The Effect Of Berry Polyphenols On Human Behaviour

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.

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.

Eligibility Criteria:
Inclusion Criteria:

* MMale/female,
* Healthy Age 18-35 years old
* Non smoker
* Proficient in English
* Not taking any herbal or prescription medications
* Not pregnant or seeking to become pregnant, BMI \< 30kg/m2

Exclusion Criteria:

* Tobacco user,
* pregnant or seeking to become pregnant,
* currently taking recreational over the counter/prescription medication (excluding the contraceptive pill) and/or dietary/herbal supplements.
* Food allergies or sensitivities that are relevant to the study,
* learning difficulties,
* ADHD,
* dyslexia,
* migraines or
* any gastric problems