Symptoms of low iodine include a swollen neck, trouble ovulating and high blood pressure during pregnancy. Iodine deficiency in pregnant mothers also increases the risk of mental retardation for their babies, according to WebMD. The thyroid gland needs iodine to produce hormones.
Thyroid hormones are essential for keeping the heart, brain and other organs functioning correctly, states the American Thyroid Association. Since humans aren't able to make iodine on their own, they must incorporate it into their diet. Cheese, soy milk and frozen yogurt all contain iodine. Ocean-based plants and animals, such as seaweed and saltwater fish, are also significant sources of this element.