Food Allergies 101
Health and Wellness
July 31, 2007
Food Allergies 101
HEALTH & WELLNESS
Food allergies are on the rise, says an expert panel made up of members from the National Institute of Allergy and Infectious Diseases (NIAID) and the National Institutes of Health (NIH). The panel found that, based on its increasing prevalence, food allergies have emerged as a significant public health problem. Currently, food allergies affect some 12 million Americans.
A food allergy is a reaction to a food that triggers an immune system response because the body perceives the food to be harmful. The most common reaction occurs when the body creates immunoglobulin E (IgE) antibodies to the food. This is the same antibody that results in a classic reaction (i.e. itchy eyes and nose) to cat dander exposure. But since food is taken internally, and not just contacted through the nose and eyes, systematic allergic symptoms can result, ranging from mild to severe.
Food allergic reactions that do not involve IgE antibodies at all are primarily gastrointestinal immune responses to foods, many of which occur in infants and are later outgrown. A common non-IgE-mediated food allergy that is not outgrown is Celiac Disease, which affects up to one percent of the population. For these individuals, exposure to gluten proteins in wheat, rye and barley triggers an inflammatory response.
When someone actually has a reaction, it usually starts within a few minutes of eating the food in 75% of patients. Symptoms usually begin in the mouth with a tingling sensation, a metallic taste, burning or itching. Some people have more severe first symptoms like hives, swelling of the lips, nausea, abdominal cramping, wheezing or shock.
Interestingly, some 30% of people who believe they have allergies may actually have what is known as food intolerance, says the NIH – a reaction to a food not mediated by the immune system. These types of reactions can be due to deficiency of enzymes that the body needs to break down a substance, as in the case of lactase, which metabolizes the milk sugar, lactose. In fact, the majority of the world’s population is actually lactase deficient after early childhood, so lactose intolerance is quite common worldwide.
Allergic disorders in general appear to have to been on the rise over the last two decades, along with an increase in autoimmune disorders. Dr. Suzanne Teuber, Professor of Medicine at UC Davis and Training Program Director of the UC Davis Allergy and Immunology Fellowship Program, says that there are several theories as to why this is happening.
“The main theory is that our immune systems are not getting the correct stimuli to invoke proper functioning of immune regulatory cells during early life. Avoidance of infections, antibiotic use, and cleanliness are also being studied,” she says. “We do know that kids who grow up down and dirty on farms are less likely to have allergies.”
About six to eight percent of children under the age of four have a known food allergy, but many of them will outgrow it. About 20% of children will outgrow peanut allergy. Allergy to cow’s milk, eggs, wheat and soy is usually outgrown by age three. If a child still has a food allergy by school age, however, they are less likely to outgrow it. Most food allergies develop early in life; allergies to seafood and fruits and vegetables may not appear until teen or adult age.
“When adults have allergies that seem to appear suddenly or later in life,” says Teuber. “we often hear that the last time they ate a shrimp cocktail, for example, they had itching in the throat, and didn’t think much of it until they ended up in the emergency room with difficulty breathing the next time they ate shrimp.”
Currently, the only way to manage food allergies is to avoid reaction-producing foods and treat symptoms – even with many promising NIH studies in the works. That means food labeling will continue to be important. New food allergen labeling laws require products containing the “Big 8” foods – cow’s milk, egg, peanut, soy, wheat, tree nuts, fish and crustaceans – to be identified. Beware though: Other food allergies are not covered.
“A ‘natural flavoring’ that is included in trace amount in a food does not need to list the components in the flavoring except for the Big 8 allergens, even when something like mustard seed may be one of the components,” says Teuber.
Most severe food allergic reactions occur outside the home, where people may not have the opportunity to carefully read the label of each ingredient that went into a dish at a restaurant. Cross-contamination also remains a big concern, especially with prepared foods. To prevent cross-contamination, Teuber recommends good manufacturing processes and full-disclosure of labeling, even of ingredients in small quantities.
“No secret ingredients, please!” she adds.