Food Allergy Testing & Treatment Questions and Answers
Dr. Jon E. Stahlman, MD specializes in the diagnoses and treatment of adult and pediatric food allergies. Come to The Allergy & Asthma Center today! We are ready to serve you. For more information, please call us or book an appointment online. We serve patients from Lawrenceville GA, Atlanta GA, Conyers GA, Suwanee GA, Duluth GA, Grayson GA, Decatur GA, Brookhaven GA, Lithonia GA and Covington GA.
Food allergies can be one of the most frustrating and complex allergy issues facing patients, families and physicians. The large variety of foods children and adults consume on a daily basis and the variable timing of reactions present unique challenges in making the diagnosis of food allergic reactions. Although an individual may be allergic to almost any food, there are eight foods that account for 90 percent of all food allergy reactions. These are: milk, eggs, peanuts, tree nuts, fish, shellfish, soy, and wheat.
How prevalent are food allergies?
According to the Food Allergy Research Education organization over 32 million Americans have food allergies including 1 in 13 children. The prevalence of food allergies is highest (6-8 percent) in infants and young children under three years old. Fortunately, the incidence of documented food allergies decreases with age, probably due to the development of tolerance in children allergic to milk, eggs, wheat and soy. For children allergic to milk and eggs a majority will “outgrow” their allergy by five years of age. Of all of the foods, peanuts, tree nuts and seafood allergies are least likely to be outgrown. Studies have shown that only about 20 percent of children will lose their hypersensitivity to peanuts.
Are there different types of food allergies?
For purposes of simplicity, food allergies can be divided into two types: the immediate hypersensitivity reaction and delayed hypersensitivity reaction.
Immediate hypersensitivity food reactions
The immediate allergic reaction is the best understood, most easily diagnosed, but the most serious of all allergic reactions. This reaction represents the “classic” allergic reaction. At the cellular level, an allergen (the food protein) comes in contact with IgE antibodies specific to that food in the blood, resulting in the release of histamine and a multitude of other chemical mediators. Once released into the tissues and circulation, these mediators cause an immediate allergic reaction. This reaction, which generally occurs within minutes after ingestion of the allergenic food, can cause a spectrum of symptoms from relatively mild to severe. Symptoms of a relatively mild to moderate reaction might include a rash (urticaria, commonly referred to as hives), itching, generalized redness of the skin, heat, facial or tissue swelling. Such reactions are often treated with a quick acting antihistamine and generally run their course over a few minutes to hours.
The most severe allergic reactions (known as anaphylactic reactions), generally have a rather quick onset after the food is eaten. Symptoms might include those mentioned above, but can rapidly progress to difficulty breathing (chest tightness due to bronchial constriction and swelling of the airways), abdominal pain, profuse vomiting and diarrhea and or a drop in blood pressure leading to shock, and even death. Anaphylaxis, or impending anaphylaxis, must be treated immediately. Epinephrine (adrenaline) is the drug of choice for treatment. It is available for self administration (Epinephrine Auto Injection USP, Epipen, Auvi-Q, Impax Epinephrine generic for Adrenaclick or Symjepi) and should be given immediately. It can be repeated if necessary.
Any person who has possibly experienced an immediate allergic reaction to a food should consult a board certified allergist. The allergist will likely test the patient, either through the skin or blood, in order to identify or confirm the allergenic food. Once it has been determined which food(s) caused the immediate allergic reaction, the allergist will consult with the patient and family about the elimination of the food(s) from the diet and the management of any further reactions.
Delayed hypersensitivity food reactions
A delayed food allergy reaction, while usually less dangerous in terms of one’s immediate health, can be much more difficult to diagnose and treat. As the name implies, there is often a delay of usually many hours between the time of ingestion and the onset of symptoms, making the history less valuable in establishing a cause and effect relationship. Allergy skin testing and RAST or ImmunoCap blood tests are not usually helpful in making a diagnosis, as they measure only the IgE antibody, the antibody responsible for immediate reactions. The exception to these reactions might be an allergy to meat in patients with a history of Lone Star tick bites or allergic reactions to the anti-cancer drug Rituxan (cetuximab). In those patients blood testing for an allergy to alpha gal (a sugar molecule only found in mammalian meat) might be helpful.
The optimal method of determining whether one is suffering from a delayed hypersensitivity reaction, and to which food(s), is the elimination diet. Elimination or reduction of symptoms after the avoidance of the offending food(s) from the diet may take weeks to assess.
Can infants be allergic to foods?
Food allergies in infants are especially challenging. Symptoms of a food allergy may include colic (irritability), excessive spitting (even projectile vomiting), rashes including eczema or hives, nasal symptoms including congestion and/or runny nose, coughing or wheezing, diarrhea (sometimes with blood), and even poor weight gain.
The most common food allergy in children under a year is cow’s milk. It is important to know that 20-30 percent of milk allergic babies are also allergic to soy as well.
It is also possible for babies who are exclusively breast fed to be allergic to a food protein being passed through the nursing mother’s milk.
Can one be allergic to more than one food in a food family?
It is also important to be aware that many foods can cross react with other foods within the same food group or family. Familiarity of food groups is important for the food allergic individual.
What is the best treatment for food allergies?
The treatment advocated by allergy specialists for food allergies for many years has been avoidance. Avoidance works well for most food allergies but does present challenges for patients and their families. Recent research has suggested that there may be other forms of therapy depending on the age of the individual. Studies have shown the prevention of certain food allergies is now possible with early introduction of that food. Currently the American Academy of Pediatrics recommends introducing peanut protein (in an infant safe form) starting at age 6 months if possible for most children (and as early as 4 months for high risk children with eczema or an egg allergy).
New therapies to protect patients who have been diagnosed with a food allergy are also nearing everyday use including forms of oral immunotherapy and possibly patches that can be worn to prevent allergic reactions. Your board certified allergist is the best resource for helping decide if any of these therapies are best for you or your child.