The development of simple goiter in rabbits, which results when they are fed on a diet consisting chiefly of cabbage (or other Brassica) can be prevented by the feeding of certain fresh plants. Lawn grass, fresh alfalfa, skunk cabbage and steamed cabbage press juice have been found effective. Washing Brassicae with water improves their goiter-producing action, probably by the removal of goiter-preventing substances. The antigoitrous effect of plant juices was found to vary with the amount of reducing substance other than glutathione present. Skunk cabbage press juice, obtained from growing plants during the spring months, contained a large amount of iodine-absorbing material, and was very effective in involuting hyperplastic glands while juice obtained from mature plants in July when the iodine-absorbing material had nearly all disappeared, was quite ineffective. Certain extracts from cabbage administered parenterally, containing the reducing material, also had a marked involuting action on the thyroid. These extracts were practically iodine-free. The substance or substances believed to be responsible are easily soluble in water, ethyl alcohol, aqueous ethyl alcohol and are precipitable by lead acetate at a pH of 0.68–0.70. They are partially destroyed by exposure to air and by steam at 100°. Hexuronic acid isolated by Szent-Györgyi from cabbage, orange juice and suprarenal glands could be the antigoitrous agent. It cannot be glutathione.
The evidence presented indicates that cabbage maturing in the spring and summer months has little goiter-produdag power. Cabbage maturing in the late autumn has much greater goiter-produdng power, although this shows considerable variation in different years. It has not been possible to correlate available meteorological data with these variations.