4. Discussion
fatigue
The results of the current study suggest that the consumption of 300 mg coffeeberry extract has no effect on mood, performance of cognitively demanding tasks, or episodic memory up to 120 min post dose. Limited results were observed following 100 mg coffeeberry, which followed a pattern of negative effects. Specifically, compared to placebo, participants who received 100 mg coffeeberry reported increased mental fatigue during performance of cognitively demanding tasks at 60 min post dose, although no effect was observed for mental fatigue on the EFS-State. In addition, decreased accuracy on the RVIP task was also observed following 100 mg coffeeberry at 60 min post dose compared to placebo. In contrast to this, a consistent pattern of alerting and performance enhancing effects was observed following 75 mg caffeine compared to placebo—and in some instances also compared to the two coffeeberry beverages—confirming that the study procedures were sensitive, despite the null or negative effects observed following the coffeeberry interventions.The findings of the present study differ from those reported in previous intervention trials investigating coffeeberry extract either co-supplemented with other phenolics or administered in isolation. Specifically, the negative results following 100 mg coffeeberry extract observed here are unexpected and difficult to explain; however, when considering the current literature, there is some disparity in findings at this dosage. Previously, 100 mg of the same coffeeberry extract that was evaluated in the current study co-administered with 275 mg apple extract had no effect on performance of the CDB (also with four repetitions per assessment) or measures of episodic memory and executive function assessed at 60-, 180- and 360-min post dose [The current study did not replicate the findings of Reed et al. [One consideration with regards to the negative findings is that it could be hypothesized in a dose–response model that any effects, positive or negative, would be exaggerated following three times the dose. However, this was not observed in the current study, with no effects observed following 300 mg coffeeberry. Therefore, given the small number and transient nature of these negative effects amongst many analyses, and the fact that this is the first report of any negative effects on cognitive performance or mood measures following interventions containing coffeeberry extract [Previously, data from our research centre has shown a consistent alerting/arousing effect of 1100 mg coffeeberry extract when administered in isolation [Besides dose, a final consideration is the timing of the assessments, which only extended until 120 min post dose in the current study. Bioavailability data suggest that a number of CGA only reach peak concentration in plasma after 4 and 6 h post dose [