Systemic allergic reaction following ingestion ofundeclared peanut flour in a peanut-sensitivewomanCrystal McKenna, PhD and Karl C Klontz, MD, MPH

Background: Although peanuts and peanut butter are well recognized as foodallergens, few reports describe allergic reactions associated with eating peanut flour.Objective: To describe an allergic reaction that occurred in a peanut-sensitive

woman who ate undeclared peanut flour that was part of a flavor ingredientcontained in a dry soup mixture, and to estimate the amount of peanut protein thepatient ingested.Methods: The patient was interviewed, medical records from her emergency

room visit were reviewed, and the manufacturer of the soup mix was investigated toascertain the proportion of the soup mix constituted by the undeclared peanut flour.Results: Minutes after ingesting the soup, a 33-year-old woman experienced a

systemic allergic reaction. She was treated successfully in the emergency room withintravenous fluids, corticosteroids, and diphenhydramine. Investigation of the soupmanufacturer revealed that undeclared peanut flour was a component of a flavoringingredient in the soup. Based on the concentration of peanut flour in the flavoring,we estimated the patient ate approximately 45 mg of peanut protein.Conclusions: Inadvertent ingestion of peanut flour by peanut-sensitive individ-

uals may lead to systemic allergic reactions.Ann Allergy Asthma Immunol 1997;79:234–6.

INTRODUCTIONPeanuts are believed to be one of theleading causes of food allergic reac-tions in the United States today,1,2 andthe prevalence of peanut allergy isthought to be increasing in the US3 andin Britain.4 This is significant becausepeanut-allergic individuals who un-knowingly eat peanut-containing foodsmay experience fatal or nearly fatalreactions.4–6Although a specific food item is of-

ten identified as the source of peanutallergen in reports of persons experi-encing peanut-related allergic reac-tions, less information is available re-garding the formulation of peanutspresent in the implicated product. Pre-sumably, most instances of peanut-re-

lated allergic reactions involve con-sumption of parts of the peanut kernels(cotyledons) or peanut butter. A studyof the allergenicity of various peanutproducts using the radioallergosorbenttest inhibition assay reported that pea-nut oil and hydrolyzed peanut proteinwere not allergenic and flour extractmade from peanut hulls was slightlyallergenic.7 In contrast, allergenicitywas demonstrated for eight floursmade from peanut kernels, as well asfor products containing raw or roastedpeanuts or peanut butter.7Peanut flour is used in a wide array

of foods, including breads and bakerygoods, breakfast cereal flakes, meatpatties, snack foods, beverages, icecreams, soups, spreads and frostings,and textured vegetable protein ingredi-ents.8 We describe an allergic reactionin a peanut-sensitive woman who be-came ill shortly after consuming a re-constituted dry pea soup product thatcontained undeclared peanut flour in aflavoring ingredient. The illness came

to the attention of the US Food andDrug Administration (FDA) during aroutine FDA inspection of the manu-facturer of the food product monthsafter the illness occurred. Because noproduct from the implicated lot wasavailable for laboratory testing fromeither the manufacturer or the con-sumer when the FDA learned of theillness, we estimated the amount ofpeanut protein the patient consumed onthe basis of the quantity of soup in-gested and the type and amount ofpeanut flour reported by the manufac-turer to be present in the flavoring.There is little published informationdescribing allergic reactions followingpeanut flour ingestion or the quantityof ingested peanut protein associatedwith such allergic reactions.

METHODSWe interviewed the patient and re-viewed medical records linked to herepisode of illness. To estimate theamount of peanut protein ingested bythe patient, we contacted the manufac-turer of the soup and the manufacturerof the flavoring to obtain details re-garding the quantity and type of peanutflour incorporated into the dry soupmix.

RESULTSCase ReportThe 33-year old woman described herereported a lifelong history of allergy topeanuts, walnuts, and pecans. Inadver-tent ingestion of these items in the pastled to allergic reactions of varying in-tensity depending on the amount of nuteaten. Prior to the present episode, themost severe reaction she ever had oc-curred 16 years earlier shortly aftereating cake containing a raspberry

Both authors work in the Center for FoodSafety and Applied Nutrition, Food and DrugAdministration, 200 C St, SW, Washington, DC20204.Received for publication February 18, 1997.Accepted for publication in revised form

April 4, 1997.

234 ANNALS OF ALLERGY, ASTHMA, & IMMUNOLOGY

blend that had been cooked in peanutsauce; her face became swollen andher fingers and face turned blue,prompting her to seek treatment in anemergency room. In several instancesin which she recognized that she hadjust eaten peanuts or walnuts, she re-portedly spat the food out but never-theless experienced lip swelling anditching of the throat. She also reportsgetting welts on her face if her husbandkisses her there after having recentlyeaten a peanut butter sandwich.In December 1995, the patient expe-

rienced a systemic allergic reaction af-ter eating about a quarter of the con-tents of a single-serve container of drysplit pea soup that she had reconsti-tuted with water to approximately 10fluid ounces. Her previous meal wasthree hours earlier. Prior to eating thesoup, the patient read the product in-gredient label, which listed the follow-ing: dehydrated vegetables (split peas,potatoes, onions, carrots, garlic, cel-ery), yeast extract, salt, spices, and nat-ural smoke flavor. The product expira-tion date was January 1997.Within minutes after ingesting the

soup, the patient experienced a sensa-tion of her throat closing and difficultyswallowing. She developed difficultybreathing, chest tightness, pruritus ofthe hands and face, facial swelling,hives, and a rash over her entire body.Prior to arriving at an emergencyroom, she experienced abdominal dis-comfort, nausea, and an episode ofemesis.The patient took two puffs of Pri-

matene Mist when she experiencedchest tightness and difficult breathing.This provided some relief, but uponarrival in the emergency room she wasflushed and complained of hives andmild abdominal discomfort. On physi-cal examination, the patient was afe-brile, had a blood pressure of 148/90,pulse 86 beats per minute, and a respi-ratory rate of 20 breaths per minute.She had bright red urticaria from headto toes. The oropharynx was withoutswelling. No wheezes, rhonchi, orrales were auscultated. The remainderof the examination was normal.

The patient was treated with intra-venous fluids, corticosteroids, and di-phenhydramine. She felt symptomati-cally improved over the next half hourand was discharged to home with in-structions to consult with her physicianand to obtain self-injectable epineph-rine for possible future use. One monthafter her illness, the patient learnedfrom the manufacturer of the soup thatpeanut flour was a component of theflavoring ingredient. The soup manu-facturer discontinued the use of thepeanut flour-containing flavoring,withdrew undistributed product, andalerted consumers through the FoodAllergy Network, a nonprofit organi-zation that monitors adverse reactionsto foods.

ESTIMATED AMOUNT OFPEANUT PROTEIN INGESTEDThe manufacturer of the dry split peasoup mix reported that of the 1,358.3lb of dry soup mix, 47.3 lb consisted ofthe flavoring ingredient, and approxi-mately 30% of the flavoring ingredientwas partially defatted peanut flour. Asingle-serving container of dry soupmix weighing 58 g, therefore, con-tained about 603 mg of peanut flour.The proportion of peanut flour com-posed of protein varies from approxi-mately 60% for fully defatted peanutflour to 30% for partially defattedflour.8,9 Assuming 30% of the peanutflour in the dry soup mix was protein,each single-serving soup mix containercontained approximately 181 mg ofpeanut protein. Given that about onequarter of the contents of a single-serve container of soup mix was con-sumed, we estimate that the patientingested approximately 45 mg of pea-nut protein.

DISCUSSIONSeveral factors suggest that peanutflour contained in the soup flavoringingredient was responsible for trigger-ing the symptoms in the patient de-scribed here. First, the soup was theonly food consumed immediately priorto onset of symptoms, and the flavor-ing was the only ingredient in the soupknown to contain peanut components.

The only other food consumed by thepatient earlier that day had been eatenthree hours previously, and she wasasymptomatic until she ate the soup.Additionally, the patient, having expe-rienced peanut-associated allergic re-actions previously in her life, recog-nized the symptoms as the kindproduced by the ingestion of peanuts.This prompted her to call the manufac-turer of the soup to investigate the pos-sibility that peanuts were included inthe ingredients, even though peanutswere not listed on the soup’s ingredientlist. Finally, the plausibility of peanutflour acting as the allergen in this pa-tient’s illness is supported by a previ-ous study that used the radioallergosor-bent test inhibition assay to show the invitro allergenicity of eight peanutflours prepared from the cotyledons ofthe peanut.7Ample evidence suggests that

minute amounts of ingested peanut aresufficient to trigger clinically apparentallergic reactions, including fatal ornearly fatal reactions. For example,Ewan4 reported that a “trace” amountof ingested peanut produced severe la-ryngeal edema and respiratory arrest ina 31-year-old man. Fatal peanut-in-duced anaphylaxis has been describedin patients following consumption oftwo bites of chili containing peanutbutter, one peanut-containing cookie,or a single bite of a peanut-containingcake.6 Additionally, peanut-sensitiveindividuals have reportedly experi-enced generalized hives or wheezingsimply by being near peanuts10 orpresent when a peanut butter-contain-ing jar was opened.11The potential for peanuts to be con-

sumed unknowingly by peanut-allergicindividuals is facilitated by several fac-tors. First, peanuts or peanut butter isused in a wide array of commercialproducts. For example, more than 60%of the “nuts” used in candies in theUnited States are peanuts; no other fla-vor ingredient, except chocolate, isused as broadly in confections.8 Addi-tionally, insufficient product labelingor mislabeling can obscure the pres-ence of peanuts. Finally, food itemsthat are not intended to include peanuts

VOLUME 79, SEPTEMBER, 1997 235

may contain peanuts as a result of con-tamination during the manufacturingprocess, particularly in processingplants in which production switchesfrom one food product to another.11,12The patient described here reported

taking inhaled epinephrine when sheexperienced chest tightness at home.Medical records from her visit to theemergency room, however, indicatethat epinephrine was omitted from thetreatment regimen; this was confirmedin our interview of the patient. Inhaledepinephrine, with or without oral anti-histamines, is not appropriate as a sin-gle therapeutic agent in moderate orsevere anaphylaxis.6 In a report sum-marizing fatal and nearly fatal anaphy-lactic reactions to food in children andadolescents, Sampson et al5 underscorethe beneficial role of parenteral epi-nephrine. In that study, there were nodeaths among patients who receivedepinephrine before severe respiratorysymptoms developed, whereas all thepatients with nonfatal reactions re-ceived epinephrine before or withinfive minutes of the development ofsevere symptoms. Food-allergic per-sons should be provided with epineph-rine-containing syringes and instructedhow to self-administer epinephrine atthe first sign of allergic reaction.6The Food, Drug, and Cosmetic Act

requires, in virtually all cases, a com-plete listing of all the ingredients of afood. One important exemption, how-ever, is that spices, flavorings, and col-orings may be declared collectivelywithout naming each ingredient.13 Ep-isodes of illness such as the one de-scribed here, ie, the occurrence of an

allergic reaction linked to ingesting un-declared peanut flour present in a fla-voring, have prompted the FDA toconsider requiring the declaration ofknown allergens in spices, flavors, andcolors.14 There is strong biologic justi-fication for this requirement in view ofmounting evidence that minuteamounts of food allergens are capableof causing fatal or nearly fatal reac-tions in sensitive individuals. At thesame time, it is critical that food man-ufacturers take all steps necessary toeliminate occurrences of cross contam-ination whereby recognized food aller-gens, such as peanuts, eggs, tree nuts,etc, are inadvertently introduced intoproducts that are not intended to con-tain such allergens. In the meantime,the FDA continues to assist food man-ufacturers in expediting recalls relatedto undeclared allergens in foods. Forexample, during fiscal year 1995, theFDA assisted in 60 recalls of foodproducts resulting from the presence ofundeclared allergens; 46 of the recalledproducts contained undeclared egg (37of these were in chocolate candiesmanufactured by one company), 6 un-declared peanut, and the remaining 8undeclared tree nuts or milk.

REFERENCES1. Sampson HA, Metcalfe DD. Food al-lergies. JAMA 1992;268:2840–4.

2. Bock SA, Atkins FM. Patterns of foodhypersensitivity during sixteen yearsof double-blind, placebo-controlledfood challenges. J Pediatr 1990;117:561–7.

3. Sampson HA. Managing peanut al-lergy. Br Med J 1996;312:1050–1.

4. Ewan PW. Clinical study of peanutand nut allergy in 62 consecutivepatients: new features and associa-tions. Br Med J 1996;312:1074–8.

5. Sampson HA, Mendelson L, Rosen JP.Fatal and near-fatal anaphylactic reac-tions to food in children and adoles-cents. N Engl J Med 1992;327:380–4.

6. Yunginger JW, Sweeney KG, SturnerWQ, et al. Fatal food-induced anaphy-laxis. JAMA 1988;260:1450–2.

7. Nordlee JA, Taylor SL, Jones RT,Yunginger JW. Allergenicity of vari-ous peanut products as determined byRAST inhibition. J Allergy Clin Im-munol 1981;68:376–82.

8. Lusas EW. Food uses of peanut pro-tein. J Am Oil Chem Soc 1979;56:425–30.

9. Beuchat LR, Cherry JP, Quinn MR.Physicochemical properties of peanutflour as affected by proteolysis. J Ag-ric Food Chem 1975;23:616–20.

10. Fries JH. Peanuts: Allergic and otheruntoward reactions. Ann Allergy 1982;48:220–6.

11. Yunginger JW, Gauerke MB, JonesRT, et al. Use of radioimmunoassay todetermine the nature, quantity andsource of allergenic contamination ofsunflower butter. J Food Prot 1983;46:625–8.

12. Kemp SF, Lockey RF. Peanut anaphy-laxis from food cross-contamination.JAMA 1996;275:1636–7.

13. Food, Drug and Cosmetic Act. Section403 [1].

14. U.S. Food and Drug Administration.Label declaration of allergenic sub-stances in foods. FDA Notice to Man-ufacturers. June 10, 1996.

No reprints are available

236 ANNALS OF ALLERGY, ASTHMA, & IMMUNOLOGY