Effect of glucose and sucrose on cognition in healthy humans: a systematic review and meta-analysis of interventional studies

Abstract

Context Evidence suggests that plasma glucose levels may influence cognitive performance, but this has not been systematically reviewed and quantified. Objective The aim of this review was to investigate the potential effects of glucose and sucrose, compared with placebo, on cognition in healthy humans. Data Sources The electronic databases PubMed and Web of Science were searched up to December 2019. Reference lists of selected articles were checked manually. Study Selection Randomized controlled trials or crossover trials that compared glucose or sucrose with placebo for effects on cognition were eligible. Data Extraction Potentially eligible articles were selected independently by 2 authors. Risk of bias was assessed through the Cochrane Collaboration tool. Standardized mean differences (SMDs) were obtained from random-effects meta-analyses for a subsample of studies that reported the same outcomes. Results Thirty-seven trials were identified, of which 35 investigated the effect of glucose consumption compared with placebo on cognition. Two studies found no effect of glucose on cognition, while the others found mixed results. Only 3 of the 37 studies investigated the effects of sucrose intake, reporting mixed results. Meta-analyses revealed a significantly positive effect of glucose compared with control, but only when a verbal performance test (immediate word recall) was used in parallel-design studies (SMD = 0.61; 95%CI, 0.20–1.02; I2 = 0%). Twenty-four studies were classified as having high risk of bias for the selection procedure. Conclusions A limited body of evidence shows a beneficial effect of glucose in individuals performing immediate verbal tasks. High-quality trials with standardized cognitive measurements are needed to better establish the effect of glucose or sucrose on cognition. Systematic Review Registration PROSPERO registration number CRD42019122939.

The EAT–Lancet reference diet and cognitive function across the life course

“…76 In adults, consumption of glucose has shown a beneficial effect on immediate recall tasks in verbal memory assessments. 77 A meta-analysis of interventional and observational studies showed no effects on cognitive function of consumption of sweeteners in children or adults. 78 Compared with sugar consumption, however, multiple studies showed that consumption of the artificial sweetener aspartame is associated with poor cognitive performance.…”

Association of consumption of sugar-sweetened beverages with cognitive function among the adolescents aged 12–16 years in US, NHANES III, 1988–1994

“…The dynamic utilization of glucose by the cerebral cortex over the course of development suggests that the relative apportionment of glucose must also be dynamic ( 45 ), and since the glucose cannot be stored in the brain, at the right level of sugar intake, SSBs may raise the blood sugar level in the brain and boost brain metabolism, leading to higher cognitive scores ( 46 ). The result of a systematic review and meta-analysis of interventional studies also revealed modest beneficial effects of glucose on cognition, particularly recognition memory and attention processes ( 47 ).…”

How Does Fasting Affect Cognition? An Updated Systematic Review (2013–2020)

“…Additionally, we included studies that used ingestion of a glucose beverage as a control condition since an increasing number of studies include this method as a comparison to fasting. Evidence shows that ingesting even small amounts of glucose in a fasted state can impact physiology and cognition similarly to eating [32,33]. We had no inclusion or exclusion criteria specific to water ingestion, duration of a fast, nor the number of fasts the participant completed (i.e., fasting could have been short-or long-term or conducted multiple times akin to intermittent fasting so long as a fasted and non-fasted condition were compared).…”