Salt
The amount of iodine and the specific iodine compound added to salt varies from country to country. In the United States, the Food and Drug Administration (FDA) recommends [21 CFR 101.9 (c)(8)(iv)] 150 micrograms of iodine per day for both men and women. US iodized salt contains 46–77 ppm (parts per million), whereas in the UK the iodine content of iodized salt is recommended to be 10–22 ppm.
Puppy nutrition
To date, there is little information available about minimum requirements of dietary iodine for developing puppies. However, literature suggests that overdosage of iodine in puppies has deleterious effects on the thyroid gland. High dietary iodine may cause both hypothyroidism and changes in bone metabolism, considering that thyroid hormones are key factors in osteogenesis, as they stimulate osteoblasts, and promote collagen synthesis and mineralization of the osteoid. This is particularly important during juvenile development, as these hormones favor the action of growth hormone (GH) and its facilitator, insulin growth factor-1 (IGF-1) at the osteoplastic level. Hypothyroidism acquired at an early age presents a delay in the maturation and development of the ossification sites of newly-developing bone. It is therefore important to closely monitor the amount of iodine in puppy diets in order to prevent overdosage. The NRC states an adequate intake and recommended allowance of 900 μg/kg (DM) which translates into 220μg/1000 kcal. These values have been shown in multiple studies to be the recommended maximum allowance of iodine that would result in no abnormalities.