Baseline glucoregulatory function moderates the effect of dairy milk and fruit juice on postprandial cognition in healthy young adults

Acute Benefits of Acidified Milk Drinks with 10-g and 15-g Protein on Shifting and Updating Performances in Young Adults: A Randomized Controlled Trial

BACKGROUND

Accumulating evidence has shown that protein-rich milk drinks can rapidly improve cognitive performance. However, the optimum doses of milk protein that are needed to improve cognitive function remain to be investigated.

OBJECTIVE

This study aimed to determine whether acidified milk drinks with 10-g and 15-g milk protein have acute benefits on key cognitive functions in healthy young adults.

DESIGN

In this double-blinded randomized control trial, 66 young adults were randomly assigned to one of three groups (0-g, 10-g, and 15-g milk protein groups). Key cognitive functions (processing speed, inhibition, shifting, updating, and working memory capacity) were assessed before and 15 and 60 min after the drink intake.

RESULTS

We found that the shifting performance improved at 15 min after intake of the acidified 10-g and 15-g milk protein drinks compared to intake of the 0-g milk protein drink, and this acute effect of the acidified 15-g milk protein drink lasted for 60 min. In addition, updating performance improved at 60 min after intake of the acidified 10-g and 15-g milk protein drinks compared to intake of the 0-g milk protein drink.

CONCLUSION

Our findings suggest that the acidified 10-g and 15-g milk protein drinks have an acute benefit on shifting and updating performance in healthy young adults.

Effect of fasting on short-term visual plasticity in adult humans

Brain plasticity and function is impaired in conditions of metabolic dysregulation, such as obesity. Less is known on whether brain function is also affected by transient and physiological metabolic changes, such as the alternation between fasting and fed state. Here we asked whether these changes affect the transient shift of ocular dominance that follows short-term monocular deprivation, a form of homeostatic plasticity. We further asked whether variations in three of the main metabolic and hormonal pathways affected in obesity (glucose metabolism, leptin signalling and fatty acid metabolism) correlate with plasticity changes. We measured the effects of 2 h monocular deprivation in three conditions: post-absorptive state (fasting), after ingestion of a standardised meal and during infusion of glucagon-like peptide-1 (GLP-1), an incretin physiologically released upon meal ingestion that plays a key role in glucose metabolism. We found that short-term plasticity was less manifest in fasting than in fed state, whereas GLP-1 infusion did not elicit reliable changes compared to fasting. Although we confirmed a positive association between plasticity and supraphysiological GLP-1 levels, achieved by GLP-1 infusion, we found that none of the parameters linked to glucose metabolism could predict the plasticity reduction in the fasting versus fed state. Instead, this was selectively associated with the increase in plasma beta-hydroxybutyrate (B-OH) levels during fasting, which suggests a link between neural function and energy substrates alternative to glucose. These results reveal a previously unexplored link between homeostatic brain plasticity and the physiological changes associated with the daily fast-fed cycle.

The impact of glycaemic load on cognitive performance: A meta-analysis and guiding principles for future research

The effect of breakfast glycaemic load (GL) on cognition was systematically examined. Randomised and non-randomised controlled trials were identified using PubMed, Scopus, and Cochrane Library (up to May 2022). 15 studies involving adults (aged 20 - 80 years) were included. Studies had a low risk, or some concerns, of bias. A random-effects meta-analysis model revealed no effect of GL on cognition up to 119 min post-consumption. However, after 120 min, immediate episodic memory scores were better following a low-GL compared to a high-GL (SMD = 0.16, 95% confidence interval [CI] = -0.00 to 0.32, p = 0.05, I2 = 5%). Subgroup analyses indicated that the benefit was greater in younger adults (<35 years) and those with better GT. A qualitative synthesis of 16 studies involving children and adolescents (aged 5 - 17 years) suggested that a low-GL breakfast may also benefit episodic memory and attention after 120 min. Methodological practises were identified which could explain a failure to detect benefits in some studies. Consequently, guiding principles were developed to optimise future study design.

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

PURPOSE OF REVIEW

The goal of this review was to provide an update on the literature examining how voluntary, temporary abstention from eating impacts cognitive function.

RECENT FINDINGS

We evaluated peer-reviewed articles published between August 2013 and January 2021 that assessed adults, included a measure of cognitive functioning with neutral stimuli, and compared individuals in a fasted state to individuals in a fed state (either within- or between-subject designs). Nineteen articles (21 studies) met inclusion criteria. Sample sizes, fasting methods, and tasks varied across studies. Review of studies indicated that fasting was associated with deficits in cognitive functioning; few studies indicated a benefit in cognitive functioning following a single voluntary fast. The heterogeneity and rarity of available studies limits the conclusions that can be drawn. Several crucial psychosocial and sociodemographic moderators remain unexplored. Recommendations for future work are discussed.

Effects of a single dose of tablets containing lactononadecapeptide on cognitive function in healthy adults: a randomized, double-blind, cross-over, placebo-controlled trial

Lactononadecapeptide (LNDP; NIPPLTQTPVVVPPFLQPE) is a memory-improving peptide. The current study aimed to determine the effects of a single dose of tablets containing LNDP on cognitive function in healthy Japanese men aged 30-59 years. A randomized, double-blind, cross-over, placebo-controlled trial was conducted in participants randomly assigned to receive LNDP or placebo tablets. The Uchida-Kraepelin test was used to induce cognitive load in participants as a model of work load. Cognitive function was evaluated using the Japanese version of the CNS Vital Signs. Composite memory and verbal memory were significantly higher following consumption of LNDP than placebo tablets. Carryover effects were observed in attention and concentration domains so that period 1 data was analyzed. LNDP consumption led to higher processing speed, executive function, and cognitive flexibility than placebo. Thus, supplementation with a single dose of LNDP tablets may improve cognitive functions including memory, attention, concentration, and information processing in daily life.

Varying roles of glucoregulatory function measures in postprandial cognition following milk consumption

PURPOSE

Past work suggests milk consumption may facilitate cognition in children and college students with higher fasting glucose compared to other beverages (e.g., fruit juice). However, no studies have evaluated this phenomenon in adults, or considered other measures of glucoregulatory function. This open-label study assessed the role of glucoregulatory function in postprandial cognition after milk intake in adults. We hypothesized participants with lower fasting or post-consumption plasma glucose following a glucose excursion challenge (glucose response) would demonstrate better cognition following beverages of higher (juice) versus lower (milk) or no (water) glycemic content.

METHODS

Forty-four nondiabetic, overnight-fasted adults attended three laboratory visits, ingesting 237 mL of 2% fat milk, apple juice, or water at each visit in a randomized, counterbalanced, crossover design. Participants completed cognitive testing (CNS Vital Signs) at baseline and 30, 90, and 150 min post-ingestion; primary outcomes were CNS Vital Signs composite scores. Fasting and post-consumption plasma glucose levels were assessed, with glucose response indexed as the change in plasma glucose from baseline to 30 min after juice (ΔGlucose).

RESULTS

Mixed modeling revealed participants with higher fasting glucose demonstrated better complex attention after water versus juice at 30 min, but better performance after juice versus water at 150 min (p = 0.02). Participants with a larger ΔGlucose demonstrated better processing speed (p = 0.01) 30 min after milk versus water; this effect also reversed at 150 min.

CONCLUSION

Different methods of measuring glucoregulatory function reveal its differing roles in postprandial cognition. Time since ingestion may also determine which beverages best optimize cognition.

Relationship of a Special Acidified Milk Protein Drink with Cognitive Performance: A Randomized, Double-Blind, Placebo-Controlled, Crossover Study in Healthy Young Adults

A previous in vivo study with rats suggested that a special milk protein drink manufactured using an acidification procedure to suppress the aggregation of milk proteins was absorbed quickly after feeding. We performed a randomized, double-blind, placebo-controlled, repeated-measure crossover study to investigate the short-term effects on cognitive performance in 29 healthy young adult men after they consumed this drink in the morning. After an overnight fast, subjects were tested for performance in the Uchida⁻Kraepelin serial arithmetic test and the Stroop test as well as for subjective feeling, body temperature, and heart rate variability before and after consumption of either the acidified milk protein drink or an isoenergetic placebo drink. Subjects showed a significant improvement in performance in the Uchida⁻Kraepelin test, the primary outcome measured, when they consumed the acidified milk protein drink compared with the placebo control condition. In addition, consumption of the acidified milk protein drink, compared with the placebo control, was associated with increases in vagally-mediated heart rate variability indices which, from recent theoretical perspectives, may reflect a higher ability to modulate cognitive and behavioral processes. There was no significant difference in subjective feelings and body temperature between the test drink conditions. These data suggest that consumption of the acidified milk protein drink may improve cognitive performance, with possible involvement of physiological systems that regulate cognition and behavior.