The Effect of Enhanced Iodine Intake on Growth and on the Thyroid Glands of Normal and Goitrous Rats

The presence of 265 micrograms of iodine per kilogram in an otherwise well-balanced diet is sufficient to protect growing rats from iodine deficiency as evidenced by changes in the thyroid gland. Further enhancement of the iodine content of the diet either by sodium iodide or dried haddock, up to forty times the amount present in the original, does not significantly affect the weight or dry matter content of the glands, but may possibly bring about a slight increase in the iodine content. Iodine in the diet, up to 50 to 100 times the minimal protective dose, does not affect growth or utilization of food for growth. If iodine enriched diets are fed to rats with enlarged and hyperplastic thyroids, the gland tends to return to normal weight and dry matter content, but such glands can store more iodine than normal ones.