Many salt shakers read; “This salt does not provide iodine, a necessary nutrient.” This leads to the question: what is iodine? What makes it a necessary nutrient? The main use of iodine in the body is the synthesis of hormones in the thyroid gland. When the thyroid does not receive enough of this necessary nutrient, it will be unable to produce hormones. This is known as hypothyroidism. Iodine deficiency is one of the most common causes of hypothyroidism. Iodine deficiency can obviously be caused by a lack of iodine intake, however substances such as halogens can also reduce iodine in the body. Overcoming iodine deficiency could be as easy as eating vegetables grown in iodine-rich soil or using iodized salt. Some people need iodine supplements. Hypothyroidism can be caused by many substances in the environment or by an iodine deficiency, but it can be combated by increasing iodine intake. The thyroid is often called the most important gland in the body. This is because it produces the hormones thyroxine (T4), triiodothyronine (T3) and calcitonin. These hormones regulate a variety of tasks including cellular activity, brain function, metabolism, the immune system, and heart stimulation. (Friedman) All of this may be taken for granted, but it is very important to take care of your thyroid. To produce these vital hormones, the thyroid needs iodine. The follicular cells of the thyroid trap iodine (as Iodide, I-) by absorbing it from the blood in exchange for Na+. Subsequently, the thyroid collects iodine, concentrating it 30-50 times more than in the blood. The iodide is then used to synthesize T4 and T3, and these hormones are released into the bloodstream. (Nussey) Without iodine, none of this would be possible...... half of the article ......t.Du Toit, J., and NH Casey. “Iodine as a Alleviator of Bromine Toxicity in the Thyroid, Liver, and Kidneys of Broiler Chickens.” Livestock Science 4.3 (2012): 269-74. Print.Sang, Zhongna. “Exploring the safe upper level of iodine intake in euthyroid Chinese adults: a randomized double-blind study.” The American Journal of Clinical Nutrition (2011): n. page Print."Avoid this if you want to keep your thyroid healthy." Mercola.com. Np, nd Web. January 12, 2014. Nussey, Stephen and Saffron A. Whitehead. Endocrinology: an integrated approach. Oxford, UK: Bios, 2001. Print.Evert, Alison. "Iodine in the Diet: MedlinePlus Medical Encyclopedia." United States National Library of Medicine. US National Library of Medicine, 18 February 2013. Web. 09 January 2014. "Hypothyroidism (underactive thyroid)." Mayoclinic. Np, nd Web. 12 January. 2014.