In the middle of the night in Atlanta, I got a frantic call from my daughter in Chicago. “Daddy, I’m so sorry to wake you, but Michael just ate a little piece of cashew and now his face is swollen and he’s breaking out in a rash all over his body.” Once I realized that her voice wasn’t just part of some bad dream, I gave my doctor’s orders: “Give him Benadryl and take him to the emergency room immediately!”
As a board-certified allergist for 25 years, I recognized that my grandson was having a potentially serious allergic reaction and that his symptoms could get worse-much worse. Fortunately, by the time they arrived at the hospital, the swelling had subsided and his hives had resolved.
Even though my grandson’s diagnosis was easy to make, food allergies can be one of the most frustrating and complex allergy issues facing physicians, patients, and families. If you consider the unlimited number of foods and additives we consume today, the variable time between ingestion and allergic reaction, and the varied and often-subtle symptoms, it seems miraculous when an allergy-triggering food is actually identified.
Food Allergies In Children: A Disturbing Trend
Ask anyone who raised children 25 years ago if they ever heard of food allergies back then, and the likely answer will be no. Yet today, who doesn’t know a child-if not several kids-who have severe food allergies? Pediatricians and allergists are observing first-hand that food allergies in infants and children have increased to epidemic proportions over the last few decades. Studies have shown that in the under-18 age group, the prevalence of reported food allergies increased 18% between 1997 and 2007. Approximately 4% of Americans are estimated to have food allergies. That’s more than 12 million individuals. The prevalence of food allergies is even higher-6% to 8%-in infants and young children under three years old.
Any type of food can trigger an outbreak, yet the “Big 8″ account for more than 90% of all cases: milk, eggs, peanuts, tree nuts, fish, shellfish, soy, and wheat. Sesame is quickly becoming another common cause of allergies, especially in those with Mediterranean diets. The good news is that the incidence of documented food allergies decreases with age, probably due to the development of tolerance in children allergic to milk, wheat, soy, and eggs. Of the 2.5% of children allergic to milk, approximately 80% will “outgrow” their allergy by age five. Kids with peanut or tree nut allergies aren’t as lucky: Recent studies have shown that only about 10% to 20% of children will lose their allergy as they age.
Pediatric Food Allergies: Instantaneous Outbreak Of the two main types of allergies, the “immediate hypersensitivity reaction” gets the most hype, probably because you can see the symptoms (whether it’s hives or swelling) right away. The other kind is aptly named “delayed hypersensitivity reaction.” Otherwise known as IgE-mediated, the immediate allergic reaction is the best understood and the most easily diagnosed. Yet it can also be the most serious. When the proteins in an allergenic food come in contact with an IgE antibody (located in the skin, gut, and airways, or in the blood), a cascade of cellular events occurs resulting in the release of histamine and a multitude of other chemical mediators. The rapid release of the histamine and other chemicals is what causes the allergic reaction. The outbreak, which generally occurs within minutes of ingestion, can be relatively mild or severe. Moderate symptoms might include a rash, generalized itching and redness of the skin, facial or eyelid swelling, abdominal cramping, vomiting and/or diarrhea. These can be treated with a quick-acting antihistamine and tend to run their course over a few minutes to hours. The most severe reaction is called anaphylaxis, which can occur instantaneously or a few minutes after ingestion. As a general rule, the quicker the onset of symptoms, the more serious the reaction is likely to be. Symptoms of anaphylaxis might include those mentioned above, but can also rapidly progress to breathing difficulties and chest tightness (due to bronchial constriction and swelling of the airways), a drop in blood pressure leading to shock-and even death. Epinephrine (also known as adrenalin), which is available for self-injection in the form of an Epipen and other auto-injectors, must be given immediately and repeated if necessary. Foods that commonly cause severe reactions include peanuts, tree nuts, fish, sesame seeds, milk, and eggs. The most serious reaction I ever witnessed resulted from the ingestion of a single pine nut. That tiny seed (it’s not really a nut) transformed a healthy teenager into a critically ill patient within a matter of minutes. Fortunately, the patient recovered, but anaphylaxis can be fatal if not treated immediately and aggressively. If your child has ever had an immediate allergic reaction to a food, you should consult with a board-certified allergist. To identify or confirm the symptom-triggering food, the allergist will likely give a few tests, either through the skin or blood. From there, you and your allergist can come up with a plan to eliminate the food from your child’s diet and discuss prevention and management of future reactions.
Delayed Allergic Reactions: Subtle Yet Elusive
While less dangerous in terms of one’s immediate health, the “delayed allergic reaction” can be much more difficult to diagnose and treat. As the name implies, it can take hours or even days after ingestion for the symptoms to show up, making it harder to establish a cause-and- effect relationship. The typical symptoms can involve several organ systems and may be quite subtle in their presentation. In addition to the classic allergy symptoms (think nasal congestion, a runny nose, and a rash), delayed reactions may also present with very vague and nonspecific symptoms, such as frequent headaches, recurrent or chronic abdominal pain, fatigue and lethargy, irritability, dark circles under the eyes, leg pains, and recurrent ear or sinus infections.
Part of the difficulty in diagnosing these food reactions is that there’s no reliable allergy test that can accurately identify or predict a delayed outbreak. Skin testing and blood tests aren’t helpful because they only measure the IgE antibody, which is responsible for immediate reactions. Research has not yet identified the antibody or antibodies responsible for delayed reactions, although there has been considerable interest and research in the possible role of the IgG antibody. Blood tests to measure this antibody are available, but its reliability as a predictor of delayed allergy has not yet been established.
So how can you figure out if your child’s symptoms are the result of something he or she is eating? The best method we have right now is to eliminate the suspected food (or drink) from your kid’s diet for four weeks. If you notice a significant improvement in symptoms, you’re ready for the challenge phase: Serve the food in question for several days straight. If the symptoms start recurring, you can be relatively sure that a cause-and-effect relationship has been established. Even after avoiding the food culprit, it can still take a few weeks for symptoms to completely disappear, so be patient.
By far, milk and other dairy products are the most common cause of this type of reaction. Over the years, many teenagers have walked into my office with their parents complaining about stomach discomfort and profound tiredness. By the time they’ve come to see me, they’ve usually been through various tests and have seen multiple physicians, including gastroenterologists, and have often been diagnosed with irritable bowel syndrome. After hearing about their saga and symptoms-and seeing the dark circles under their eyes and their pale, sallow complexion-I can usually tell that it’s a dairy allergy. Fortunately, many responded dramatically to a few weeks off of milk. They couldn’t believe that the innocent act of drinking milk and eating dairy products could make them feel so ill-and that avoiding these products could restore their good health and vitality in such a short time.