A goiter is an enlargement of the thyroid gland.
 The thyroid gland is located at the base of the neck.
 It secretes a fluid, the hormone thyroxin, which s made from iodine and tyrosine, an amino acid.
The thyroid, through the thyroxin hormone, regulates metabolism or the burning of food, growth and body temperature and influences mental and emotional balance; it is also a factor in the function of the reproductive system.
Thyroid disorders are caused by an inadequate intake of iodine, resulting in insufficient thyroxin production, or a disorder elsewhere in the body that requires more thyroxin than the gland can manufacture.
Goiter may be caused by a lack of iodine in the diet, inflammation of the thyroid gland due to infection, or under - or overproduction of thyroxin by the thyroid gland.
Symptoms of goiter are a swelling at the base of the neck, hoarseness, change in the rate of metabolism, and in extreme cases, difficulty in swallowing and breathing.
  Treatment of goiter varies with the cause.
 If goiter is due to an iodine deficiency, increasing the intake of iodine will prevent further enlargement of the gland, and in some cases, reduce its size.
Vitamin A is necessary for the proper metabolism of iodine; this vitamin is also important for the proper functioning of the pituitary gland, which secretes a substance that regulates the thyroid.
Tyrosine can not be used without vitamin B6 and C.
Vitamin E increases the absorption of iodine.
The use of iodized salt has helped to eliminate goiter in many places where iodine does not occur naturally in foods.
Kelp is an excellent source of iodine, low in sodium, and is better retained by the body than potassium iodide.