Acute effects of fruit flesh of two Saudi date varieties differing in phenolic content and compared with a sugar- and fibre-matched placebo on mood and cognition in healthy young volunteers: a randomised, double-blind, crossover study.

PURPOSE: This paper aimed to investigate the acute effect of crisp mature fruit flesh of two varieties of Saudi dates (Barhi and Khassab), containing 184 and 424 mg Gallic Acid Equivalents (GAE) of phenolic acids per portion, respectively, on cognitive performance, mood, and blood glucose concentration. METHODS: The study employed a randomised, double-blind, placebo-controlled, crossover design with 35 healthy young participants aged 18-35 years, with a one-week washout period between visits. Computerised tests for attention and episodic memory were utilised to assess cognitive function at baseline and 45, 90 and 135 min post-consumption. Freeze-dried powder corresponding to 115 g fresh weight of pitted fruit was served in 150 g of yoghurt as the vehicle and placebo. All three treatments were matched regarding fibre and sugars. RESULTS: For the individual task outcomes, after a Bonferroni correction (α = 0.0017), the only significant difference observed was a longer Digit Vigilance reaction time after consumption of Barhi (p = 0.001), indicating slower performance compared to Khassab, while Khassab did not differ from placebo. None of the cognitive indices reached significance (α = 0.0063). Regarding mood indices with α = 0.0167, consumption of Khassab significantly increased alertness (p = 0.005) and reduced calmness (p = 0.001), with no effect of Barhi (p > 0.4 for both outcomes). No significant changes in blood glucose levels were detected. CONCLUSION: Although a cautious statistical approach was employed, Khassab and Barhi date cultivars each showed different possible effects on specific areas of cognitive function in "young and healthy" participants, justifying future studies to assess replicability. The effects were not correlated with phenolic acid dose and did not represent general enhancement or deterioration of cognitive performance.