Scientific research is an essential public health function, enabling recognition of problems that compromise health and facilitating solutions. Research is essential to formulate health policy at a national level. There has been significant but inconsistent overall progress, due to economic conditions in low- and middle-income countries. An example that illustrates this situation is the investigation of iodine deficiency (ID) in Peru, and the application of the results for development of a public health program. The research demonstrated persistent ID, which causes fetal brain damage and subsequent mental retardation. The use of iodinated oil to prevent and treat ID was shown to have an immediate and long-term effect, and confirmed that urinary concentration of iodine was the best indicator of iodine intake. These results were accepted by the Ministry of Health, and the National Program for the Control of Endemic Goiter and Cretinism was created in 1983, achieving virtual elimination of ID by 1995.