Association between intake of dairy products and short-term memory with and without adjustment for genetic and family environmental factors: A twin study

Potential neuroprotective effects of fermented foods and beverages in old age: a systematic review

Purpose

Numerous articles have recently studied the involvement of the gut microbiota in neurological diseases. Aging is associated with changes in the microbiome, which implies a reduction in microbial biodiversity among other changes. Considering that the consumption of a fermented-food diet improves intestinal permeability and barrier function, it seems of interest to study its participation in the prevention of neurodegenerative diseases. This article reviews existing studies to establish whether the consumption of fermented foods and fermented beverages prevents or ameliorates neurodegenerative decline in old age.

Methods

The protocol used was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Details of the protocol for this systematic review are registered on PROSPERO (CRD42021250921).

Results

Out of 465 articles identified in the Pubmed, Scopus, and Cochrane Library databases, a total of 29 that examined the relationship of the consumption of fermented products with cognitive impairment in old people were selected (22 cohort, 4 case-control, and 3 cross-sectional studies). The results suggest that low-to-moderate alcohol consumption and daily intake of coffee, soy products, and fermented-food diets in general are associated with a lower risk of dementia and Alzheimer's disease.

Conclusion

Daily consumption of fermented foods and beverages, either alone or as part of a diet, has neuroprotective effects and slows cognitive decline in old people.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=250921, identifier: CRD42021250921.

Association between Changes in Protein Intake and Risk of Cognitive Impairment: A Prospective Cohort Study

Little is known about the role of change in protein intake in affecting cognitive function among older adults. Therefore, we aimed to investigate the associations between the change in protein intake from various food groups and cognitive impairment among older adults in a prospective cohort study. A total of 6951 participants without cognitive impairment or dementia were included in this study. The frequency of protein intake from various food groups was measured by a food frequency questionnaire at baseline and follow-up. Multivariable Cox hazard models with time as the underlying time metric applied to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs). During the 37,535 person-years of follow-up, 1202 (17.3%) participants developed cognitive impairment. The improvement in overall protein intake was negatively associated with cognitive impairment with multivariable-adjusted HR of 0.98 (95% CI = 0.97-0.99). Compared with participants with stable change, those with an extreme decline in animal-based protein intake had a 48% higher risk of cognitive impairment. The associations of changes in protein from six food groups with cognitive impairment were in a similar direction to the main result. Protective associations between improving protein intake and a reduced risk of cognitive impairment were observed.

Application of Functional and Edible Coatings and Films as Promising Strategies for Developing Dairy Functional Products—A Review on Yoghurt Case

Edible coatings and films appear to be a very promising strategy for delivering bioactive compounds and probiotics in food systems when direct incorporation/inoculation is not an option. The production of dairy products has undergone radical modifications thanks to nanotechnology. Despite being a relatively new occurrence in the dairy sector, nanotechnology has quickly become a popular means of increasing the bioavailability and favorable health effects of a variety of bioactive components. The present review describes, in detail, the various processes being practiced worldwide for yoghurt preparation, microencapsulation, and nanotechnology-based approaches for preserving and/or enriching yoghurt with biologically, and its effect on health and in treating various diseases. In the case of yoghurt, as a perfect medium for functional ingredients supplementation, different gums (e.g., alginate, xanthan gum, and gum arabic), alone or in combination with maltodextrin, seem to be excellent coatings materials to encapsulate functional ingredients. Edible coatings and films are ideal carriers of bioactive compounds, such as antioxidants, antimicrobials, flavors, and probiotics, to improve the quality of dairy food products. Yoghurt is regarded as a functional superfood with a variety of health benefits, especially with a high importance for women’s health, as a probiotic. Consumption of yoghurt with certain types of probiotic strains which contain γ-linolenic acid or PUFA can help solve healthy problems or alleviate different symptoms, and this review will be shed light on the latest studies that have focused on the impact of functional yoghurt on women’s health. Recently, it has been discovered that fermented milk products effectively prevent influenza and COVID-19 viruses. Bioactive molecules from yoghurt are quite effective in treating various inflammations, including so-called “cytokine storms” (hypercytokinaemia) caused by COVID-19.

Dietary Patterns and Mild Cognitive Impairment Risk in Korean Adults over 50 Years Old

The prevalence of age-related diseases such as dementia and cognitive disorders is rapidly increasing. This study aimed to identify the dietary patterns associated with mild cognitive impairment (MCI) in adults aged over 50 years. This cross-sectional study investigated dietary patterns associated with cognitive function among older adults hospitalized in Gwangju province. Global cognitive function was assessed using the Mini-Mental State Examination. Diet information was obtained using a food frequency questionnaire with 112 food items and 24-h dietary recall. Using a principal component analysis, we identified three dietary patterns, “legumes and vegetables”, “beverage and nuts”, and “white rice”. The “beverage and nuts” pattern was inversely associated with the prevalence of high MCI after adjusting for covariates (third vs. first tertile, adjusted odds ratio: 0.333; 95% confidence interval: 0.133∼0.831; P<0.05). The white rice pattern was associated with the prevalence of MCI in the crude analysis. However, after adjusting for all confounding factors, no association was found. The “beverage and nuts” pattern was inversely associated with the prevalence of MCI. In the future, longitudinal population-based studies and randomized clinical trials are required to confirm the effect of potential dietary patterns on cognitive impairment and reveal the underlying mechanism of their association.

Milk and Dairy Products Intake Is Related to Cognitive Impairment at Baseline in Predimed Plus Trial

SCOPE

To examine the association between milk and dairy products intake and the prevalence of cognitive decline among Spanish individuals at high cardiovascular risk.

METHODS AND RESULTS

Cross-sectional analyses are performed on baseline data from 6744 adults (aged 55-75 years old). Intake of milk and dairy products is estimated using a food frequency questionnaire grouped into quartiles. The risk of developing cognitive impairment is based on the Mini-Mental State Examination (MMSE). A higher prevalence of cognitive decline was found in subjects who consumed more grams. Patients with worse MMSE score (10-24) consumed a mean of 395.14 ± 12.21 g, while patients with better MMSE score (27-30) consumed a mean of 341.23 ± 2.73 g (p < 0.05). Those subjects with the lower milk consumption (<220 g/day) had a higher MMSE score (28.35 ± 0.045). Higher intake of fermented dairy products was observed in participants with a lower MMSE score (OR 1.340, p = 0.003). A positive correlation was found between the consumption of whole milk and the MMSE score (r = 0.066, p < 0.001).

CONCLUSIONS

These findings suggest that greater consumption of milk and dairy products could be associated with greater cognitive decline according to MMSE. Conversely, consumption of whole-fat milk could be linked with less cognitive impairment in the cross-sectional study.

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.

Is milk and dairy intake a preventive factor for elderly cognition (dementia and Alzheimer's)? A quality review of cohort surveys

Milk and dairy (M&D) is a longstanding human food with widespread use. Many studies showed the preventive capacity of M&D in several human health disorders, but its utility in others is under discussion. Aging has been associated to elderly cognitive decline including dementia-Alzheimer syndrome (Dem-AD). The absence of a therapy to impede or postpone Dem-AD determines the need for its prevention, including nutritional factors. To evaluate the preventive capacity of M&D consumption in elderly Dem-AD we performed a systematic review in the main biomedical databases and information resources, but we present this study as a narrative review to discuss better the complexity of this subject. The elderly Dem-AD has a long pre-symptomatic period and the M&D intake has a widespread use. These determinants and the quality flaws of published studies impeach us to answer whether M&D consumption is preventive for Dem-AD. Moreover, two long Japanese cohorts suggest that M&D intake could prevent Dem-AD. Prospective cohorts beginning in midlife (or early life) could answer this question in the future.

Genetic Factors of Alzheimer's Disease Modulate How Diet is Associated with Long-Term Cognitive Trajectories: A UK Biobank Study

BACKGROUND

Fluid intelligence (FI) involves abstract problem-solving without prior knowledge. Greater age-related FI decline increases Alzheimer's disease (AD) risk, and recent studies suggest that certain dietary regimens may influence rates of decline. However, it is uncertain how long-term food consumption affects FI among adults with or without familial history of AD (FH) or APOE4 (ɛ4).

OBJECTIVE

Observe how the total diet is associated with long-term cognition among mid- to late-life populations at-risk and not-at-risk for AD.

METHODS

Among 1,787 mid-to-late-aged adult UK Biobank participants, 10-year FI trajectories were modeled and regressed onto the total diet based on self-reported intake of 49 whole foods from a Food Frequency Questionnaire (FFQ).

RESULTS

Daily cheese intake strongly predicted better FIT scores over time (FH-: β= 0.207, p < 0.001; ɛ4-: β= 0.073, p = 0.008; ɛ4+: β= 0.162, p = 0.001). Alcohol of any type daily also appeared beneficial (ɛ4+: β= 0.101, p = 0.022) and red wine was sometimes additionally protective (FH+: β= 0.100, p = 0.014; ɛ4-: β= 0.59, p = 0.039). Consuming lamb weekly was associated with improved outcomes (FH-: β= 0.066, p = 0.008; ɛ4+: β= 0.097, p = 0.044). Among at risk groups, added salt correlated with decreased performance (FH+: β= -0.114, p = 0.004; ɛ4+: β= -0.121, p = 0.009).

CONCLUSION

Modifying meal plans may help minimize cognitive decline. We observed that added salt may put at-risk individuals at greater risk, but did not observe similar interactions among FH- and AD- individuals. Observations further suggest in risk status-dependent manners that adding cheese and red wine to the diet daily, and lamb on a weekly basis, may also improve long-term cognitive outcomes.

Identification of a Novel Peptide from β-Casein That Enhances Spatial and Object Recognition Memory in Mice

An increase in the aging population has spurred recent efforts to identify diet and lifestyle changes that help prevent cognitive decline. Several epidemiological investigations and clinical studies have indicated that consuming fermented dairy products prevents cognitive decline. Some peptides from whey including β-lactolin improve memory impairment; the intake of Camembert cheese has been shown to prevent Alzheimer's in mouse models. To elucidate the molecular mechanisms underlying these preventive effects, we screened peptides from digested casein protein for their ability to improve spatial memory in a scopolamine-induced amnesia mouse model. Administration of KEMPFPKYPVEP peptide from β-casein at 0.5 mg/kg (54.8 ± 2.5) and 2 mg/kg (57.9 ± 3.7) improved memory impairment in the amnesia mice in comparison with control (44.9 ± 3.4; p = 0.031 and p = 0.042, respectively) and increased dopamine (5.9 ± 3.8 [control] and 12.4 ± 6.2 [KEMPFPKYPVEP peptide]) and norepinephrine (7.7 ± 0.8 [control] and 9.9 ± 2.0 [KEMPFPKYPVEP peptide]) levels in the frontal cortex (p = 0.039 and p = 0.031, respectively). Collectively, our findings suggest that peptides in fermented dairy products prevent cognitive decline and support previously reported observations.

Preventive Effects of Tryptophan-Methionine Dipeptide on Neural Inflammation and Alzheimer's Pathology

Preventive approaches for age-related memory decline and dementia have become a high priority in the aging society because of the lack of therapeutic approaches. Recent epidemiological studies have reported that fermented dairy products can help prevent dementia. Previously, we identified tryptophan-tyrosine (WY) and tryptophan-methionine (WM) peptides as the suppressants of activation of the primary microglia and showed that WY peptide consumption suppresses inflammation in the brains of Alzheimer's disease model mice. However, the effects of the WM peptide on inflammation in the brain and Alzheimer's pathology have not been investigated. Here, we evaluated the effect of WM peptide consumption on Alzheimer's disease model (5×FAD) mice. In 5×FAD mice, intake of WM peptide suppressed the production of inflammatory cytokines, activation of microglia, and infiltration of activated microglia around β amyloid (Aβ) depositions. WM peptide intake reduced Aβ deposition in the cortex and hippocampus and then improved the object recognition memory. Taken together with previous reports, the current findings indicate that ingestion of tryptophan-related peptides or food material rich in tryptophan-related peptides, thereby regulating microglial activity, represents a potential preventive approach for cognitive decline and dementia related to inflammation.

Supplementation With Whey Peptide Rich in β-Lactolin Improves Cognitive Performance in Healthy Older Adults: A Randomized, Double-Blind, Placebo-Controlled Study

Epidemiological reports showed that consumptions of fermented dairy products are beneficial for cognitive decline in elderly. Our previous preclinical studies have demonstrated that intakes of whey peptide rich in the β-lactolin [β-lactopeptide of glycine-thereonine-tryptophan-tyrosine (GTWY)] improve memory and attention by regulating monoamine system, and clinical study using neuropsychological test suggested that consumptions with GTWY-rich whey peptide enhance cognitive performance associated with the frontal cortex activity. However, corresponding interventional studies in humans are limited. Objectives: to evaluate the effects of the whey peptide on cognitive functions in healthy older adults using a randomized, double-blinded, placebo-controlled trial design. 114 healthy subjects aged 50–75 were supplemented with the whey peptide or placebo for 12 weeks, and changes in cognitive function were assessed using neuropsychological tests at weeks 0, 6, and 12 of the intervention. Neuropsychological tests included assessments for memory functions (subtests from Wechsler memory scale-revised, standard verbal paired-associate learning test, and recognition memory test for faces), assessments for attention (cancelation and detection tests), and assessments for general cognitive functions (repeatable battery for assessments of neuropsychological status). Cerebral blood flow was also assessed using near-infrared spectroscopy (NIRS) after 6 weeks of intervention. This study was registered on the 19 November, 2017 in the database of the University Hospital Medical Information Network (UMIN) prior to enrollment of subjects (Registration No. UMIN000030461: https://www.umin.ac.jp/ctr/index-j.htm). In the whey peptide group, visual paired-associates I and visual cancelation tests were significantly improved compared with those in the placebo group at weeks 6 and 12 of the intervention, respectively. Visuospatial and constructional scores of the repeatable battery for assessments of neuropsychological status and standard verbal paired-associate learning tests (S-PA) also tended to be improved by the intervention at week 12. Daily intakes of GTWY-rich whey peptide show beneficial effects on cognitive performance, especially associative learning memory and control of attention, in healthy older adults and might prevent age-related cognitive declines.

Tryptophan-Tyrosine Dipeptide, the Core Sequence of β-Lactolin, Improves Memory by Modulating the Dopamine System

Tryptophan-tyrosine (WY)-related peptides including the β-lactopeptide of the glycine-threonine-tryptophan-tyrosine peptide, β-lactolin, improve spatial memory. However, whether and how the WY dipeptide as the core sequence in WY-related peptides improves memory functions has not been investigated. This study assessed the pharmacological effects of the WY dipeptide on memory impairment to elucidate the mechanisms. Here, we showed that oral administration of dipeptides of WY, tryptophan-methionine (WM), tryptophan-valine, tryptophan-leucine, and tryptophan-phenylalanine improved spontaneous alternation of the Y-maze test in scopolamine-induced amnesic mice. In contrast, tyrosine-tryptophan, methionine-tryptophan, tryptophan, tyrosine, and methionine had no effect. These results indicated that the conformation of dipeptides with N-terminal tryptophan is required for their memory improving effects. WY dipeptide inhibited the monoamine oxidase B activity in vitro and increased dopamine levels in the hippocampus and frontal cortex, whereas tryptophan did not cause these effects. In addition, the treatment with SCH-23390, a dopamine D1-like receptor antagonist, and the knockdown of the hippocampal dopamine D1 receptor partially attenuated the memory improvement induced by the WY dipeptide. Importantly, WY dipeptide improved the spontaneous alternations of the Y-maze test in aged mice. These results suggest that the WY dipeptide restores memory impairments by augmenting dopaminergic activity. The development of supplements rich in these peptides might help to prevent age-related cognitive decline.

Perspectives on the production of milk on small-holder dairy farms and its utilisation in developing countries

The profitability of milk production in the developing world varies widely among farming systems. This results from poor animal productivity and an inefficient marketing-chain structure in which farmers seldom profit from their dairying activities. The lack of chilling facilities for milk storage and the need to adulterate the raw product along the market chain to enhance profit margins means that consumers are not well catered for. Co-operative selling of milk, along with the acquisition of higher-quality feeds and veterinary medicines, has boosted the financial resilience of small-holder farming communities worldwide, although, in many regions, the co-operative model has not succeeded largely through a lack of trust between families even within the communities. Commercial reality dictates that farming communities work together to achieve financial sustainability, although the model adopted for each community may differ. Although milk has traditionally provided many consumers with their only source of animal protein, vitamin and minerals, we are now discovering its many other virtues, particularly in relation to cognitive development and memory retention and the provision of antioxidants. The impact of milk-processing technology on some of these remarkable properties requires further investigation to ensure that milk consumers worldwide benefit from these positive attributes.

Novel lactopeptides in fermented dairy products improve memory function and cognitive decline

Alongside the rapid growth in aging populations, prevention of age-related memory decline and dementia has become a high priority. Several epidemiological and clinical studies have concluded that fermented dairy products can help to prevent cognitive decline; furthermore, intake of Camembert cheese prevents Alzheimer's pathology in model mice. To elucidate molecular mechanisms underlying the preventive effects of fermented dairy products, here we screened peptides from digested fermented dairy products for ability to improve memory function in a scopolamine-induced amnesia mouse model. We found that Trp-Tyr (WY)-containing peptides from whey protein improved memory function in the mice, and the effects were confirmed in aged mice. The WY-containing peptides directly inhibited monoamine oxidase-B activity and increased dopamine levels in brain tissue. Pretreatment with dopamine receptor antagonist abolished the improvement in memory function due to WY-containing peptides. These results suggest that WY-containing peptides in fermented dairy products increase monoamine levels by inhibiting monoamine oxidase-B activity, helping to prevent age-related cognitive decline.

Effect of Supplementation of a Whey Peptide Rich in Tryptophan-Tyrosine-Related Peptides on Cognitive Performance in Healthy Adults: A Randomized, Double-Blind, Placebo-Controlled Study

Background: Previous epidemiological and clinical studies have shown that dairy products have beneficial effects on cognitive decline and dementia. Enzymatic digestion of whey protein produces a whey peptide rich in tryptophan-tyrosine-related peptides which improve cognitive performance in mice. We evaluated the effects of whey peptides on cognitive functions in healthy adults in a randomized, double-blind, placebo-controlled design. Methods: 101 healthy adults (45 to 64 years), with a self-awareness of cognitive decline received either whey peptide or placebo supplements for 12 weeks. Changes in cognitive function were assessed using neuropsychological tests at 6 and 12 weeks after the start of supplementation. Results: Verbal fluency test (VFT) score changes tended to be higher in the whey peptide group compared with the placebo at 12 weeks. Subgroup analysis classified by the degree of subjective fatigue showed that changes in the VFT as well as the Stroop and subjective memory function tests between baseline and 6 weeks of intervention were significantly better in subjects with high-level fatigue from the whey peptide group as compared to the placebo group.

CONCLUSIONS

Intake of whey peptide might improve cognitive function in healthy middle- and older-aged adults with high subjective fatigue levels. Further studies will elucidate the relationship among cognitive improvement, whey peptides, and psychological fatigue.

Preventive Effects of Dairy Products on Dementia and the Underlying Mechanisms

Alongside the rapid population aging occurring worldwide, the prevention of age-related memory decline and dementia has become a high priority. Dairy products have many physiological effects owing to their contents of lactic acid bacteria and the fatty acids and peptides generated during their fermentation. In particular, several recent studies have elucidated the effects of fermented dairy products on cognitive function. Epidemiological and clinical evidence has indicated that fermented dairy products have preventive effects against dementia, including Alzheimer’s disease. Recent preclinical studies have identified individual molecules generated during fermentation that are responsible for those preventive effects. Oleamide and dehydroergosterol have been identified as the agents responsible for reducing microglial inflammatory responses and neurotoxicity. In this review, the protective effects of fermented dairy products and their components on cognitive function, the mechanisms underlying those effects, and the prospects for their future clinical development will be discussed.

A Mediterranean Diet to Improve Cardiovascular and Cognitive Health: Protocol for a Randomised Controlled Intervention Study

The Mediterranean diet has demonstrated efficacy for improving cardiovascular and cognitive health. However, a traditional Mediterranean diet delivers fewer serves of dairy and less dietary calcium than is currently recommended in Australia, which may limit long-term sustainability. The present study aims to evaluate whether a Mediterranean diet with adequate dairy and calcium can improve cardiovascular and cognitive function in an at-risk population, and thereby reduce risk of cardiovascular disease (CVD) and cognitive decline. A randomised, controlled, parallel, crossover design trial will compare a Mediterranean diet supplemented with dairy foods against a low-fat control diet. Forty participants with systolic blood pressure above 120 mmHg and at least two other risk factors of CVD will undertake each dietary intervention for eight weeks, with an eight-week washout period between interventions. Systolic blood pressure will be the primary measure of interest. Secondary outcomes will include measures of cardiometabolic health, dietary compliance, cognitive function, assessed using the Cambridge Neuropsychological Test Automated Battery (CANTAB), psychological well-being and dementia risk. This research will provide empirical evidence as to whether the Mediterranean diet can be modified to provide recommended dairy and calcium intakes while continuing to deliver positive effects for cardiovascular and cognitive health. The findings will hold relevance for the field of preventative healthcare and may contribute to revisions of national dietary guidelines.

Association between subjective memory complaints and depressive symptoms after adjustment for genetic and family environmental factors in a Japanese twin study

OBJECTIVES

The aim of this study was to investigate the association between subjective memory complaints (SMCs) and depressive symptoms, with and without adjustment for genetic and family environmental factors.

METHODS

We conducted a cross-sectional study using twins and measured SMCs and depressive symptoms as outcomes and explanatory variables, respectively. First, we performed regression analyses using generalized estimating equations to investigate the associations between SMCs and depressive symptoms without adjustment for genetic and family environmental factors (individual-level analyses). We then performed regression analyses for within-pair differences using monozygotic (MZ) and dizygotic (DZ) twin pairs and MZ twin pairs to investigate these associations with adjustment for genetic and family environmental factors by subtracting the values of one twin from those of co-twin variables (within-pair level analyses). Therefore, differences between the associations at individual- and within-pair level analyses suggested confounding by genetic factors.

RESULTS

We included 556 twins aged ≥ 20 years. In the individual-level analyses, SMCs were significantly associated with depressive symptoms in both males and females [standardized coefficients: males, 0.23 (95% CI 0.08-0.38); females, 0.35 (95% CI 0.23-0.46)]. In the within-pair level analyses using MZ and same-sex DZ twin pairs, SMCs were significantly associated with depressive symptoms. In the within-pair level analyses using the MZ twin pairs, SMCs were significantly associated with depressive symptoms [standardized coefficients: males, 0.32 (95% CI 0.08-0.56); females, 0.24 (95% CI 0.13-0.42)].

CONCLUSIONS

This study suggested that SMCs were significantly associated with depressive symptoms after adjustment for genetic and family environmental factors.