Allergenicity and antigenicity of fenugreek (Trigonella foenum-graecum) proteins in foods

Background

Fenugreek is an ingredient in Indian-style spiced foods. Reports of adverse reactions reflect a trend toward a more international cuisine. Fenugreek allergy has not been systematically investigated so far.

Objective

Study the allergenicity and antigenicity of fenugreek proteins using patient sera and a newly developed polyclonal antifenugreek antibody.

Methods

Allergenic fenugreek proteins were identified by immunoblotting, using sera from 29 patients with specific IgE to peanut and other legumes. In addition, 2 patients were evaluated by skin prick test and open food challenge with native fenugreek powder. Spiced and flavored food products were analyzed for fenugreek by semiquantitative IgE and IgG immunoblotting.

Results

High levels of specific IgE to both peanut and fenugreek were seen in most sera. Fenugreek sensitization is believed to be a consequence of cross-reactivity in patients with peanut allergy. Primary fenugreek allergy was suspected in only 1 case. The fenugreek dose eliciting objective symptoms was about 2 mg in the open food challenge. Major fenugreek allergens were identified at 50, 52, and 74 kd and peanut proteins at 22, 36, and 40 kd. A specific polyclonal antifenugreek antibody was found suitable for food analysis. In a food survey, about 1/3 of the fenugreek-containing products were labeled correctly.

Conclusion

Fenugreek seed powder, an ingredient in spiced foods, contains several potential allergens. There is evidence for a high rate of cross-reactivity to peanut.

Key words: Allergen, allergenicity, antigenicity, cross-reactivity, fenugreek, food, IgE, immunoblotting, legumes, open food challenge, peanut, polyclonal antibody, skin prick tests

Abbreviation used: NorFoodAllergyReg, Norwegian Register and Reporting System for Severe Allergic Reactions to Food, RT, Room temperature, SPT, Skin prick test