The thyroid gland is a small organ in the front of the neck that regulates various physiological processes, such as energy metabolism, protein production and human development by releasing two hormones known as T3 and T4. All cells are likely targets for these hormones. A deficiency in the synthesis of thyroid hormones is known as hypothyroidism. It results in feelings of fatigue, depression and muscle pain. Iodine is a common treatment for hypothyroidism.
Iodine
The thyroid gland requires iodine to produce T3 and T4. Iodine is a chemical element and an essential nutrient. Your body cannot manufacture iodine on its own. Instead, you must obtain iodine exclusively from your diet. Iodine is naturally present in soil and seawater. All iodine consumption derives from there, which is why it's so prevalent in seafood and certain plants, such as grains and soy. Mammalian milk, too, tends to contain iodine.
Seaweed
Seaweed is a loose, colloquial term for a group of organisms made out of complex, macroscopic algae. It's a common food in coastal cultures, such as Japan, China, Korea, Indonesia, Vietnam, Philippines, Scandinavia and parts of England. One method is to make it into noodles and mix it with local cuisines. Most types of seaweed, such as kelp, dulce and nori, are rich in iodine. This is because iodine salts are water-soluble and tend to exist in slightly higher concentrations within seawater. If the cause of your hypothyroidism is iodine deficiency, seaweed can help treat it. However, an iodine deficiency is much more common in the developing world compared to the developed world.
Iodine Content
A study published in the October 2004 issue of the journal "Thyroid" found that the iodine content of seaweed ranged from only 16 mcg in nori to approximately 8,165 mcg in a sample of processed kelp granules. By comparison, the Institute of Medicine has set a recommended dietary allowance for iodine in adult men and women at 150 mcg a day; for pregnant women it's 220 mcg, and for breast-feeding women it's 290 mcg per day.
Warning
Excessive iodine can be harmful to the thyroid gland by causing hyperthyroidism or autoimmune thyroid disease. The tolerable upper limit is 1,100 mcg per day. Kelp, dulce and certain types of Asian seaweed may exceed this limit several times over. In 2010, the Australian Medical Association warned consumers about seaweed products that contain dangerously high levels of iodine. The iodine content is rarely listed on the packaging, however, so caution is warranted if you decide to consume seaweed.
References
- Colorado State University; Mechanism of Action and Physiological Effects of Thyroid Hormones; R. Bowen; July 2010
- American Thyroid Association: Iodine Deficiency
- "Thyroid: Official Journal of the American Thyroid Association"; Variability of Iodine Content in Common Commercially Available Edible Seaweeds; J. Teas, et al.; October 2004
- ABC News; Doctors Warn on Seaweed's Iodine Danger; October 2010
