Studies on the Relation of Diet to Goiter

Abstract

In extension of previous work on an iodine deficient diet, it is shown that in 125 experimental groups comprising 1021 rats, definite correlations exist between size and iodine content, and between size and dry matter content of the thyroid gland. From the relationship between weight of gland and iodine content, it is deduced that experimental work on the factors which may influence low iodine goiter should be done within the critical range, i.e., an iodine content in the gland of 0.03 per cent or less, dry basis, this probably corresponding to an iodine intake from known sources of 0.4 to 0.3 γ per rat per day, and an iodine content in the ration of 35 parts per billion or less. Since all factors of the environment are difficult to control with certainty, it is suggested that experimental results should be evaluated only in light of simultaneous parallel experiments, and then only if the low iodine controls fall within the critical range. The storage of iodine by young rats during the first 4 weeks of life is not sufficient to prevent goiter when placed for 5 weeks on a low iodine diet. Varying the calcium content of the ration, its Ca: P ratio, and the presence or absence of vitamin D do not significantly affect the degree of goiter produced.