Q:

12/19/2011
Given soy allergy seems to be a fairly common allergy, I am curious if there is data on whether foods that indicate soy (hydrogenated) are to be avoided? I have had several patients inquire about this designation. I believe it is generally agreed in the allergy community that avoidance of foods containing soybean oil and soy lecithin is not needed. I'd appreciate your insights.

A:

Thank you for your recent inquiry.

About the most definitive opinion you can get in this regard is expressed on two excellent lay websites (one from the Food Allergy and Anaphylaxis Network and the other from the Cleveland Clinic). These are copied for you below, and a link to each site is included.

The rationale for these opinions is based upon studies in the literature as exemplified by the two abstracts that are copied for you below as well (one from the Journal of Allergy and Clinical Immunology and the other from Clinical and Experimental Allergy).

Thank you again for your inquiry and we hope this response is helpful to you.

"Studies have shown that most people with soy allergy can safely eat foods containing soy lecithin and soybean oil"
http://my.clevelandclinic.org/disorders/soy_allergies/hic_soy_allergy.aspx

"Studies show that most soy-allergic individuals may safely eat soybean oil (not cold pressed, expeller pressed, or extruded oil). If you are allergic to soy, ask your doctor whether or not you should avoid soy oil"
http://www.foodallergy.org/page/soy-allergy (Food Allergy and Anaphylaxis Network)

Journal of Allergy and Clinical Immunology
Volume 76, Issue 2, Part 1, August 1985, Pages 242-245
Forty-second Annual Meeting Abstract
We have previously demonstrated that peanut oil is not allergenic to peanut-sensitive individuals. Seven soybean-sensitive patients were enrolled in a double-blind crossover study to determine whether ingestion of soybean oil can induce adverse reactions in such patients. All subjects had histories of systemic allergic reactions (urticaria, angioedema, wheezing, dyspnea, and/or vomiting) after soybean ingestion and had positive puncture skin tests with a 1:20 glycerinated-saline whole soybean extract. Sera from six of the seven subjects were tested by RAST assay for the presence of specific IgE antibodies to soybean allergens. All patients had elevated levels of serum IgE antibodies to the crude soybean extract: binding values ranged from 2.3 to 28.1 times that of a negative control serum. Before the oral challenges, all patients demonstrated negative puncture skin tests to three commercially available soybean oils and to olive oil (control). On four separate days, patients were challenged with the individual soybean oils and olive oil in random sequence. At 30-minute intervals, under constant observation, patients ingested 2, 5, and 8 ml of one of the soybean oils or olive oil contained in 1 ml capsules. No untoward reactions were observed with either the commercially available soybean oils or olive oil. Soybean oil ingestion does not appear to pose a risk to soybean-sensitive individuals.

Antigenicity of the proteins in soy lecithin and soy oil in soybean allergy
1. Awazuhara et alClinical& Experimental Allergy
Volume 28, Issue 12, pages 1559-1564, December 1998
Background
Soy lecithin and soy oil are usually produced from the hexane extract of soybean. Some of the soybean proteins are included in the extract and are therefore present in small amounts in both soy lecithin and soy oil. The antigenicity of the proteins present in defatted soybean has been studied with respect to soybean allergy, but the antigenicity of those found in the extract is yet to be investigated.
Objective: The antigenicity of soy lecithin and soy oil proteins with regard to soybean allergy were investigated.
Methods: The proteins present in soy lecithin and soy oil were determined according to already established method and analysed by SDS-PAGE. The IgE- and IgG4-binding abilities of the soy lecithin proteins were investigated by immunoblotting with sera from 30 soybean-sensitive patients, including seven with a positive challenge test. Immunoblotting of soy oil proteins was performed with the sera from some of these patients.
Results: In 100 g of sample, the soy lecithin and soy oil contained 2.8 mg and 1.4-4.0 ìg of proteins, respectively. The results of SDS-PAGE demonstrated the presence of only three proteins, with molecular weights of about 58-67 kDa in soy oil, and suggested that soy lecithin also contains these proteins. The soy lecithin also contained many proteins besides these. In the soy lecithin, the detection rate of only one protein, with a molecular weight of 31 kDa, by the serum IgE of patients was significantly different compared with controls (detection rate: 40%). The proteins with molecular weights of 58-67 kDa rarely bound to serum IgE. Only one of the patients who presented a positive challenge test had IgE antibodies to soy lecithin proteins. IgG4-binding proteins were found only rarely in soy lecithin. Neither the IgE nor the IgG4 present in the patients' sera reacted to any soy oil protein.
Conclusion: Proteins present in soy lecithin and soy oil have little antigenicity with regard to soybean allergy.

Sincerely,
Phil Lieberman, M.D.

AAAAI - American Academy of Allergy Asthma & Immunology