An estimated four percent of people have a food allergy of some sort. Almost any food or ingredient can cause an allergic reaction in someone who is sensitive to it, but the most common culprits—collectively responsible for as many as 90 percent of severe allergic reactions to food—are the so-called Big Eight: cow’s milk, eggs, peanuts, tree nut such as almonds and pecans, fish, shellfish, soy, and wheat. Unfortunately, these are quite common ingredients in commercially available foods—indeed, without specifically looking, it’s difficult to fill a cart with only products that use none of these—and some, such as eggs and shellfish, have medical applications as well.
There has seemed, in recent years, to be a rise in food allergies. There are several factors at play in this. As more and more manufacturers and restaurants are accommodating allergies, people with allergies are becoming more visible, no longer confined to foods thy carefully prepare themselves in their own kitchen. In addition, milder allergies are recognized and addressed than in previous generations; people who once may have had to just live with it are having an easier time avoiding foods that don’t agree with them. Moreover, it is believed that children are exposed to fewer pathogens than in years past, leading a bored immune system to latch on to innocuous foodstuffs.
One thing that’s important for people living with allergies is to look carefully at food labels. Even trace amounts of an allergen, such as residue on a piece of equipment, can cause a reaction, which is why packaged food sold in the United States is required to note on the product label when an item contains or may have come into contact with any of the Big Eight ingredients. Lactose intolerance and celiac disease are not, medically speaking, allergies, but people with thee conditions need to avoid cow’s milk and wheat respectively. While recent studies have cast doubt on the severity of gluten sensitivity other than celiac, celiac itself and wheat allergy are very real.
One of the most common tests to diagnose allergies is the skin prick test, in which food proteins are injected into the skin at a specific place. If the skin shows a reaction, this may indicate an allergy. While this test has extremely low instance of undersensitivity, it is often oversensitive. Trial elimination may be done as a followup or it may be the first test used. As the name suggests, suspected allergens are avoided for two weeks; if symptoms disappear, an allergy has been found.