Effects of (poly)phenol-rich cranberry on mental health in university students: The CRANMOOD randomised controlled trial

BACKGROUND AND AIMS: Increasing evidence indicate that (poly)phenol-rich foods can have beneficial effects on human brain function. This study investigated whether daily (poly)phenol-rich cranberry supplementation for 12 weeks influences mental health outcomes in university students. METHODS: A parallel double-blind randomised controlled trial was conducted in 72 young healthy final year university students (20-25 years old). Participants consumed either a (poly)phenol-rich cranberry drink or a placebo drink daily for 12 weeks. The primary outcome was mood, assessed as Total Mood Disturbance (TMD), using the Profile of Mood States questionnaire. Secondary outcomes included stress, anxiety and depression levels, measured using the Perceived Stress Scale (PSS) and the Hospital Anxiety Depression Scale (HADS) questionnaires, cognitive function, measured using the Online General Cognitive Assessment Battery (CogniFit), and salivary cortisol levels. Blood and urine samples were collected to measure cranberry (poly)phenol metabolites. Dietary intake was assessed via food frequency questionnaires (FFQ), 7-day food diaries (EPIC, European Prospective Investigation into Cancer and Nutrition), and 24-h online dietary recalls (intake 24). Data was analysed using linear mixed-effects models using baseline as covariate. RESULTS: No significant differences were observed between groups for the primary outcome, self-reported mood (Total Mood Disturbance), or for secondary self-reported measures of stress, anxiety, or depression. In exploratory secondary analyses, 12 weeks of (poly)phenol-rich cranberry drink consumption significantly reduced diurnal area under the curve of salivary cortisol (p = 0.010) and significantly improved both short-term memory (p = 0.024) and phonological short-term memory (p = 0.014) compared to placebo. Additionally, plasma and urinary cranberry (poly)phenol metabolites were significantly modulated by cranberry consumption. CONCLUSIONS: While (poly)phenol-rich cranberry supplementation did not improve self-reported mood, stress, anxiety, or depression in healthy students, it influenced cortisol levels and some aspects of cognitive function, suggesting potential benefits for stress regulation and memory. CLINICAL TRIAL REGISTRY: The National Institutes of Health (NIH)-randomized trial records held on the NIH ClinicalTrials.gov website (NCT05260346).