To the Editor: The letter from Dr. Fomon (Amer. J. Dis. Child. 103 :97, 1962) purporting to give the iodine concentrations of various liquid soy formulas is in error. The figures quoted from our report (Arch. Biochem. 93:15, 1961) are the iodine concentrations in the dry rations as prepared for rat feeding trials. These values were determined by actual analysis of the rations fed and represent the quantity of iodine found to be associated with 24 gm. of protein from the indicated source.
The iodine content of Mull-Soy Liquid, as stated on the label, is 30μg. per 100 gm., a level corresponding to 24μg. of iodine per 100 Calories. Mull-Soy Powdered is also fortified by addition of potassium iodide to provide 24μg. of iodine per 100 Calories. Liquid Sobee has been reported to contain iodized salt at a level which provides 3.6μg. of iodine per 120 Calories (Pediatrics 24:856, 1959).