Ethics approval and consent to participate
The study protocol was in accordance with the declaration of Helsinki and was approved by the Research Ethics Committee of the TUMS, Tehran, Iran (ethics code: 2478/130). It was recorded in the Iranian Registry of Clinical Trials Center with code IRCT201305212324N9 on 18/1/2014. The first sampling was on 20/03/2014. Informed written consent was obtained from all subjects before the start of the study and they were fully informed about the study objectives and methodology. Moreover, the participants ensured the confidentiality of their information, and they were allowed to leave the study at any time. All participants’ information was kept in a personal file which was locked with limited access. The Consolidated Standards of Reporting Trials (CONSORT) guidelines have been followed in this study.