β-lactolin increases cerebral blood flow in dorsolateral prefrontal cortex in healthy adults: a randomized controlled trial

Long-term effects of an egg-protein hydrolysate on cognitive performance and brain vascular function: a double-blind randomized controlled trial in adults with elevated subjective cognitive failures

PURPOSE

Short-term intake of the egg-protein hydrolysate Newtricious (NWT)-03 improved executive function, but underlying mechanisms and long-term effects, including other cognitive domains, are unknown.

METHODS

A 36-week randomized controlled trial involving 44 overweight/obese individuals experiencing elevated Subjective Cognitive Failures (SCF; aged 60-75 years) assessed the impact of daily consumption of 5.7 g of NWT-03 or placebo powders on cognitive performance (psychomotor speed, executive function, memory) and Cerebral Blood Flow (CBF), a marker of brain vascular function. Cognitive performance was evaluated using a neurophysiological test battery (CANTAB) and CBF was measured using magnetic resonance imaging perfusion method Arterial Spin Labeling (ASL). Serum samples were collected to determine brain-derived neurotrophic factor (BDNF) concentrations.

RESULTS

Anthropometrics, and energy and nutrient intakes remained stable throughout the trial. NWT-03 was well tolerated, and compliance was excellent (median: 99%; range: 87-103%). No overall intervention effects were observed on cognitive performance or CBF, but post-hoc analyses revealed significant improvements on executive function in women, but not men. Specifically, a reduction of 74 ms in reaction latency on the multitasking task (95% CI: -134 to -15; p = 0.02), a reduction of 9 between errors (95%CI: -14 to -3; p < 0.001), and a reduction of 9 total errors (95%CI: -15 to -3; p < 0.001) on the spatial working memory task were found in women. No intervention effects were observed on serum BDNF concentrations (p = 0.31).

CONCLUSION

Long-term consumption of NWT-03 improved multitasking abilities and working memory in women with elevated SCF. Brain vascular function remained unaffected. Sex differences in executive function require additional clarification.

The effects of palatinose on attention and cerebral blood flow in healthy adults: A randomized double-blind placebo-controlled crossover study

OBJECTIVE

The primary energy source for the brain is glucose, and a continuous supply is required for the brain to work longer. This study aimed to verify the effects of palatinose on attention and cerebral blood flow in healthy adults.

METHODS

This randomized, double-blind, placebo-controlled crossover study included 64 healthy Japanese adults. Participants performed the Digit Vigilance Task (DVT) 60 min pre-ingestion (14:00) and 0 (15:00), 60 (16:00), 120 (17:00), and 180 (18:00) min after ingestion of 10 g of either palatinose or glucose. Cerebral blood flow was measured using a wearable 2CH functional near-infrared spectrometer (fNIRS) during each DVT. The participants underwent the Uchida-Kraepelin (UK) test between each DVT to control for fatigue.

RESULTS

DVT reaction times with palatinose intake were significantly shorter than those with glucose intake at 16:00, 17:00, and 18:00 (p = 0.0015, p < 0.001, and p < 0.001, respectively). The change in cerebral blood flow as a function of total hemoglobin level was significantly higher in the palatinose group than in the glucose group (p = 0.018). Regarding the post-UK mood questionnaire, "physically fatigued" and "annoyed" were significantly lower in the palatinose intake group compared to the glucose intake group at 17:00 (p = 0.0445 and p = 0.0318, respectively). Furthermore, "physically fatigued" was significantly lower, and "seriously" was higher in the palatinose intake compared to the glucose intake group at 18:00 (p = 0.00652 and p < 0.001, respectively).

CONCLUSION

These findings suggest that 10 g of palatinose has favorable effects on attention and cerebral blood flow.

TRIAL REGISTRATION

UMIN000046182.

Association Between Dairy Intake and Executive Function in Chinese Children Aged 6–12 Years

Association between dairy intake and executive function remains controversial, especially among children, a population with fast-developing executive functions. This study aimed to explore this topic. Additionally, we further distinguished the role of dairy intake types (full- or low-fat milk or yogurt) in this relationship. This survey included 5,138 children aged 6–12 years. Dairy intakes were assessed by validated questionnaires. Executive function was measured by the behavior rating inventory of executive function (BRIEF; Parent Version), and lower T-scores of BRIEF indices indicated superior executive function performance. Results showed that children with higher dairy intake had statistically better performance in Shift (46.58 ± 7.48 vs. 45.85 ± 7.10), Initiate (48.02 ± 8.58 vs. 47.14 ± 8.33), and Working Memory (50.69 ± 8.82 vs. 49.89 ± 8.73). In the analysis of multivariate linear regression, we found that for every one unit increase in full-fat dairy intake, T-scores for Shift (β = −0.350 (95% confidence interval [CI]: (−0.660, −0.039) and Initiate (β = −0.486 (95% CI: (−0.845, −0.127) were decreased and for every one unit increase in low-fat dairy intake, T-score for Organizations of Materials (β = −0.940 (95% CI: (−1.690, −0.189) was decreased. After distinguishing dairy into milk and yogurt, we observed that only milk intake, not yogurt, was significantly associated with better executive function performance in Shift (β = −0.390 (95% CI (−0.745, −0.035) and Initiate (β = −0.509 (95% CI (−0.917, −0.101) after adjusting for potential confounding factors. This study shows that a higher intake of dairy, irrespective of fat content, is related to better executive function performance among children aged 6–12. In addition, a significantly positive relationship between dairy intake and executive function’s indices of Shift and Initiate only was observed in milk, not in yogurt.

Tryptophan-tyrosine dipeptide improves tau-related symptoms in tauopathy mice

Neurodegenerative diseases involving pathological tau protein aggregation are collectively known as tauopathies and include Alzheimer's disease and Pick's disease. Recent studies show that the intake of tryptophan-tyrosine (Trp-Tyr)-related β-lactopeptides, including β-lactolin, attenuates cognitive decline in the elderly and prevents the amyloid pathology in mouse models of Alzheimer's disease. However, the effects of Trp-Tyr-related β-lactopeptides on tau-related pathology have not been investigated. In the present study, we examined the effects of Trp-Tyr dipeptide intake on tauopathy in PS19 transgenic mice, a well-established tauopathy model. Intake of Trp-Tyr dipeptide improved the behavioral deficits observed in the open field test, prevented tau phosphorylation, and increased the dopamine turnover and synaptophysin expression in the frontal cortex. Levels of short-chain fatty acids in the cecum were lower in PS19 mice than those in wild-type mice and were increased by treatment with Trp-Tyr dipeptide. In addition, intake of Trp-Tyr dipeptide extended the lifespan of PS19 mice. These findings suggest that the intake of Trp-Tyr-related peptides improves tauopathy symptoms, resulting in improvements in behavioral deficits and longevity. Hence, the intake of Trp-Tyr-related peptides, including β-lactolin, may be beneficial for preventing dementia.

β-Lactolin improves mitochondrial function in Aβ-treated mouse hippocampal neuronal cell line and a human iPSC-derived neuronal cell model of Alzheimer's disease

Mitochondrial dysfunctions are a key hallmark of Alzheimer's disease (AD). β-Lactolin, a whey-derived glycine-threonine-tryptophan-tyrosine tetrapeptide, has been previously reported to prevent AD-like pathologies in an AD mouse model via regulation of microglial functions. However, the direct effect of β-lactolin on neuronal cells and neuronal mitochondrial functions remains unknown. Here, we investigated the effects of β-lactolin on mitochondrial functions in amyloid β (Aβ)-treated mouse hippocampal neuronal HT22 cells and human induced-pluripotent cell (hiPSC)-derived AD model neurons. Adding β-lactolin to Aβ-treated HT22 cells increased both the oxygen consumption rate and cellular ATP concentrations, suggesting that β-lactolin improves mitochondrial respiration and energy production. Using high content image analysis, we found that β-lactolin improved mitochondrial fragmentation, membrane potential, and oxidative stress in Aβ-treated cells, eventually preventing neuronal cell death. From a mechanistic perspective, we found that β-lactolin increased gene expression of mitofusin-2, which contributes to mitochondrial fusion events. Finally, we showed that β-lactolin improves both mitochondrial morphologies and membrane potentials in hiPSC-derived AD model neurons. Taken together, β-lactolin improved mitochondrial functions AD-related neuronal cell models and prevented neuronal cell death. The dual function of β-lactolin on both neuron and microglia marks an advantage in maintaining neuronal health.

Effect of Whey-Derived Lactopeptide β-Lactolin on Memory in Healthy Adults: An Integrated Analysis of Data from Randomized Controlled Trials

CONTEXT

Epidemiological studies have shown that consumption of dairy products reduces the risk of dementia and cognitive decline in older individuals. Tryptophan-tyrosine-related β-lactopeptides and their representative β-lactolin of glycine-threonine-tryptophan-tyrosine tetra-peptide have been identified as agents in dairy products, which improve cognitive function as well as memory function via the activation of the dopaminergic system in a mouse model of amnesia. Previous clinical trials have shown that supplementation with β-lactolin improves memory retrieval in healthy older adults. Specifically, β-lactolin improved the scores in some neuropsychological tests. However, the effects of β-lactolin on memory function have not been clarified.

OBJECTIVES

The aim of this study was to evaluate the effect of β-lactolin on memory function using statistical methods.

DATA SOURCES

We searched the Web of Science, Cochrane Library, and JDream III until November 2021 to identify relevant randomized controlled trials for integrated analysis.

DATA SYNTHESIS

Three randomized controlled trials evaluating the effect of β-lactolin on memory in healthy adults were selected for the integrated analysis. The results showed that the score of cued recall among the neuropsychological tests in the β-lactolin group was significantly higher than that in the placebo group (g=0.33; 95% CI: 0.10, 0.55). In addition, the total memory score was higher but this difference was not significant (g=0.17; 95% CI: -0.09, 0.43).

CONCLUSIONS

Taken together, these results suggest that supplementation with β-lactolin improves cued recall in healthy older adults.

β-Lactolin Reduces Age-Related Inflammation and Cognitive Decline

With the rapid increase in aging populations worldwide, there has been an increase in demand for preventive and therapeutic measures for age-related cognitive decline and dementia. Epidemiological studies show that consumption of dairy products reduces the risk for cognitive decline and dementia in the elderly. We have previously demonstrated in randomized trials that the consumption of β-lactolin, a whey-derived Gly-Thr-Trp-Tyr lactotetrapeptide, improves cognitive function in older adults. Orally administered β-lactolin is delivered to the brain and inhibits monoamine oxidase, resulting in alleviation of memory impairment. However, there is currently no evidence of the effects of long-term β-lactolin intake on aging. Here, we found that the discrimination index in the novel object recognition test for object recognition memory was reduced in mice aged 20 months compared with that in young mice, indicating that age-related cognitive decline was induced in the aged mice; in aged mice fed β-lactolin for 3 months, memory impairment was subsequently alleviated. In aged mice, impairment of light/dark activity cycles was found to be induced, which was subsequently alleviated by β-lactolin consumption. Additionally, the number of activated microglia in the hippocampus and cortex and the production of cytokines (tumor necrosis factor-α, macrophage inflammatory protein-1α, and macrophage chemoattractant protein-1) were increased in aged mice compared with those in young mice but were reduced in aged mice fed β-lactolin. The age-related hippocampal atrophy was improved in aged mice fed β-lactolin. Cytochrome c levels in the hippocampus and cortex were increased in aged mice compared with those in young mice but were also reduced by β-lactolin consumption. These results suggest that β-lactolin consumption prevents neural inflammation and alleviates aging-related cognitive decline.

β-Lactolin Enhances Neural Activity, Indicated by Event-Related P300 Amplitude, in Healthy Adults: A Randomized Controlled Trial

Background:

Epidemiological studies have shown that dairy product consumption is beneficial for cognitive function in elderly individuals. β-lactolin is a Gly–Thr–Trp–Tyr lacto-tetrapeptide rich in fermented dairy products that improves memory retrieval, attention, and executive function in older adults with subjective cognitive decline and prevents the pathology of Alzheimer’s disease in rodents. There has been no study on the effects of β-lactolin on neural activity in humans.

Objective:

We investigated the effects of β-lactolin on neural activity and cognitive function in healthy adults.

Methods:

In this randomized, double-blind, placebo-controlled study, 30 participants (45–64 years old) consumed β-lactolin or placebo for 6 weeks. Neural activity during auditory and language tasks was measured through 64-channel electroencephalography. Moreover, verbal fluency tests were performed at baseline and after 6 weeks.

Results:

The β-lactolin group had a significantly higher P300 amplitude at the Cp2 site (a part of the parietal lobe near the center of brain, p = 0.011), and C4 site (the area between the frontal and parietal lobe, p = 0.02) during the auditory tasks after 6 weeks than the placebo group. Thus, β-lactolin supplementation promoted neural activity in the parietal area, which increases concentration and attention during auditory cognitive tasks. Compared with the placebo group, the β-lactolin group also showed significant changes in the scores of verbal fluency test after 6 weeks (p = 0.033).

Conclusion:

Our findings provide insight into the mechanisms underlying the effects of β-lactolin on attention in healthy adults.

Effects of β-Lactolin on Regional Cerebral Blood Flow within the Dorsolateral Prefrontal Cortex during Working Memory Task in Healthy Adults: A Randomized Controlled Trial

Epidemiological studies have reported that consumption of dairy products rich in β-lactolin is beneficial for cognitive decline among elderly individuals. Although previous studies have shown that β-lactolin supplementation improves memory function and attention in healthy adults, the mechanism through which β-lactolin affects human brain function has yet to be elucidated. This placebo-controlled randomized double-blind study therefore examined the effects of β-lactolin on human regional cerebral blood flow (rCBF) using near-infrared spectroscopy (NIRS) according to the Consolidated Standards of Reporting Trials guidelines. A total of 114 healthy participants aged between 50 and 75 years with relatively low cognition were randomly allocated into the β-lactolin or placebo groups (n = 57 for both groups) and received supplementation for 6 weeks. After the 6 weeks of supplementation, total hemoglobin during cognitive tasks (Kraepelin and 2-back tasks) was measured using two-channel NIRS to determine rCBF. Accordingly, the β-lactolin group had significantly higher changes in total hemoglobin at the left dorsolateral prefrontal cortex (DLPFC) area measured using the left-side channel during the 2-back tasks (p = 0.027) compared to the placebo group. The present study suggests that β-lactolin supplementation increases rCBF and DLPFC activity during working memory tasks.