2.2. Participant Interview and Sample Collection Procedures
weight loss
GROUP B
Initially, volunteers completed an online pre-registration form with a study description. Each volunteer was contacted by phone to explain the objectives and criteria for participating in the study. After the eligibility analysis, the volunteers were randomly allocated, according to the order of registration, to Group A (odd numbers) or Group B (even numbers). The survey was carried out during the COVID-19 pandemic; thus, social distancing was necessary during data collection. For this reason, a kit was delivered to the participant’s residence containing the following: the informed consent form, a salivary collection kit with a guideline for use, 3-day food log, self-reported inventories (BECK scale, BDI-II), a blank sheet, and a bottle containing 30 placebo or Zn capsules for the first 30 days of the study.After the kit delivery, an online meeting was conducted for anamnesis, application of cognitive tests, and to give instructions about the acquisition of anthropometric measurements, completion of the inventories, and saliva collection.At the end of the first month of the study, delivery of placebo or Zn additional capsules was scheduled (2 bottles, 1 containing 30 capsules and the other containing 32 capsules). After 12 weeks of intervention, all tests were repeated (final evaluation). During the intervention, participants were instructed to maintain a constant diet, physical activity, and medication. No weight loss or specific diets were provided during the intervention period. At the end of the study, all participants received individualized nutritional guidance.Data were collected before and after 12 weeks of intervention. At the end of the intervention, a final visit was scheduled to obtain post-intervention saliva samples and the material with the assessments self-completed by the participants.