If a patient has hyperthyroidism, a condition in which the thyroid overproduces the hormone that controls metabolism, foods rich in iodine, such as salmon, are harmful, according to WebMD. However, salmon is a useful food to consume for those with low thyroid function, according to WholeHealthMD.com.
Other sources of food rich in iodine are seafood such as fish, shrimp and seaweed. Most people in the United States get enough iodine in their diet through iodized table salt, according to WebMD. Sea salts, and salts in packaged and processed foods, typically aren't iodized and therefore do not enhance the function of the thyroid.