By Carina Venter, PhD, RD and David Fleischer, MD
Year after year, despite dramatic gains in research, some misconceptions are remarkably stubborn, both among patients and their doctors. We canvassed our friends in practice and research around the world to compile a list, and there was broad consensus that these are the most prevalent. (See list below of those who helped.)
1. You can’t be allergic to a food that you have not eaten
False:
Sensitization to foods can happen via the skin, particularly in children with eczema(1) During pregnancy, the fetus can be exposed to allergens their mother is eating; during breastfeeding, allergens can be passed to the infant via breast milk(2).
However, allergen avoidance during infancy when children suffer from eczema, or during pregnancy or lactation, does not seem to prevent food allergies. Allergen avoidance during pregnancy and breastfeeding is not advised until we understand the role of dietary intake better. Eating of allergens early in an infant’s life, however, seems to protect against the development of food allergies.
2. You can’t be allergic to rice, and most definitely not to banana or sweet potato!
False: Imagine the difficulties of trying to convince food allergy sceptics that your child is really peanut-allergic. Now try to imagine telling them that your child is allergic to rice! Parents who make this claim are generally met with amused condescension–“No one is allergic to rice!” Unfortunately, many of the allergens involved in food protein-induced enterocolitis syndrome (FPIES) are “atypical” allergens such as rice, sweet potato, and banana(3). (But try to explain FPIES to the average skeptic.) So yes – severe allergic reactions to foods not considered to be part of the top eight allergens are possible.
3. The size of your skin prick test (SPT) or the level of food-specific IgE tests predicts the severity of reactions
False: The size of a SPT or the level of specific IgE to a food indicates the likelihood of being allergic but not the severity of the reaction, i.e., the larger the size of the SPT or the higher the level of serum specific IgE the more likely you may be allergic to that food(4). The reaction history remains the most important indicator.
4. Each allergic reaction to a food becomes subsequently worse
False: There is no evidence to indicate that each allergic reaction becomes worse. Many people who had only mild symptoms in the past, end up with anaphylaxis on subsequent exposure(5). There is however some evidence that a history of anaphylaxis and suffering from eczema or asthma, may increase the risk of anaphylaxis(6).
5. Everyone with food allergy develops anaphylaxis
False: Many people with IgE-mediated food allergies never develop anaphylaxis. There are a number of factors that indicate if a person may develop anaphylaxis, including(5):
– Presentation of the food allergen (e.g. baked or not, fat content*)
– Infections
– Immunological and hormonal factors
– Behavior (e.g. risk taking, alcohol)
6. If you are allergic to one peanut or a tree nut, you need to avoid all nuts
False: Individualized avoidance of nuts should be advised to those with nut allergies – taking into account the family’s preferences/needs. About one-third of patients with peanut allergy may have tree nut allergies. People with certain tree nut allergies often tolerate other tree nuts. The tree nut allergies that most often co-exist are: cashew and pistachio; walnut and pecan, although you can be allergic to one of these but not another(7).
7. My child reacts to corn starch or corn syrup in foods (most often corn syrup in infant formula)
False: Although we can find no studies to reference, personal discussions with food scientists confirm that there are only trace amounts of protein left in corn starch and undetectable amounts in corn syrup, glucose syrup, dextrose (granular) or high fructose corn syrup. Many years of clinical practice, using these products in corn-allergic individuals, have reassured us that they are perfectly safe to use from an allergy point of view, although added sugar presents other problems.
8. I tolerate soy/peanut/sesame/tree nut oils
Perhaps true: The processing of oils across the world differs a lot, and even we find it confusing. Check to find out how the oil was produced: refined/expeller/heat-pressed oils, including the big brand names, are safer to eat, but crude/cold-pressed oils are best avoided due to a higher chance of having more residual protein.
9. My/his/her food allergy is not severe as I can eat(or /my child) can eat “trace amounts” of the foods
False: Many people belief that if they have safely eaten a product that states “may contain traces”/”produced in a factory” that they are tolerant of “trace amounts” of the allergen. This is, however, not true. “May contain” is a legalism, not a guarantee that any allergen is present. Most products with some kind of “may contain” warning do not have any detectable contamination, and those that do, contain a range of different amounts. It is also important to remember that some products without a “may contain” warning may contain trace amounts of the allergen(8).
10. Everyone with an allergy needs to avoid even trace amounts of the food
False: We change “strict” avoidance to “individualized” avoidance in every paper we review. We have long passed the times era when all food-allergic individuals have to strictly avoid allergen exposure. We understand that some people can tolerate baked milk and egg(9). Oral and epicutaneous immunotherapies have also made it possible to tolerate allergens, either fully or to some degree(10).
11. A baby/child that who is gaining weight cannot have a food allergy
False: Many infants with food allergies have a normal, perhaps even increased weight, and just referring to the weight to make a diagnosis will lead to a lot of misdiagnosis(11). Picky eating may be a sign that the child is uncomfortable eating certain foods, and parents compensate by relying on fattening foods.
12. Breastfed babies do not develop food allergies
False: Particularly in the case of cow’s milk allergies, where over 40% of babies with milk-induced proctocolitis, a non-IgE-mediated food allergy, are exclusively breastfed.(12)
13. If you do not have IgE-mediated food allergies, it is just an intolerance
False: Although the exact mechanisms of non-IgE/gut-related food allergies are not fully understood, it is clear that the immune system is involved in non-IgE-mediated food allergy; strictly speaking, intolerances are not immune-mediated(13), most prominently lactose intolerance, which results from an enzyme deficiency.
14. Young infants will have false negative SPTs
False: SPT can be performed from any age. SPT of very young infants may be smaller than older children, but there is no lower age limit to perform SPT or food-specific IgE tests(14).
15. IgG tests are reliable to test for food intolerances
False: Our present knowledge regarding IgG indicates that IgG4 is marker of food intake or development of tolerance (it is sometimes difficult to separate the two), but there is no association with IgG to a food and food intolerance to it(15).
* High fat content allows you “tolerate” the allergen to a much higher dose BUT then have very severe reactions once you react – i.e. you miss those initial warning symptoms. Hence using low-fat peanut flour for challenges.(16)
1. du Toit G, Tsakok T, Lack S, Lack G. Prevention of food allergy. J Allergy Clin Immunol. 2016;137(4):998-1010.
2. Pastor-Vargas C, Maroto AS, Diaz-Perales A, Villalba M, Esteban V, Ruiz-Ramos M, et al. Detection of major food allergens in amniotic fluid: initial allergenic encounter during pregnancy. Pediatr Allergy Immunol. 2016.
3. Venter C, Groetch M. Nutritional management of food protein-induced enterocolitis syndrome. Curr Opin Allergy Clin Immunol. 2014;14(3):255-62.
4. Peters RL, Allen KJ, Dharmage SC, Tang ML, Koplin JJ, Ponsonby AL, et al. Skin prick test responses and allergen-specific IgE levels as predictors of peanut, egg, and sesame allergy in infants. J Allergy Clin Immunol. 2013;132(4):874-80.
5. Turner PJ, Baumert JL, Beyer K, Boyle R, Chan CH, Clark A, et al. Can we identify patients at risk of life-threatening allergic reactions to food? Allergy. 2016.
6. Flinn A, Hourihane JO. Allergic reaction to peanuts: can we predict reaction severity in the wild? Curr Allergy Asthma Rep. 2013;13(6):645-50.
7. Brough HA, Turner PJ, Wright T, Fox AT, Taylor SL, Warner JO, et al. Dietary management of peanut and tree nut allergy: what exactly should patients avoid? Clin Exp Allergy. 2015;45(5):859-71.
8. Allen KJ, Remington BC, Baumert JL, Crevel RW, Houben GF, Brooke-Taylor S, et al. Allergen reference doses for precautionary labeling (VITAL 2.0): clinical implications. J Allergy Clin Immunol. 2014;133(1):156-64.
9. Nowak-Wegrzyn A, Groetch M. Nutritional aspects and diets in food allergy. Chem Immunol Allergy. 2015;101:209-20.
10. Nowak-Wegrzyn A, Fiocchi A. Is oral immunotherapy the cure for food allergies? Curr Opin Allergy Clin Immunol. 2010;10(3):214-9.
11. Meyer R, De Koker C, Dziubak R, Venter C, Dominguez-Ortega G, Cutts R, et al. Malnutrition in children with food allergies in the UK. J Hum Nutr Diet. 2014;27(3):227-35.
12. Yilmaz EA, Soyer O, Cavkaytar O, Karaatmaca B, Buyuktiryaki B, Sahiner UM, et al. Characteristics of children with food protein-induced enterocolitis and allergic proctocolitis. Allergy Asthma Proc. 2017;38(1):54-62.
13. Boyce JA, Assa’a A, Burks AW, Jones SM, Sampson HA, Wood RA, et al. Guidelines for the diagnosis and management of food allergy in the United States: summary of the NIAID-Sponsored Expert Panel Report. Nutrition. 2011;27(2):253-67.
14. Bock SA. Diagnostic evaluation. Pediatrics. 2003;111(6 Pt 3):1638-44.
15. Du Toit G, Roberts G, Sayre PH, Bahnson HT, Radulovic S, Santos AF, et al. Randomized trial of peanut consumption in infants at risk for peanut allergy. N Engl J Med. 2015;372(9):803-13.
16. Grimshaw KE, King RM, Nordlee JA, Hefle SL, Warner JO, Hourihane JO. Presentation of allergen in different food preparations affects the nature of the allergic reaction–a case series. Clin Exp Allergy. 2003 Nov;33(11):1581-5.
Carina Venter, PhD RD, is a Research Associate/Dietitian at Cincinnati Children’s Hospital Medical Center and currently the Chair of the International Network of Dietitians and Nutritionists in Allergy, a member of the AAAAI, BSACI and EAACI. She is a registered dietitian in the United Kingdom, United States and South Africa. She has had numerous publications in international journals, and has authored book chapters and edited a book on Food Hypersensitivity. She was, until recently, working as a Senior Lecturer at the University of Portsmouth, where she was doing research into food allergies and allergy prevention, based at the David Hide Centre on the Isle of Wight.
Carina was a member of the Expert Panel of the National Institutes for Allergy and Infectious Diseases Peanut Allergy Prevention Guidelines, making her the only dietitian to contribute to both US and European food allergy guidelines.
David Fleischer, MD, studied medicine at Emory University School of Medicine. He was a pediatric resident at Johns Hopkins where he also training in Pediatric Allergy/Immunology. He joined the staff of National Jewish Health in Denver in August 2005, where he worked until December 2013. In January 2014, Dr. Fleischer joined the new Allergy Section at Children’s Hospital Colorado (CHCO), where he is currently an Associate Professor of Pediatrics and the University of Colorado Denver School of Medicine.
Dr. Fleischer’s clinical interests include food allergy, eosinophilic gastrointestinal disease, and atopic dermatitis. His research has focused on the natural history of food allergy and novel treatments for food allergy, including oral, sublingual, and epicutaneous immunotherapies. He has been involved in several projects examining the primary prevention of allergy, including as a member of the 2015-16 National Institutes for Allergy and Infectious Diseases (NIAID) Expert Panel that is updating the 2010 NIAID Food Allergy Guidelines on the topic of the Prevention of Peanut Allergy.
Dr. Fleischer has published many peer-reviewed articles, review articles, and book chapters on food allergy and eosinophilic gastrointestinal disease.
{Note, the authors would like to thank those who helped to put their list together: Marion Groetch (USA), Berber Vlieg-Boerstra (The Netherlands), Rosan Meyer (France), Hannah Hunter (UK), Lianne Reeves (UK), Marianne Williams (UK), Paul Turner (UK), Isabel Skypala (UK), Fallon Schultz (USA), Raquel Durban (USA)}