Prevalence and Determinants of Iodized Salt Purchase: Findings from an In-Person Supermarket Survey in Northern Portugal

Background/Objectives: Iodine is an essential micronutrient required for the synthesis of thyroid hormones, fundamental in metabolic processes throughout life. Salt iodization is recognized as the most cost-effective and recommended strategy for the prevention of iodine deficiency disorders. In Portugal, the use of iodized salt remains voluntary for the general population, dependent on consumers’ choice, where iodized salt accounts for approximately 11% of retail salt sales. This cross-sectional study aimed to evaluate prevalence, knowledge, and motives of iodized salt purchase among consumers in all stores of a major supermarket chain in Braga, Portugal. Methods: A questionnaire assessing purchasing behavior, knowledge, motivations, and barriers related to choosing iodized salt was administered to individuals in supermarkets after they had selected a package of salt from the shelf, during January and February of 2023. Results: While 21% of the 396 in-store respondents reported consuming iodized salt at home, only 10% were observed purchasing it in the store. Approximately half were unaware of the availability of iodized salt, and only 20% associated health benefits with it. Perceived health benefits were the most frequently reported motives for purchase, whereas lack of knowledge emerged as the main barrier. Conclusions: These findings indicate a low prevalence of iodized salt use and limited awareness of its availability and its role in preventing iodine deficiency disorders among this large urban population, consistent with reports of low iodized salt sales nationwide. Stronger public health measures, including literacy campaigns, improved product labeling and visibility, and broader policy actions such as universal salt iodization should be considered.