Iodine nutrition optimization: are there risks for thyroid autoimmunity?

Area of Science:

• Endocrinology
• Public Health Nutrition
• Immunology

Background:

• Iodine deficiency remains a primary cause of preventable thyroid disorders globally.
• Salt iodization programs have successfully improved iodine sufficiency in many regions.
• Concerns exist regarding iodine prophylaxis potentially worsening thyroid autoimmunity.

Purpose of the Study:

• To evaluate the long-term effects of iodine supplementation on thyroid autoimmunity.
• To assess the clinical relevance of post-iodization changes in thyroid antibody positivity.
• To determine the safety and benefits of recommended iodine intake regarding thyroid autoimmunity.

Main Methods:

• Long-term observational studies on iodine supplementation.
• Analysis of thyroid antibody prevalence and positivity.
• Assessment of overt thyroid dysfunction rates over two decades.
• Evaluation of median iodine concentration in the population.

Main Results:

• An early increase in thyroid antibody positivity after iodization is transient and not clinically significant.
• Prevalence of overt thyroid dysfunction remained low over twenty years.
• Recommended iodine intake is safe, with benefits outweighing risks at iodine levels below 300 μg/L.

Conclusions:

• Iodine supplementation is safe concerning thyroid autoimmunity.
• Transient increases in thyroid antibodies do not limit the promotion of iodine supplementation.
• The benefits of iodine supplementation for thyroid health significantly outweigh potential risks.