While approximately 40 to 50 million Americans have allergies, only 1.5% to 2% of all adults are allergic to foods. Adverse reactions to foods are common among young children, affecting 6% to 8% of infants in the first 3 years of life. The following information addresses commonly asked questions regarding food allergy.
Allergic reactions to foods usually appear within minutes to a few hours after eating the offending food. The severity of the symptoms varies from one person to another. Mild symptoms may include a runny nose with sneezing, while a highly allergic person may experience severe and life-threatening symptoms such as swelling of the tongue, lips, and throat, and difficulty breathing.
The most common symptoms of food allergy involve the skin and gut. Skin rashes include hives and eczema. Symptoms involving the gut include vomiting, nausea, stomach cramps, indigestion, GERD and diarrhea. Food allergies have been shown to play a significant role in the cause of eosinophilic esophagitis (EoE). Other symptoms of food allergies include cough, wheezing, and rhinitis (itchy, stuffy, runny nose, and sneezing). Anaphylaxis, a severe allergic reaction that involves many organ systems, may occur.
Food allergies in infants can present with one or more of the above symptoms as well as colic, irritability, poor sleeping patterns and refusal to breastfeed or fussy nursing behavior.
Peanuts, cow’s milk, soy, wheat, eggs, fish and shellfish are the most common foods causing allergic reactions. However, almost any food has the potential to trigger an allergic reaction. Foods most likely to cause anaphylaxis are peanuts, tree nuts, and shellfish.
If an individual is allergic to a particular food, they might be allergic to related foods. For example, if an individual has an allergy to almonds, testing may show that this individual is not only allergic to almonds but also to one or two other members of the tree nut family such as cashews and walnuts. Our allergists can help identify the offending food allergen and the cross-reactive foods.
Although food allergy occurs most often in children, it can appear at any age and can be caused by foods that had been previously eaten without any problems.
Finally, cultural difference in food ingestion affects the likelihood that a certain food will cause allergy. For example, there is a high prevalence of fish allergy among Scandinavians, of rice allergy among the Japanese, and of sesame allergy among the Israelis.
Eczema (atopic dermatitis) is one of the most common skin problems today. Eczema is a skin condition characterized by chronic itching that leads to red, swollen, scaly patches. This condition usually appears during the first year of life and generally involves the face, torso and creases of the extremities. About one-third of infants and young children with eczema have food allergy. Appropriate diagnosis of food allergy and elimination of the offending allergen leads to significant clearing or improvement of the skin rash in many young children with both eczema and food allergy. Food allergens may be triggers for some acute eczema exacerbations.
Having a family history of allergies seems to be the main reason why certain people develop allergies, while others don’t. If both parents have allergies there is approximately a 75% chance of being allergic. If only one parent has allergies, there is a 30% – 40% chance of developing some form of allergy. If neither parent has allergies, there is still a 15% chance of developing allergies.
Some people know precisely which foods caused their allergic symptoms; however, other individuals need the expertise of an allergist to determine the offending food, especially when the food is not obvious, or the symptoms (for example, eczema) appear many hours after ingesting the food. Our physicians will begin by taking a thorough medical history. Skin testing may be performed, in which a diluted amount of food extract is placed on the skin, followed by a light puncture or scratch. This procedure is safe and is usually not painful. Within 15 minutes, a positive reaction (similar to a mosquito bite) will appear.
Once the diagnosis of food allergy is made, the most effective treatment is to eliminate the food from the diet completely. Therefore, ingredient labels of food products must always be checked and scanned for other “hidden” names.
Our allergists will help the family of a food allergic infant or child with adjusting their diet ensuring nutritional needs are met as well as becoming proficient label readers.
Children with food allergies should have a clearly defined plan of action for handling situations in which they accidentally ingest a food allergen. An injectable epinephrine device should be carried by individuals with food allergies.
Strict adherence to an elimination diet appears to promote the process of outgrowing a food allergy. The majority of children with allergies to eggs, cow’s milk, and soy will eventually outgrow their allergy although it may take a longer time than originally thought. Unfortunately, allergies to peanuts, tree nuts, fish, and shellfish are generally considered life-long allergies. In rare cases, these allergies are outgrown but careful testing and an oral food challenge conducted in the office is required.
Patients who are cautious and comply with their allergist’s recommendations can bring food allergy under control.
A recent study, Learning Early About Peanut Allergy (LEAP), published in the New England Journal of Medicine showed that early oral introduction of peanuts could prevent peanut allergy in high-risk infants who are not yet allergic to peanuts. This is a change from the former recommendation of avoiding peanuts as a strategy to prevent peanut allergy.
High-risk infants include:
The LEAP study findings suggest that early and sustained consumption of peanut products was associated with a substantial and significant decrease in the development of peanut allergy in high-risk infants. Conversely, peanut avoidance was associated with a greater frequency of clinical peanut allergy than was peanut consumption.
Based on this study, high-risk infants should be evaluated prior to having peanuts introduced into their diets. Our allergists will take a history, perform peanut testing by skin test and assess peanut IgE blood levels. Our physicians will then determine whether peanuts can be safely introduced into the infant’s diet via a controlled in-office oral peanut challenge.