Food allergies – How do you know if you have them?
Posted in Allergies on May 14, 2010
An article in the New York Times published yesterday casts doubt on the widespread reported incidence of food allergies in the general population. The article states that the true incidence of food allergies is 5% in adults and 8% in children versus the approximately 30% of people in the general population who self-report food allergies. Why is there such a large discrepancy? The main problem comes from the fact that most people do not truly understand what an allergy is. An allergy is the body’s response to a foreign substance that involves the immune system. Many people can have reactions or side effects to substances, such as food, environmental irritants, and medications, that are not related to an immune response. One example given in the article is headaches caused by chemicals in wine called sulfites. This intolerance is not due to the body’s immune response and is therefore not an allergic response. Another example is the nausea and upset stomach that many people have after taking certain antibiotics or narcotic pain medications. These symptoms are side effects of the medication that are completely unrelated to the body’s immune response are therefore not true allergies. Signs and symptoms that are associated with a true allergic response include itching, development of a rash, flushing, shortness of breath, and increased heart rate. Other signs and symptoms commonly associated with environmental and food allergies include watery eyes, sneezing, and nasal congestion.
The most common way to test for allergies is either by a skin testing, where concentrated extracts of substances are injected into the skin to elicit a response, or by testing the blood for specific allergy-related antibodies known as IgE to different substances. As emphasized in the article, testing alone cannot always determine whether an allergy is present – a thorough history must also be incorporated to determine whether a specific foreign substance is causing a significant allergic response or not.