Acute erythroid hypoplasia in malnourished infant squirrel monkeys fed isolated soy protein

Infant squirrel monkeys fed low protein diets using an isolated soy protein develop an acute anemia. To investigate this syndrome, four groups of animals fed diets containing adequate or restricted amounts of casein or soy protein were studied from 1 through 16 weeks of age. The low protein groups, in which growth was prevented by adjustment of the protein content between 2 through 8 weeks, showed no difference in caloric intake or plasma albumin concentrations. However, the low soy group developed a severe anemia (hemoglobin 4 to 7 g/dl) after 4 to 6 weeks of dietary treatment. The anemia was characterized as normocytic, normochromic, and was associated with reduced reticulocyte concentrations. Bone marrow specimens showed an increased myeloid/erythroid ratio due primarily to an absolute erythroid hypoplasia. Juvenile animals fed similar low soy diets did not become anemic. The selective effect of this isolated soy protein, demonstrable only during the transitional period of early infancy, was attributed to the interaction of the malnourished animal with a component of the isolated soy protein per se. The potential role of soy glycoproteins is discussed.