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Review
, 10 (2)

The Effects of Carbohydrates, in Isolation and Combined With Caffeine, on Cognitive Performance and Mood-Current Evidence and Future Directions

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Review

The Effects of Carbohydrates, in Isolation and Combined With Caffeine, on Cognitive Performance and Mood-Current Evidence and Future Directions

Boyle Neil Bernard et al. Nutrients.

Abstract

This review examines the effects of carbohydrates, delivered individually and in combination with caffeine, on a range of cognitive domains and subjective mood. There is evidence for beneficial effects of glucose at a dose of 25 g on episodic memory, but exploration of dose effects has not been systematic and the effects on other cognitive domains is not known. Factors contributing to the differential sensitivity to glucose facilitation include age, task difficulty/demand, task domain, and glucoregulatory control. There is modest evidence to suggest modulating glycemic response may impact cognitive function. The evidence presented in this review identifies dose ranges of glucose and caffeine which improve cognition, but fails to find convincing consistent synergistic effects of combining caffeine and glucose. Whilst combining glucose and caffeine has been shown to facilitate cognitive performance and mood compared to placebo or glucose alone, the relative contribution of caffeine and glucose to the observed effects is difficult to ascertain, due to the paucity of studies that have appropriately compared the effects of these ingredients combined and in isolation. This review identifies a number of methodological challenges which need to be considered in the design of future hypothesis driven research in this area.

Keywords: caffeine; carbohydrate; cognitive performance; glucose; glycemic response; subjective mood.

Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Scatterplot of cognitive performance outcomes (enhanced or impaired) by caffeine and CHO drink content. Data are representative of all studies reviewed and include multiple outcomes reported by single studies. Howard and Marczinski [176] not shown due to caffeine/CHO being administered based on body weight. Aniţei et al. [174] not shown as do not state CHO dose.
Figure 2
Figure 2
Scatterplot of subjective outcomes (enhanced or impaired) by caffeine and CHO drink content. Data are representative of all studies reviewed and include multiple outcomes reported by single studies. Howard and Marczinski [176] not shown due to caffeine/CHO being administered based on body weight. Aniţei et al. [174] not shown as do not state CHO dose.

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