Low-iodine diet: what to eat and avoid before iodine-131 procedures?

Objective: The aim of this study was to compile a list of low-iodine foods for use in the Low-Iodine Diet (LID) to optimize the uptake of Iodine-131 by cells, which is used in the diagnosis and treatment of thyroid gland disorders.

Methods: A bibliographic research was conducted focusing on the most commonly consumed foods in Brazil. Iodine quantification was derived from both national and international food composition tables, with an emphasis on sources indicating the highest concentrations of this microelement. The foods were organized into categories, and their iodine levels were presented in micrograms per 100 grams of food.

Results: The compiled list includes foods classified into categories such as cereals, legumes, vegetables, fruits, flours, oils, fats, meats, dairy products, and beverages. Foods with more than 50 μg of iodine per 100 g were identified and classified separately. Based on the findings, marine-derived foods should be avoided, while dairy products and eggs can be consumed, provided substitutions are made.

Conclusion: Identifying and quantifying low-iodine foods is essential for guiding the LID, making it more effective and better suited to the population's needs. Legumes, vegetables, and most fruits can be consumed in larger quantities, forming the core of the diet.