Until recently, endemic goiter was regarded as a deficiency disease due to lack of iodine in food and drinking water. Newer studies have called attention to the importance of positive goitrogenic factors.
The observation of Webster, Clawson and Chesney1 that feeding cabbage to rabbits causes goiter in a short time proved that a dietary factor much more powerful than any iodine deficiency may be responsible for goiter.
During the last few years, another positive goitrogenic agent has been demonstrated. Using lime, calcium chloride or calcium carbonate in conjunction with a diet low in iodine, Tanabe,2 Hellwig,3 Thompson4 and Hibbard5 produced goiters in white rats.
In experiments during 1929 and 1932 I was unable to obtain hyperplasia of the thyroid in white rats by lack of iodine alone. I concluded that iodine deficiency by itself cannot be the essential cause of endemic goiter and that there