By Mark Messina, PhD, MS
The U.S. Food Allergen Labeling & Consumer Protection Act (FALCPA) mandates labeling of all ingredients derived from commonly allergenic foods. In the United States, eight foods have been identified as the most frequent human food allergens, accounting for 90 percent of food allergies. These foods are milk, eggs, fish, crustacea, wheat, peanuts, tree nuts and soy.1,2 However, these foods are not equally allergenic—in fact, soy protein allergies are relatively uncommon.3 Being allergic to soy protein is much less common than being allergic to milk or peanuts.4,5
Importantly, the FALCPA exempts highly refined oils from these labeling provisions because highly refined soybean, peanut and sunflower seed oils have been clinically documented to be safe for consumption by individuals allergic to the source food.6-9Soy is viewed similarly in Europe, where soy protein is classified as one of the 14 most common foods that induce allergic reactions, yet fully refined soybean oil is exempt from labeling.10
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.11 However, it is extremely difficult to quantify the protein content of oil. Attempts to do so indicate that crude oils contain about 100-300 mg/kg, whereas fully refined oils contain at least 100 times less.11 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.12 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.11,13-15 Analytical data from Rigby et al.16on 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.16
There have been a few cases where soybean oil elicited an allergic response, but these instances followed intravenous infusion of an emulsion containing soybean oil, which seems far removed from typical consumption.14,17,18 There is also one 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.19 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 addition to the clinical studies cited here showing that highly refined soybean does not elicit an allergic response, circumstantial evidence supporting the clinical results comes from the work of the Swedish National Food Administration. Since 1994, this group has been recording and investigating all cases of fatal and severe reactions to foods.20,21 While soy protein featured in about 25 percent of the reported cases (compared to ~33 percent for peanuts), none implicated soybean oil, or a product containing soybean oil as the only source of soy.
- Food and Agriculture Organization of the United Nations (1995) Report of the FAO Technical Consultation on Food Allergies. Rome, Italy.
- Food Allergen Labeling and Consumer Protection Act of 2004 (Public Law 108-282, Title II) http://www.fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/Allergens/ucm106187.htm.
- Katz Y, Gutierrez-Castrellon P, Gonzalez MG, Rivas R, Lee BW, Alarcon P. A comprehensive review of sensitization and allergy to soy-based products. Clin Rev Allergy Immunol. 2014;46:272-81.
- Vierk KA, Koehler KM, Fein SB, Street DA. Prevalence of self-reported food allergy in American adults and use of food labels. J Allergy Clin Immunol. 2007;119:1504-10.
- Nwaru BI, Hickstein L, Panesar SS, Roberts G, Muraro A, Sheikh A. Prevalence of common food allergies in Europe: a systematic review and meta-analysis. Allergy. 2014;69:992-1007.
- Bush RK, Taylor SL, Nordlee JA, Busse WW. Soybean oil is not allergenic to soybean-sensitive individuals. J Allergy Clin Immunol. 1985;76:242-5.
- Halsey AB, Martin ME, Ruff ME, Jacobs FO, Jacobs RL. Sunflower oil is not allergenic to sunflower seed-sensitive patients. J Allergy Clin Immunol. 1986;78:408-10.
- Hourihane JO, Bedwani SJ, Dean TP, Warner JO. Randomised, double blind, crossover challenge study of allergenicity of peanut oils in subjects allergic to peanuts. BMJ. 1997;314:1084-8.
- Martin-Hernandez C, Benet S, Obert L. Determination of proteins in refined and nonrefined oils. J Agric Food Chem. 2008;56:4348-51.
- European Commission Directive 2007/68/EC of 27th November 2007.
- Crevel RW, Kerkhoff MA, Koning MM. Allergenicity of refined vegetable oils. Food Chem Toxicol. 2000;38:385-93.
- Moneret-Vautrin DA, Kanny G. Update on threshold doses of food allergens: implications for patients and the food industry. Curr Opin Allergy Clin Immunol. 2004;4:215-9.
- Errahali Y, Morisset M, Moneret-Vautrin DA, et al. Allergen in soy oils. Allergy. 2002;57:648-9.
- Moneret-Vautrin DA, Morisset M, Flabbee J, Kanny G, Kirch F, Parisot L. Unusual soy oil allergy. Allergy. 2002;57:266-7.
- Renaud C, Cardiet C, Dupont C. Allergy to soy lecithin in a child. J Pediatr Gastroenterol Nutr. 1996;22:328-9.
- 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;59:1752-9.
- Andersen HL, Nissen I. [Presumed anaphylactic shock after infusion of Lipofundin]. Ugeskr Laeger. 1993;155:2210-1.
- Hiyama DT, Griggs B, Mittman RJ, Lacy JA, Benson DW, Bower RH. Hypersensitivity following lipid emulsion infusion in an adult patient. JPEN J Parenter Enteral Nutr. 1989;13:318-20.
- Palm M, Moneret-Vautrin DA, Kanny G, Denery-Papini S, Fremont S. Food allergy to egg and soy lecithins. Allergy. 1999;54:1116-7.
- Foucard T, Edberg U, Malmheden Yman I. [Fatal and severe food hypersensitivity. Peanut and soya underestimated allergens]. Lakartidningen. 1997;94:2635-8.
- Foucard T, Malmheden Yman I. A study on severe food reactions in Sweden--is soy protein an underestimated cause of food anaphylaxis? Allergy. 1999;54:261-5.