SF Fig. 2.16. Woman with goiter, an enlarged thyroid gland, in India
Image courtesy of Dr. J.S. Bhandari from Wikipedia
Title
Weird Science: Salt Fortification and Additives
NGSS Disciplinary Core Ideas
Table of Contents
Because salt is universally needed and used, it is often fortified with important nutrients. For example, iodine is needed in the synthesis of some of the hormones produced by the thyroid gland, a butterfly-shaped gland found in the neck next to the trachea, or windpipe. Thyroid hormones play a role in regulating metabolism. Iodine is in seafood and in plants and animals that live in areas with iodine-rich soil. Plants and animals grown in areas where the soil lacks iodine will not contain enough iodine for human diets. A lack of iodine in the diet causes lowered production of thyroid hormones, which can cause symptoms like weight gain and tiredness as well as goiter, an enlarged thyroid gland (SF Fig. 2.16).
Billions of people worldwide are at risk of iodine deficiency. It is especially important that pregnant woman and infants get enough iodine or the child can have severely stunted growth and impaired brain development causing lowered intelligence. Iodine deficiency is the worldwide leading cause of preventable brain damage. To increase iodine consumption, some salts are fortified with iodine (iodized salt). This involves spraying iodine on the salt, which is simple and cost-effective. Countries with high use of iodized table salt have lower levels of iodine deficiency.
Other things that have been added to table salt include
- iron, an important component of the hemoglobin molecule, which is responsible for carrying oxygen in the bloodstream;
- folic acid, which is important for pregnant women because it helps prevent brain and spinal cord defects;
- fluorine, which helps prevent tooth decay; and
- anticaking agents.
Anticaking agents are added because table salt is composed of tiny cubes with flat surfaces, these crystals stick together in humid conditions. Salt is already predisposed to clump because it absorbs water vapor from the environment. Anticaking agents make sure table salt stays free-flowing. Grains of rice in saltshakers perform a similar function.
