To increase the effectiveness of your upcoming radioactive iodine therapy, you may be prescribed a low iodine diet. Iodine is used in the care and feeding of animals and as a stabilizer and/or safety element in food processing. Therefore, it may be found in varying amounts in all food and beverages. The highest sources (and those to be avoided) are iodized salt, grains and cereals, some breads, fish from the sea, shellfish, beef, poultry, pudding mixes, milk and milk products.