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.
Vegetarian nutrition
One study reported a "potential danger of [iodine] (I) deficiency disorders due to strict forms of vegetarian nutrition, especially when fruits and vegetables grown in soils with low [iodine] levels are ingested." Iodine, however, is usually supplied by iodized salt and other sources in first world countries. Other significant vegetarian sources of iodine include edible seaweed and bread made with dough conditioners.