A food allergy happens when your immune system reacts to something that you’ve eaten.
When you eat something you are allergic to, your body makes antibodies. Over time, sometimes as soon as the second time you eat it, the antibodies spring into action, starting a process that includes the release of lots of histamine to fight what it believes is invading your body.
Allergies affect more than 50 million people in the United States -- the poor souls who sniffle, sneeze, and get all clogged up when face to face with the allergen (or allergens) that set them off.
For many, allergies are seasonal and mild, requiring nothing more than getting extra tissue or taking a decongestant occasionally. For others, the allergy is to a known food, and as long as they avoid the food, no problem.
But for legions of others adults, allergies are so severe it interferes with...
Tree nuts (such as walnuts, pecans, almonds, pine nuts, and Brazil nuts)
How Are Food Allergies Diagnosed?
If you keep a food diary, your doctor will have a better starting point to figure out foods that could trigger your allergies.
Your doctor may suggest a food elimination diet. If he does, you may be asked to eliminate one or several foods to see if the reaction goes away.
Oral food challenges -- exposing the person to the suspected food under medical supervision -- are thought to be helpful as well. These are usually done after the elimination diet.
Your doctor may do a radioallergosorbent blood test (he may call it a RAST) to see how many antibodies your immune system makes. High levels of some antibodies can help your doctor spot specific food allergies.
Some food allergies are very mild, and in difficult-to-diagnose cases, a promising new antibody test may help. More research is needed. Also, there are now genetic tests, especially for gluten and celiac (wheat, barley, rye, and some oats).