The U.S. Food Allergen Labeling & Consumer Protection Act (FALCPA) mandates labeling of all ingredients derived from commonly allergenic foods. In the U.S., 8 foods, commonly referred to as the Big 8, have been identified as the most frequent human food allergens; accounting for 90% of food allergic reactions among Americans. These foods are milk, eggs, fish, crustacea, wheat, peanuts, tree nuts, and soy.1,2 However, the prevalence of allergy for each of these foods varies markedly. North American surveys published over the past 10 years show that among the Big 8, the prevalence of soy allergy is lower than the prevalence of the other 7 foods.3-6
Importantly, the FALCPA exempts highly refined oils from these labeling provisions. Soybean oil is viewed similarly in Europe, where soy protein is classified as one of the 14 most common foods that induce allergic reactions.7 The reason for these exceptions is that highly refined soybean, as well as peanut and sunflower seed, oils have been clinically documented to be safe for consumption by individuals allergic to the source food.8-11 For example, Taylor et al.12 tested the ability of a mixture of 4 soybean oils with the highest protein level from a group of 30 highly refined oils obtained from 30 different worldwide processors in a group of 28 soy protein-allergic individuals. Study participants consumed increasing doses of 1, 5, and 10g soybean oil (test material) and canola oil (control material) in a double-blind placebo-controlled food challenge. No untoward reactions were encountered to either soybean or canola oils.
The process of commercially refining soybean oil involves extraction with hot solvents, bleaching, and deodorization, which serve to eliminate almost all soy protein (and thus allergens) from the oil.13 It is, however, difficult to quantify the protein content of oil. Attempts to do so indicate that crude oils contain about 100–300mg/kg, whereas fully refined oils contain at least 100 times less.13 This difference explains the lack of reaction observed in response to ingesting highly refined oils, unlike ingesting unrefined or partially refined culinary oils, which have been found to elicit allergic reactions in sensitized individuals.14 While highly refined soybean oil does contain residual soy protein, the residue levels are extremely low—too low to elicit an allergic response in nearly all cases.13,15-17 Analytical data from Rigby et al.18 on cumulative threshold doses for soy protein suggest that even the most sensitive individuals would need to consume at least 50g of highly refined oil to experience subjective symptoms.18
There have been a few cases where soybean oil elicited an allergic response, but these cases followed intravenous infusion of an emulsion containing soybean oil, which seems far removed from typical consumption.16,19,20 There is also 1 unusual case of a possible soy oil-induced allergy after an infant was fed exclusively on an amino acid-based formula containing a soybean oil-based component.21 The circumstances of exposure in this exceptional case are unusual and the association with the soybean oil component of the formula was somewhat speculative.
In contrast to highly refined soybean oil, lecithin derived from soybeans does require labeling (a few exemptions have been granted) even though nearly all the protein is removed in the soy lecithin manufacturing process. According to Steve L. Taylor, PhD, and Joe L. Baumert, PhD, Food Allergy Research and Resource Program, University of Nebraska, soy lecithin does not contain sufficient soy protein residues to provoke allergic reactions in the majority of soy-allergic consumers.22 On the other hand, these authors note there is “the possibility that some of the more sensitive soybean-allergic consumers might react to ingestion of soybean lecithin.” More research on the allergenicity of soy lecithin is warranted.
Editor’s note: Portions of this article are excerpts from a 2017 Soy Connection article.
1. Food and Agriculture Organization of the United Nations (1995) Report of the FAO Technical Consultation on Food Allergies. Rome, Italy.
2. Food Allergen Labeling and Consumer Protection Act of 2004 (Public Law 108-282, Title II) http://www.fda.gov/Food/GuidanceRegulation/GuidanceDocuments
3. McGowan EC, Peng RD, Salo PM, et al. Changes in food-specific IgE Over time in the National Health and Nutrition Examination Survey (NHANES). The journal of allergy and clinical immunology In practice. 2016;4(4):713-20.
4. Verrill L, Bruns R, Luccioli S. Prevalence of self-reported food allergy in U.S. adults: 2001, 2006, and 2010. Allergy Asthma Proc. 2015;36(6):458-67.
5. Gupta RS, Warren CM, Smith BM, et al. Prevalence and severity of food allergies among US adults. JAMA Netw Open. 2019;2(1):e185630.
6. Soller L, Ben-Shoshan M, Harrington DW, et al. Overall prevalence of self-reported food allergy in Canada. J Allergy Clin Immunol. 2012;130(4):986-8.
7. European Commission Directive 2007/68/EC of 27th November 2007.
8. Bush RK, Taylor SL, Nordlee JA, et al. Soybean oil is not allergenic to soybean-sensitive individuals. J Allergy Clin Immunol. 1985;76(2 Pt 1):242-5.
9. Halsey AB, Martin ME, Ruff ME, et al. Sunflower oil is not allergenic to sunflower seed-sensitive patients. J Allergy Clin Immunol. 1986;78(3 Pt 1):408-10.
10. Hourihane JO, Bedwani SJ, Dean TP, et al. Randomised, double blind, crossover challenge study of allergenicity of peanut oils in subjects allergic to peanuts. BMJ. 1997;314(7087):1084-8.
11. Martin-Hernandez C, Benet S, Obert L. Determination of proteins in refined and nonrefined oils. J Agric Food Chem. 2008;56(12):4348-51.
12. Taylor SL, Nordlee JA, Sicherer SH, et al. Soybean oil is not allergenic to soybean-allergic individuals. J Allergy Clin Immunol. 2004;113(2):S99.
13. Crevel RW, Kerkhoff MA, Koning MM. Allergenicity of refined vegetable oils. Food Chem Toxicol. 2000;38(4):385-93.
14. Moneret-Vautrin DA, Kanny G. Update on threshold doses of food allergens: implications for patients and the food industry. Current opinion in allergy and clinical immunology. 2004;4(3):215-9.
15. Errahali Y, Morisset M, Moneret-Vautrin DA, et al. Allergen in soy oils. Allergy. 2002;57(7):648-9.
16. Moneret-Vautrin DA, Morisset M, Flabbee J, et al. Unusual soy oil allergy. Allergy. 2002;57(3):266-7.
17. Renaud C, Cardiet C, Dupont C. Allergy to soy lecithin in a child. J Pediatr Gastroenterol Nutr. 1996;22(3):328-9.
18. Rigby NM, Sancho AI, Salt LJ, et al. Quantification and partial characterization of the residual protein in fully and partially refined commercial soybean oils. J Agric Food Chem. 2011;59(5):1752-9.
19. Andersen HL, Nissen I. [Presumed anaphylactic shock after infusion of Lipofundin]. Ugeskr Laeger. 1993;155(28):2210-1.
20. Hiyama DT, Griggs B, Mittman RJ, et al. Hypersensitivity following lipid emulsion infusion in an adult patient. JPEN J Parenter Enteral Nutr. 1989;13(3):318-20.
21. Palm M, Moneret-Vautrin DA, Kanny G, et al. Food allergy to egg and soy lecithins. Allergy. 1999;54(10):1116-7.22. Taylor SL, Baumert JL. Allergenicity of soybean lecithin. Expert opinion statement Food Allergy Research & Resource Program University of Nebraska. 2017.