An investigation into the acute effects of treatments created and developed from either date fruit or date seeds on the mood and cognitive performance of healthy young volunteers

Abstract

Ph. D. ThesisThe first aim of this thesis was to assess and compare the effects of an acute dose of two varieties of mature unripe freeze-dried date fruit (Barhi and Khassab) on cognitive performance, mood, and blood glucose concentration. An acute randomised, doubleblind, placebo-controlled, crossover study with a week washout period between visits was conducted on thirty-five healthy young participants (18–35 years). Cognitive function was assessed using computerised tests for attention, working and episodic memory before and 45, 90 and 135 minutes after treatment. Participants consumed the equivalent of 115 g of fresh weight fruit, which differed in the total phenolics content. The vehicle was yoghurt (150 g per portion), and the placebo was yoghurt with added sugars matching the treatments for sugars. There were no significant differences in cognitive responses for the individual task outcomes (p = 00625), nor for the cognitive indices outcomes (p = 0.0017 after Bonferroni correction). Roasted date seed drink is a popular beverage in Arab countries, so the second aim of this thesis was to assess the acute effect of a “coffee-like beverage” made from commercial date seeds on mood and cognitive function. It was postulated that some potential benefits may be related to the content of phenolic compounds in the date seeds which were characterised using HPLC. A randomised, double-blind, placebocontrolled, crossover study was conducted on fifty-two healthy young participants. Cognitive function was assessed as in the first trial, that is, before and 45 and 90 minutes after treatment. The experimental date beverage was tested against a positive control “regular coffee” and a placebo. The trial was designed to have 85% power to detect an effect size of half the published effect of regular coffee. The vehicle was hot water (280 ml per cup), with the date beverage obtained from 45 g of roasted ground date seeds, the regular coffee from 6 g of roasted ground coffee, and the placebo was hot water with brown food colour matched to the treatments. There were no significant differences in cognitive effects among the three treatments, indicating not only that the date beverage did not affect cognitive function, but that the published effect of coffee also may not be consistently reproducibl