Iodine Intake and Risk of Mortality: Evidence from a Nationally Representative Korean Cohort

Area of Science:

• Nutrition Science
• Epidemiology
• Public Health

Background:

• Iodine intake is crucial for thyroid and metabolic health, impacting public health.
• Limited longitudinal data exists on iodine intake and mortality, especially in non-Western populations.
• Asian populations exhibit high iodine intake, necessitating studies on ethnic/regional variations in iodine sensitivity.

Purpose of the Study:

• To investigate the association between iodine intake and all-cause, cardiovascular, and cancer mortality in an Asian population.
• To address the scarcity of longitudinal data on iodine intake and mortality outside Western countries.
• To explore potential ethnic or regional differences in iodine sensitivity and its health outcomes.

Main Methods:

• Analysis of 5497 Korean adults from the Korean National Health and Nutrition Examination Survey (2013-2015) with mortality follow-up.
• Quantification of urinary iodine concentration (UIC) using inductively coupled plasma mass spectrometry.
• Estimation of iodine intake from UIC, categorized relative to requirements and upper limits, analyzed using Cox proportional hazards models.

Main Results:

• Over 8.4 years, excessive iodine intake (above tolerable upper level) showed no association with all-cause, cardiovascular, or cancer mortality.
• No significant mortality trends were observed across different iodine intake categories.
• Sensitivity and subgroup analyses, including those excluding participants with thyroid disease, did not alter the primary findings.

Conclusions:

• This is the first population-based Asian study linking iodine intake to mortality, finding no association.
• Results suggest the iodine-mortality relationship may vary significantly across different global populations.
• Further large-scale international studies are essential to elucidate the complex interplay between iodine exposure and mortality.