Modulation of the Gut-brain Axis by Cranberries: Impact on University Students' Mental Wellbeing
Condition: Healthy
Study type: Interventional

Summary: 
      In this work, the investigators will assess whether cranberry (poly)phenols improve mood
      disorders including stress, anxiety and depression via the gut-brain axis in university
      students. The investigators will evaluate whether the effects observed are related to an
      improvement in gut microbiome diversity and function, and whether the mechanism of action may
      be mediated by a decrease in inflammatory markers, modulation of neurotransmitters or via an
      alteration of BDNF levels. The investigators will also quantify the most comprehensive panel
      of cranberry (poly)phenol metabolites. A double-blind, randomized placebo controlled 2-arm
      parallel study will be conducted in the Metabolic Research Unit (MRU, Department of
      Nutritional Sciences at KCL).
    

Detailed description: 
      The study population will be final year BSc and MSc university students between 20-25 years
      old (n=60), who are generally healthy and not taking any medication. The study will be
      conducted during the period prior to their final exams (January until September). The
      intervention will be cranberry and placebo juice, consumed daily for 12 weeks, and will be
      provided free of cost by the Cranberry Institute. After a screening visit to evaluate
      inclusion and exclusion criteria, informed consent will be obtained, and subjects will be
      randomized to the treatments.

      The study will consist in a total of 4 visits, one visit every 4 weeks over a total of 12
      weeks intervention. Volunteers will consume a cranberry or a control drink every day for 12
      weeks. The day before each visit (pre-visit), volunteers will self-collect a total of 6
      saliva samples throughout the day to measure cortisol levels as a biomarker of stress. Mental
      health, cognitive function, diet and physical activity will also be assessed using
      self-reported questionnaires, an online cognitive battery test and an online 24 h dietary
      recall. In addition, on the day before visits 1 and 4 (baseline and 12 weeks), a stool sample
      will be self-collected to assess changes in gut microbiome diversity and composition. On the
      day of each visit, a spot urine sample will be self-collected after waking up and before
      breakfast. During each visit, volunteers will drop the self-collected samples, and will
      collect new kits for the next visit. Visits 1 and 4 will last approximately 20 min, while
      visits 2 and 3 will last approximately 5 minutes. In addition, during visits 1 and 4, blood
      samples will be taken to investigate changes in gut-brain axis and cranberry related
      metabolites. Blood samples will also be collected at baseline to assess general health status
      of participants (blood lipids, markers of liver and kidney function, urea, uric acid,
      creatinine, and glucose).
    

Intervention name(s): Cranberry juice; Placebo
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): composition: Water, cranberry juice concentrate; composition: Water, dextrose, citric acid, malic acid, fumaric acid, colorants, xanthan gum, natural flavor, emulsion
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Parallel assignment
Masking: Double (Participant, Investigator)
Primary purpose: Basic Science