The Effect Of Berry Polyphenols On Human Behaviour
Condition: Healthy
Study type: Interventional

Summary: 
      Polyphenols, compounds found at high levels in berry fruit, have been shown to have health
      promoting benefits through various mechanisms both in vivo and in vitro. These benefits
      include antioxidant activity, anti-inflammatory properties, and monoamine oxidase (MAO)
      inhibition. This study aims to expand on the extremely promising animal data in the
      literature, and our own pilot study results, to investigate whether drinks containing berry
      fruit can improve cognitive performance and mood in healthy human participants.

      Our central hypothesis is that fruit extracts can reduce the breakdown of neurotransmitters
      such as dopamine and serotonin. This reduction in breakdown could therefore increase the
      levels of these neurotransmitters and convey some benefits in regards to mood and cognitive
      function. The investigators will assess the pharmacokinetic activity of berry fruit extracts
      on MAO activity to test this hypothesis.

      A second hypothesis is that berryfruit polyphenols may alter circulating levels of glucose
      that may in turn affect cognitive performance and mood.

      A prior study carried out by Plant & Food Research through collaboration with the University
      of Northumbria, UK, found promising results after acutely supplementing participants with a
      berry fruit based drink. This study aims to use the results from the previous study to assess
      in depth the effect of berry fruit drinks on human behaviour.
    

Detailed description: 
      This project will investigate the acute effects on human cognitive behaviour and mood of a
      single consumption of 2 berryfruit drinks (with balanced polyphenol content) versus a
      placebo. Drinks are matched for taste, sugar content and appearance. Drinks contain natural
      berry fruit grown and juiced or extracted in New Zealand under food-safe conditions.

      The study will follow a double-blind, counterbalanced, placebo controlled, repeated measures
      design with 36 healthy participants aged between 18 and 30 completing 3 study day sessions as
      well as one training/screening visit (four visits in total). On one occasion participants
      will receive a placebo, on another berryfruit drink 1, and on another berryfruit drink 2.
      Study days will be spaced one week apart to accommodate a wash out period. Both berryfruit
      drinks will be made to include 500mg of polyphenols/60kg of body weight. Sucralose
      (artificial sweetener) will be added to make the drinks palatable. Participants will be
      screened for any intolerance or allergies to the drinks during the training/screening
      session.

      Psychometric tasks and mood scales will be measured using the Computerised Mental Performance
      Assessment System (COMPASS), a purpose designed software application for the flexible
      delivery of randomly generated parallel versions of standard and novel cognitive assessment
      tasks that has previously been shown to be sensitive to nutritional interventions and was
      used in the prior study conducted at Northumbria University. The cognitive assessment battery
      will include: Bond-Lader mood scales, visual analogue mood scales, 7 repetitions of Digital
      Vigilance, Stroop, Rapid Visual Information Processing and Mental Fatigue Visual Analogue
      scales. This is followed by a logical reasoning task and a final set of the Bond-Lader mood
      scales.

      Baseline cognitive testing will involve one repetition of the cognitive assessment battery
      (Bond-Lader mood scales, Visual Analogue scales, Digital Vigilance, Stroop and RVIP followed
      by a second set of Visual Analogue scales).

      On all 3 testing days participants will arrive at the lab in the morning (8:30 am), after an
      overnight fast, and firstly give a 10 mL venous blood sample taken by a trained phlebotomist.
      Participants will then have their blood glucose measured via a finger prick and heart
      rate/blood pressure (autonomic measures) measured using an automated digital blood pressure
      monitor. Participants will then complete one repetition of the COMPASS computerised cognitive
      assessment battery (baseline). Participants will then be orally supplemented with treatment
      in the form of a single serve juice drink.

      After a 60 minute absorption period, autonomic measurements and a second blood glucose
      reading will be taken. Participants will then complete the COMPASS assessment. After
      completion of the assessment, a third set of autonomic measurements will be immediately taken
      along with a third blood glucose reading and a second 10 mL venous blood sample.
    

Intervention name(s): Berry Polyphenols; Placebo
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): Placebo control containing sugar and artificial flavouring.
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Basic Science
Keywords: Berry phenolics; mood; cognition; adults