Sometimes, we have negative experiences with food and declare them "allergic reactions" when really these are instances of food intolerance. A food intolerance is also an abnormal reaction to food, but it can take many forms and never involves the release of IgE, which occurs only during allergic reactions.
Food allergies aren't the same as food intolerances. For instance, lactose intolerance isn't an allergy. Having a toxic reaction -- as you may if you eat tainted shellfish -- isn't an allergic reaction either, and neither is food poisoning.
Food intolerance occurs far more often than food allergy, but shares many of the same symptoms as (such as nausea or stomach pain). The key difference is that food intolerance is a response of the digestive system, while food allergy derives from the function of the immune system.
A negative reaction to milk could either be lactose intolerance or milk allergy. In some cases, milk allergy, which is one of the most common food allergies in children, can resolve itself entirely as children age. Lactose intolerance, which is more commonly developed in adulthood, is a lifelong condition. While other allergies -- such as wheat allergy -- may also diminish with time, some can affect you throughout your entire life.
An increased alarm and awareness of food allergies likely brings with it an increased likelihood of mistakenly declaring a negative reaction to food to be an allergy.
You probably don't know too many people who are allergic to apples or carrots (depending on what type of crowd you run with), but more adults are allergic to fruits and veggies than they are to peanuts. Most of us tend to think of peanuts as the most common allergy because of the frequency with which we hear about it in the media. Peanuts earned their star status for their potential to cause deadly allergic reactions, not for the frequency of which that actually happens.
That's not to say it never happens, however: While "only" 0.6 percent of the U.S. population is allergic to peanuts, that still represents more than 1.8 million people of all ages who are at some degree of known risk of experiencing a more dangerous reaction than occurs with other types of food allergies [source: Stoppler].
Next: Seriously, should we panic about food allergies?