Iodine supplementation should be implemented to prevent and treat iodine deficiency disorders (IDD). However, More than adequate or excessive iodine levels are unsafe and may lead to hypothyroidism and autoimmune thyroiditis.
Effects of Increased Iodine Intake on Thyroid Disorders
September 2014
Xin Sun, Zhongyan Shan, and Weiping Teng
Abstract
Iodine is a micronutrient essential for the production of thyroid hormones. Iodine deficiency is the most common cause of preventable mental impairment worldwide. Universal salt iodization (USI) has been introduced in many countries as a cost-effective and sustainable way to eliminate iodine deficiency disorders for more than 25 years. Currently, the relationship between USI and iodine excess has attracted more attention. Iodine excess can lead to hypothyroidism and autoimmune thyroiditis, especially for susceptible populations with recurring thyroid disease, the elderly, fetuses, and neonates. Nationwide USI was introduced in China in 1996. This review focused on the effects of iodine excess worldwide and particularly in China.
CONCLUSIONS
Iodine is required for the production of thyroid hormones. Although iodine supplementation should be implemented to prevent and treat IDDs, iodine intake must be maintained at a safe level. The majority of excessive iodine exposure cases does not generally result in apparent clinically fatal consequences but could be harmful. More than adequate or excessive iodine levels are unsafe and may lead to hypothyroidism and autoimmune thyroiditis, especially for susceptible populations with recurring thyroid disease, the elderly, fetuses, and neonates. TSH levels are increasing in the Chinese population and the consequences of excessive iodine should be closely investigated.
