Clinical Research Directory

Inclusion Criteria: * Male or female, aged 21 to 60 years. * Meets the operational diagnostic criteria for subthreshold depression. * Has not been following a Mediterranean-style diet, based on self-report and a - Mediterranean Diet Adherence Screener (MEDAS) score ≤9. * Able to converse in English. * Able to use a computer or mobile device with internet access. * Capable of providing informed consent. Exclusion Criteria: * Current use of antidepressants, antipsychotics, or mood stabilizers. * Self-reported lifetime diagnosis of bipolar disorder, a psychotic disorder, an eating disorder, or a current substance use disorder. * Major life trauma, such as recent bereavement or job loss, within the preceding 3 months. * Current participation in an intervention targeting diet. * Severe food allergies, intolerances, or aversions. * Unwilling to accept a Mediterranean-style diet. * Current daily or regular use of over-the-counter or prescription probiotic/prebiotic supplements. * Systemic oral or intravenous antibiotic use within 30 days before the study. * Self-reported chronic gastrointestinal disorder, including inflammatory bowel disease, irritable bowel syndrome, or celiac disease. * Self-reported history of significant gastrointestinal surgery, such as gastric bypass or bowel resection. * Self-reported systemic autoimmune disease or active chronic infectious disease. * Currently pregnant or lactating, or planning pregnancy during the study.