Universal salt iodization remains insufficient to prevent iodine deficiency without maternal education and improved household salt practices: insights from structural equation modelling in Noakhali

Despite decades of universal salt iodization (USI), iodine deficiency remains a persistent public health problem in Bangladesh, mainly impacting children in rural and socioeconomically disadvantaged communities. A cross-sectional survey of 400 children (6–12 years) in four upazilas of Noakhali measured UIC using the Sandell–Kolthoff method. A validated questionnaire was used to estimate how much mothers knew and how they used salt in their homes. We used χ 2 tests, multinomial logistic regression, and SEM to look at associations and pathways. Among households, 42 % continued to use raw or non-iodized salt, while only 58 % reported using iodized salt. Of children, 45.8 % had optimal UIC (100–299 μg/L), whereas 14.5 % and 25.3 % exhibited severe and mild iodine deficiencies, respectively. The AOR for iodized versus non-iodized salt = 14.38; 95 % CI: 6.91–29.94; p < 0.001) indicated a strong correlation with adequate UIC, along with urban residence, higher maternal education, and use of branded iodized salt. The SEM showed that maternal knowledge was a significant predictor of children's UIC (standardized β = 2.07; p = 0.004), whereas socioeconomic factors had less pronounced, indirect effects. Iodine deficiency remains common among school-aged children in Noakhali, and it is more closely linked to what their mothers know and how they use salt at home than to their income. To reduce iodine deficiency, it is important to improve community education and ensure that people can access properly iodized salt, especially in rural areas. • Maternal knowledge and household salt practices have a stronger impact than income or socioeconomic status. • Iodization alone is insufficient unless complemented by maternal education and access to packaged, branded iodized salt. • The findings also offer robust, evidence-based insight to refine iodine deficiency disorder (IDD) elimination programmes, not only in Bangladesh but in other low- and middle-income countries facing similar disparities.