Studies on soybean factors which produced goiter in rats.

The goitrogenicities of various preparations obtained from soybean were studied using rats. Thyroid weight, 131I uptake and the ratio of 131I-monoiodotyrosine to 131I-diiodotyrosine of the gland in rats fed the preparation was measured to determine the activity of these preparations. It was resulted that the group of rats receiving the curd had the most hypertrophied thyroid, the enlargement being equal to that in the group of these receiving soybean in the 8 weeks' feeding experiment. No difference on the content of iodine were found with the various diet preparations. The proteolytic digestion of soybean curd did not eliminate the goitrogenic property, thus, the goitrogen seems not to be a protein or peptide-like substance.