Iodine intake in adults: Sociodemographic and dietary determinants from a National Health survey

Iodine is an essential micronutrient for thyroid hormone synthesis and neurological function. Despite long-standing salt iodization programs, both iodine deficiency and excess remain public health concerns. This study aimed to estimate daily iodine intake and identify sociodemographic and dietary factors associated with iodine intake among Chilean adults.

A cross-sectional analytical study was conducted using data from the 2016-2017 Chilean National Health Survey. Iodine intake (μg/day) was estimated from urinary iodine concentration adjusted for body weight. Linear regression models, accounting for complex survey design, were used to examine associations with sociodemographic, anthropometric, and dietary variables.

Data from 1230 adults aged ≥18 years were analyzed. Mean iodine intake was adequate overall but higher in men than women (425 vs. 322 μg/day, p < 0.001). Iodine intake decreased significantly with age and was positively associated with waist circumference. Frequent dairy consumption was a key dietary determinant: those with frequent or moderate intake showed higher iodine intake than those with very frequent consumption (p = 0.006).

Although the average iodine intake among Chilean adults was adequate, women and older adults showed lower intake levels. Maintaining salt iodization policies and promoting iodine-rich foods, particularly dairy and fish, are essential to prevent reemerging deficiencies in vulnerable groups.