Soybeans contain growth-promoting and heart-protecting proteins. To boost these benefits, the United Soybean Board, an industry group based in Chesterfield, Mo., has been pushing growers to develop soy with even higher protein yields. A new study suggests that such an achievement might come at a serious price: a reduction in the protein's quality.
A limitation of soy protein has always been that it contains too few sulfur-based amino acids, which are particularly important for growing children and for livestock. That's why soy-based feed and foods are typically supplemented with an expensive sulfur-based amino acid such as methionine, explains Hari B. Krishnan of the U.S. Agricultural Research Service plant genetics unit in Columbia, Mo.