Although your body needs only small amounts of iodine, its role in your body is anything but small. Iodine is critical for the production of your thyroid hormone, which has many important roles. The thyroid hormone is essential in adults and during fetal life and childhood, when it supports the normal development of the brain and other organs 9. Iodine may have other key roles in the body, although these are not yet fully understood.
Iodine and Your Thyroid
According to the Institute of Medicine, iodine makes up about 59 percent of T3 and 65 percent of T4 by weight. These hormones have extensive roles throughout your body, and iodine is essential to produce them. Thyroid hormones act on every type of cell in your body, raising the overall level of cellular activity -- called the metabolic rate. In most cells, it does this by increasing the number of energy-producing components, or mitochondria. Ultimately, your thyroid hormone has many wide-ranging effects, including keeping your body temperature at a normal level, helping regulate blood glucose and helping mobilize stored fats and other nutrients when you need extra energy.
Iodine and Fetal Development
Getting enough dietary iodine is crucial during all phases of human development, including before birth. A woman's adequate intake of iodine during pregnancy helps ensure normal production of thyroid hormones, which are required for early formation and growth of fetal organs. Without enough thyroid hormone, the risk of miscarriage, stillbirth and birth defects increases. Insufficient iodine during pregnancy can also cause an infant's weight to be abnormally low at birth.
Adequate iodine intake and normal thyroid hormone levels are especially important for fetal brain development. Without enough iodine, nerve cells in the fetal brain could grow at a reduced rate and slow production of a myelin -- a substance essential for conduction of nerve impulses. A study in the July 2013 issue of "Lancet" evaluated iodine levels in about 1,000 pregnant women and tested their children at ages 8 and 9 for verbal intelligence and reading ability 7. Children whose mothers had the lowest iodine levels during pregnancy were most likely to score poorly on the tests.
Iodine After Birth
An infant or child also needs to consume enough iodine for continued growth of his brain and nerves. A 2010 review in "Indian Journal of Endocrinology and Metabolism" reported that iodine deficiency during childhood can cause poor learning, slow mental development or speech or hearing problems 4. In adults, iodine remains important for normal brain function. Iodine deficiency and low thyroid hormone, or hypothyroidism, often causes slow mental function, sensitivity to cold, muscle weakness or intestinal problems.cause:
- Iodine deficiency
- low thyroid hormone
- or hypothyroidism
- often causes slow mental function
- sensitivity to cold
- muscle weakness or intestinal problems
Iodine in Other Organs
The salivary glands, stomach lining, parts of the eyes and other organs also take up iodine. For example, a report published in the April 2005 issue of "Journal of Mammary Gland Biology and Neoplasia" reported that diets high in iodine are associated with low breast cancer rates 6. The authors suggest that iodine might prevent abnormal growth and division of breast cells, but further research is still needed to confirm this.
An infant or child also needs to consume enough iodine for continued growth of his brain and nerves. Adequate iodine intake and normal thyroid hormone levels are especially important for fetal brain development. A woman's adequate intake of iodine during pregnancy helps ensure normal production of thyroid hormones, which are required for early formation and growth of fetal organs.
- National Institutes of Health, Office of Dietary Supplements: Iodine
- Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium and Zinc: Iodine
- Endocrinology: An Integrated Approach: The Thyroid Gland
- Indian Journal of Endocrinology and Metabolism: Iodine, Iodine Metabolism and Iodine Deficiency Disorders Revisited
- Thyroid: The Extrathyronine Actions of Iodine as Antioxidant, Apoptotic, and Diifferentiation Factor in Various Tissues
- Journal of Mammary Gland Biology and Neoplasia: Is Iodine a Gatekeeper of the Integrity of the Mammary Gland?
- Lancet: Effect of Inadequate Iodine Status in UK Pregnant Women on Cognitive Outcomes in Their Children: Results From the Avon Longitudinal Study of Parents and Children (ALSPAC)
- Seminars in Cell and Developmental Biology: The Role of Iodine in Human Growth and Development
- Current Clinical Pharamacology: The Implications of Iodine and Its Supplementation During Pregnancy in Fetal Brain Development
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