allergens.
A food allergy is a reaction to the protein in certain foods. Symptoms of food allergy include gastrointestinal distress as well as swelling of the mouth, lips, and other mucosal tissue that the food comes in contact with.
Common foods that people are allergic to include nuts, milk, eggs, wheat, soy, and shellfish.
Skin allergies occur when an allergen comes in contact with the skin. A rash with redness, swelling and, itching may develop. The most common skin allergens are poison ivy/oak, insect bites, household chemicals and detergents, and metals like nickel and gold.
Learn more about skin allergy.
Respiratory allergies occur when minute particles suspended within the air are breathed in. These particles affect the tissue of the nose and respiratory passages causing them to tighten and release mucous. As a result you feel stuffed up and are prone to coughing and sneezing.
Pollen, dust, and animal dander are the most common causes of this allergy.
Learn more about respiratory allergy.
How can you know what's causing your allergies? What are some possible causes that you wouldn't normally suspect?
It might have been a rash, or a stomach problem, or even a respiratory ailment, but whatever it was, they couldn't figure out what caused it. Well, it might have been something you ate. Without knowing it, you might suffer from a hidden food reaction. Nearly one percent of adults and seven percent of children under five have at least one food allergy-an abnormal immune system response triggered by exposure to "foreign" proteins. Sometimes the reaction can be severe, other times not.
Most common foods that cause allergies:
There is another condition that produces similar reactions to allergies, but does not involve the immune system. This is known as food intolerance and affects anywhere from 5% to 50% of adults. The lack of one or more digestive enzymes is what causes many cases of food intolerance, which impairs the bodies ability to break down certain proteins.
Most common foods that cause intolerance:
Obviously, all food allergies and intolerance don't affect everyone the same. A rash might appear on one person while a stomach ailment might plague another all from the same food item. This is why it is often difficult to diagnose these conditions, and indeed, why many misdiagnoses are made. If you feel that this might be your problem, there is a surefire method that an allergy specialist can use to isolate your reactions to foods.
It is known as the "elimination and challenge diet." It consists of a four-week "elimination" phase where all suspect foods are omitted from your diet. During this cycle, symptoms generally disappear. The "challenge" phase follows and can last up to a few months. During this time, suspect foods are tried one at a time to determine which cause the reactions. It's painless (unless one of the suspect foods is your absolute favorite) and it works. Then, just like the old saying "if it hurts, don't do it," if you get a reaction from it, don't eat it.