Background: Soy lecithin is widely used as an emulsifier in processed foods, pharmaceuticals and cosmetics. Soy lecithin is composed principally of phospholipids; however, it has also been shown to contain IgE-binding proteins, albeit at a low level. A few clinical cases involving allergic reactions to soy lecithin have been reported. The purpose of this investigation is to better characterize the IgE-binding proteins typically found in lecithin. Methods: Soy lecithin proteins were isolated following solvent extraction of lipid components and then separated on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The separated lecithin proteins were immunoblotted with sera from soy-sensitive individuals to determine the pattern of IgE-binding proteins. The identity of IgE-reactive bands was determined from their N-terminal sequence. Results: The level of protein in six lecithin samples obtained from commercial suppliers ranged from 100 to 1,400 ppm. Lecithin samples showed similar protein patterns when examined by SDS-PAGE. Immunoblotting with sera from soy-sensitive individuals showed IgE binding to bands corresponding to 7, 12, 20, 39 and 57 kD. N-terminal analysis of these IgE-binding bands resulted in sequences for 3 components. The 12-kD band was identified as a methionine-rich protein (MRP) and a member of the 2S albumin class of soy proteins. The 20-kD band was found to be soybean Kunitz trypsin inhibitor. The 39-kD band was matched to a soy protein with unknown function. Conclusions: Soy lecithin contains a number of IgE-binding proteins; thus, it might represent a source of hidden allergens. These allergens are a more significant concern for soy-allergic individuals consuming lecithin products as a health supplement. In addition, the MRP and the 39-kD protein identified in this study represent newly identified IgE-binding proteins.

Wilson TA, Meservey CM, Nicolosi RJ: Soy lecithin reduces plasma lipoprotein cholesterol and early atherogenesis in hypercholesterolemic monkeys and hamsters: Beyond linoleate. Atherosclerosis 1998;140:147–153.
Porras O, Carlsson B, Fallstrom SP, Hanson LA: Detection of soy protein in lecithin, margarine and, occasionally, soy oil. Int Arch Allergy Appl Immunol 1985;78:30–32.
Flider FJ: The manufacture of soybean lecithins; in Szuhaj BF, List GR (eds): Lecithins. Champaign, American Oil Chemists’ Society, 1985, pp 21–37.
Awazuhara H, Kawai H, Baba M, Matsui T, Komiyama A: Antigenicity of the proteins in soy lecithin and soy oil in soybean allergy. Clin Exp Allergy 1998;28:1559–1564.
Muller U, Weber W, Hoffman A, Franke S, Lange R, Vieths S: Commercial soybean lecithins: A source of hidden allergens? Z Lebensm Unters Forsch A 1998;207:341–351.
Sampson HA, Burks AW: Mechanisms of food allergy. Ann Rev Nutr 1996;16:161–177.
Bush RK, Hefle SL: Food allergens. Crit Rev Food Sci Nutr 1996;36(suppl):S119–S163.
Bush RK, Schroeckenstein D, Meier-Davis S, Balems J, Remple D: Soybean flour asthma: Detection of allergens by immunoblotting. J Clin Immunol 1988;82:251–255.
Perdu LF, Prevost A, Vallerand H, Cossart C, Passemard F: Baker’s asthma related to soybean lecithin exposure. Allergy 1994;49:159–162.
Renaud C, Cardiet C, Dupond C: Allergy to soy lecithin in a child. J Pediatr Gastroenterol Nutr 1996;22:328–329.
Fine SR: Possible reactions to soya lecithin in aerosols. J Allergy Clin Immunol 1991;87:600.
Palm M, Monertet-Vautrin DA, Kanny G, Denery-Papini S, Fremont S: Food allergy to egg and soy lecithins. Allergy 1999;54:1116–1117.
Lory OH, Rosebrough NJ, Farr AL, Randall RJ: Protein measurement with the Folin phenol reagent. J Biol Chem 1951;193:265–275.
Loroz LA, Yang WH: Kunitz soybean trypsin inhibitor. A specific allergen in food anaphylaxis. N Engl J Med 1980;302:1126–1128.
Burks AW, Cockrell G, Connaughton C, Guin J, West A, Helm R: Identification of peanut agglutinin and soybean trypsin inhibitor as minor legume allergens. Int Arch Allergy Immunol 1994;105:143–149.
Revilleza MJ, Galvez AF, Krenz DC, De Lumen BO: An 8 kDa methionine-rich protein (MRP) from soybean (Glycine max) cotyledon: Identification, purification and N-terminal sequence. J Agric Food Chem 1996;44:2930–2935.
Odani S, Koide T, Ono T: Amino acid sequence of a soybean (Glycine max) seed polypeptide having a poly(L-aspartic acid) structure. J Biol Chem 1987;262:10502–10505.
Rico M, Bruix M, Gonzalez C, Monsalve R, Rodriguez R: 1H NMR assignment and global fold of napin Bnlb, a representative 2S albumin seed protein. Biochemistry 1996;35:15672–15682.
Gayler KR, Kolivas S, McFarlane AJ, Lilley GG, Baldi M, Blagrove RJ, Johnson ED: Biosynthesis, cDNA and amino acid sequences of a precursor of conglutin delta, a sulfur-rich protein from Lupinus angustifolius. Plant Mol Biol 1999;15:879–893.
Kleber-Janke T, Crameri R, Appenzeller U, Schlaak M, Becker W-M: Selective cloning of peanut allergens, including profilin and 2S albumins by phage display technology. Int Arch Allergy Immunol 1999;119:265–274.
Ogawa T, Bando N, Tsuji H, Okajima H, Nishikawa K, Sasaoka K: Investigation of the IgE-binding proteins in soybeans by immunoblotting with the sera of the soybean-sensitive patients with atopic dermatitis. J Nutr Sci Vitaminol (Tokyo) 1991;37:555–565.
Herian A, Taylor S, Bush RK: Identification of soybean allergens by immunoblotting with sera from soy-allergic adults. Int Arch Allergy Appl Immunol 1990;92:193–198.
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.