Ethics approval and consent to participate
The ethical committee of the National Nutrition and Food Technology Research Institute (NNFTRI) of Shahid Beheshti University of Medical Sciences (SBMU), Tehran, Iran (IR.SBMU.NNFTRI.REC.1397.012), approved the study protocol. All procedures in the study involving human participants were under the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. Informed written or online consent was requested and obtained for conducting interviews with key informants, and their personal information was stored securely in a locked cabinet. As the students were not involved in the study, informed consent was not obtained from them or their parents.