Table 1.

Population–intervention–comparison–outcome (PICOS) criteria for study inclusion and exclusion⁽⁴³⁾

Criteria category	Inclusion	Exclusion
Population	Adults (aged ≥ 18 years)	Individuals (aged < 18 years), unless results display separate data; adults residing in developing countries; populations with a high prevalence of thyroid disorders
Intervention/exposure	Participants with any type of dietary preference or restriction. Voluntary or otherwise	Use of a dietary grouping without defining diet characteristics
Comparators	Differing dietary preference or restriction	None
Outcome measure	Iodine intake or status measured by urinary iodine concentration (UIC) or analysis of dietary records	No analysis of iodine intake or status; use of thyroid measures alone for iodine intake and status
Study design	Any study design with relevant outcomes	None