Soybeans and other legumes are an important source of protein in human and animal diets, but are deficient in the essential amino acid methionine. Many domestic animals are fed soybean meal diets and require supplements to meet their dietary methionine needs. To improve the nutritional quality of soybeans, researchers at Pioneer Hi-Bred International developed a line of genetically engineered soybeans that produces a methionine-rich protein from Brazil nuts.

Because Brazil nut is a known food allergen, Pioneer investigated the potential of increased allergenicity in the new soybean, as recommended by the FDA. The study, funded entirely by Pioneer Hi-Bred International, was conducted by two food scientists at the University of Nebraska, two scientists from Pioneer R&D, and a medical researcher at the W.S. Middleton Memorial Veterans Affairs Hospital/University of Wisconsin, Madison. Using blood and skin-prick tests, the researchers determined that at least some persons with a hypersensitivity to Brazil nut were also allergic to the genetically engineered soybean. Although this variety was developed primarily for animal feed, Pioneer felt that it could not adequately prevent these soybeans from entering the human food supply, and as a result of these tests, Pioneer never marketed this line of soybeans.
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Nordlee, J.S., Taylor, S., Townsend, J., Thomas, L., Bush, R. 1996. Identification of a brazil-nut allergen in transgenic soybeans. New England J.Med. 334:688-692.