Dairy consumption and working memory performance in overweight and obese adults

Effectiveness of exercise interventions, alone or in combination with dietary modifications, on working memory in overweight and obese individuals: A systematic review

This systematic review aimed to establish the effectiveness of exercise interventions, alone or in combination with dietary modifications, on working memory (WM) in individuals living with overweight and obesity. A comprehensive literature search was conducted using the Scopus, PubMed, Springer-Link, RefSeek, and Cochrane Library databases to identify relevant publications up to January 18, 2024. Data on participants' characteristics, intervention settings, and key outcomes related to WM were extracted. The quality of the studies was assessed using the PEDro scale. A total of 15 articles met pre-established inclusion criteria, involving participants across nine countries with a range of 12-125 individuals and ages spanning from 6 to 80 years old. Among the studies analyzed, 10 exclusively investigated exercise interventions, whereas five explored the combined effects. Notably, 70% of the exercise interventions (7 out of 10) exhibited positive improvements in WM. Likewise, 60% of the combined interventions (3 out of 5) demonstrated favorable enhancements in WM. No differences were found between the two protocols. Common features between the protocols were identified and described. Both protocols showed favorable and promising effects on WM in this clinical population. Nonetheless, the limited evidence addressing the combination of exercise and diet in the same research approach reduces the generalizability of the findings. This review offers valuable insights for future clinical and research applications in people with overweight and obesity.

Effects of resistance exercise and whey protein supplementation on cognitive function in older men: secondary analysis of a randomised, double-blind, placebo-controlled trial

PURPOSE

Ageing is associated with cognitive decline. This study investigated the individual and combined effects of resistance exercise (RE) and whey protein supplementation (PRO) on cognitive function in older men.

METHODS

In a pooled-groups analysis, 36 older men (age: 67 ± 4 years) were randomised to either RE (2 x/week; n = 18) or no exercise (NE; n = 18), and either PRO (2 × 25 g/d whey protein isolate; n = 18) or control (CON, 2 × 23.75 g maltodextrin/d; n = 18). A sub-analysis was also conducted between RE + CON (n = 9) and RE + PRO (n = 9). At baseline and 12 weeks, participants completed a battery of neuropsychological tests (CANTAB; Cambridge Cognition, UK) and neurobiological, inflammatory, salivary cortisol and insulin sensitivity biomarkers were quantified.

RESULTS

PRO improved executive function z-score (+0.31 ± 0.08) greater than CON (+0.06 ± 0.08, P = 0.03) and there was a trend towards improved global cognitive function (P = 0.053). RE and RE + PRO did not improve any cognitive function domains (p ≥ 0.07). RE decreased tumor necrosis factor-alpha (P = 0.02) and interleukin-6 (P = 0.048) concentrations compared to NE, but changes in biomarkers did not correlate with changes in cognitive domains. Muscle strength (r = 0.34, P = 0.045) and physical function (ρ = 0.35-0.51, P < 0.05) outcomes positively correlated with cognitive function domains at baseline, but only Δskeletal muscle index correlated with Δepisodic memory (r = 0.34, P = 0.046) following the intervention.

CONCLUSION

In older men, PRO improved cognitive function, most notably executive functioning. RE did not improve any cognitive function domains but did decrease biomarkers of systemic inflammation. No synergistic effects were observed.

Association between breakfast patterns and executive function among adolescents in Shanghai, China

Introduction

The aim of this cross-sectional study was to investigate the association between breakfast patterns and executive function among adolescents in Shanghai, China.

Methods

In 2022, we randomly recruited 3,012 adolescents aged 12-13 years from all administrative districts in Shanghai. Breakfast information was collected by parents using a one-day recall method. Executive function was measured using the Behavior Rating Inventory of Executive Function-Parent Version. Latent Class Analysis was performed to identify breakfast patterns based on the food groups in the Diet Quality Questionnaire for China.

Results

Breakfast patterns were classified into three categories: "Egg and milk foods", "Grain foods", and "Abundant foods", except for adolescents who skipped breakfast. Logistic regression was used to estimate the multivariate odds ratio (ORs) and 95% confidence intervals (95% CI) for the association between breakfast patterns and potential executive dysfunction. Adolescents in the "Abundant foods" class had a lower risk of executive dysfunction in terms of initiate (OR: 0.36; 95% CI: 0.17-0.76), and organization of materials (OR: 0.18; 95% CI: 0.04-0.94), compared to those who skipped breakfast. Similarly, the breakfast patterns of "Grain foods" and "Egg and milk foods" were associated with a lower risk of executive dysfunction, including initiate and working memory.

Discussion

Our findings suggest that breakfast patterns were associated with executive function. The improvement of breakfast patterns among adolescents should be a significant public health intervention.

Elateriospermum tapos Yoghurt as a Therapeutic Intervention for Obesity-Associated Cognitive Impairments and Anxiety-like Behaviour in a High Fat Diet Maternal Obese Rat Model

Maternal obesity can be considered an intergenerational cycle and is also an important indicator of cognitive impairments. It is thought that using natural products is the best and safest way to combat maternal obesity and associated complications. Recent studies have shown that Elateriospermum tapos (E. tapos) contains bioactive compounds with anti-obesity effects, and yoghurt is a convenient medium for supplementing obese maternal rats with E. tapos extract. Thus, the aim of this study is to investigate the impact of E. tapos in yoghurt on maternally obese rats' cognitive function supplemented with a high-fat diet (HFD). In this study, 48 female Sprague-Dawley rats were used. The rats were fed HFD for a period of 16 weeks to induce obesity, after which they were allowed to mate. Upon confirmation of pregnancy, obese rats were given varying doses of E. tapos (5, 50, and 500 mg/kg) in yoghurt until postnatal (PND) day 21. On PND 21, the dams' body mass index (BMI), Lee index, abdominal circumference, oxidative status, and metabolic profile were measured. The behavioral tests (open field, place, and object recognition) were conducted on PND 21 to access memory. The results show that the 50 and 500 mg/kg E. tapos in yoghurt supplemented groups had similar BMI, Lee index, abdominal circumference, lipid profile, FBG, insulin, FRAP, and GSH levels, as well as a similar recognition index, in comparison with the control group supplemented with saline. In conclusion, the results of this study indicate that the newly formulated E. tapos in yogurt can act as an anti-obesity agent in maternal obesity, alleviate anxiety, and enhance hippocampal-dependent memory.

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

The EAT-Lancet Commission devised a sustainable reference diet with the aim of reducing the incidence of non-communicable diseases and mortality globally while improving food system sustainability. The extent to which the reference diet supports cognitive function across the life course, however, has not yet been evaluated. This Review assesses the evidence for diet supporting cognitive function from childhood into old age. A comprehensive but non-exhaustive literature search was done, synthesising studies that investigated the effect of whole foods on cognition in healthy, community-dwelling human participants. We found that the current evidence base is weak with mixed conclusions and multiple methodological caveats, which precludes strong conclusions pertaining to the suitability of dietary recommendations for each food group per age group. Long-term intervention and prospective cohort studies are needed to reduce this knowledge deficit. Revising dietary recommendations with the aim of maintaining an adequate nutrient intake to sustain healthy cognitive function across the life course could be worthwhile. This Review outlines recommendations for future work to help improve the current knowledge deficit regarding dietary intake and cognitive function across the life course and its implications for dietary guidelines such as the EAT-Lancet Commission.

Effect of Dietary Intake Through Whole Foods on Cognitive Function: Review of Randomized Controlled Trials

PURPOSE OF REVIEW

This review evaluated recent randomized controlled trials (RCTs) examining the chronic intake of whole foods associated with the Mediterranean, Dietary Approaches to Stop Hypertension (DASH), Mediterranean-DASH Intervention for Neurogenerative Delay (MIND), and ketogenic (KETO) diets on cognitive function.

RECENT FINDINGS

We identified RCTs related to olive oil (N = 3), nuts (N = 7), fatty fish (N = 1), lean meats (N = 4), fruits and vegetables (N = 9), legumes (N = 1), and low-fat dairy (N = 4), with 26/29 reporting positive results on at least one measure of cognition. We also identified 6 RCTs related to whole food-induced KETO diets, with half reporting positive effects on cognition. Variations in study design (i.e., generally the studies are < 6 months and include middle-aged and older, cognitively intact participants) and small sample sizes make it difficult to draw conclusions across studies; however, the current evidence from RCTs generally supports individual component intakes of these dietary patterns as an effective, nonpharmacological approach to improve cognitive health in adults.

Milk, yogurt and cheese intake is positively associated with cognitive executive functions in older adults of the Canadian Longitudinal Study on Aging

BACKGROUND

Dairy products provide essential nutrients such as calcium, vitamins B12 and D, and include bioactive peptides and fermented products, which may be beneficial for cognition, especially in older adults. Yet, few studies of large contemporary cohorts have investigated this relationship using sensitive domain-specific cognitive tests.

METHODS

In community-dwelling older adults of the Canadian Longitudinal Study on Aging (2011-2015), we examined cross-sectional associations between total and specific dairy product intake and performance in three cognitive domains (executive functions, memory, psychomotor speed). Cheese, milk, yogurt, regular-fat, low-fat and fermented dairy product intake frequencies were estimated using a food frequency questionnaire; participants were classified into quartiles. MANCOVA models were applied to estimate differences.

RESULTS

In 7,945 participants (65-86 y, 49% women, 97% Caucasian), the mean dairy product intake was 1.9 (1.1) times/d. Total dairy product, cheese and low-fat dairy product intake were positively associated with the executive function domain and yogurt intake with the memory domain (all p<0.05), independently of important covariates including age, gender, education and diet quality. Intakes of total dairy product, cheese and low-fat dairy were associated with verbal fluency specifically (all p<0.05). Participants with a dairy product intake > 2.5 times/d had a higher score compared to those consuming less. No associations were found with psychomotor speed.

CONCLUSIONS

This large cohort study suggests a specific role for dairy components in executive function phonemic verbal fluency and memory. Dairy product intake, a modifiable factor, may be targeted in cognitive health-promoting interventions.

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.

Effect of dairy intake with or without energy restriction on body composition of adults: overview of systematic reviews and meta-analyses of randomized controlled trials

CONTEXT

Some studies suggest that consumption of dairy products can aid in weight loss, while others suggest a negative effect or no effect.

OBJECTIVE

An overview of systematic reviews and meta-analyses was conducted to examine the effect of dairy product consumption on changes in body composition.

DATA SOURCES

PRISMA guidelines were followed to ensure transparent reporting of evidence. The MEDLINE, Embase, Cochrane Central Database of Systematic Reviews, and Web of Science databases were searched from inception to April 2018.

STUDY SELECTION

Six systematic reviews and 47 associated meta-analyses (which included the results of 58 different randomized controlled trials) published in English or Spanish and reporting data on dairy intake and changes in weight, fat mass, lean mass, or waist circumference were included.

DATA EXTRACTION

Two authors independently extracted the data and assessed the risk of bias using the AMSTAR2 tool.

RESULTS

Dairy consumption interventions without dietary energy restriction had no significant effects on weight, fat mass, lean mass, or waist circumference. Interventions in energy-restricted settings had significant effects on fat mass and body weight.

CONCLUSIONS

Increasing total dairy intake without energy restriction in adults does not affect body composition. In the context of an energy-restricted diet, however, increased dairy intake results in lower fat mass and body weight but has no conclusive effects on waist circumference or lean mass.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number CRD42018094672.

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.

Interventions involving a major dietary component improve cognitive function in cognitively healthy adults: a systematic review and meta-analysis

Accumulating evidence suggests a role for diet in promoting brain health. The purpose of this systematic review was to (1) quantitatively assess whether interventions with a major dietary component can enhance cognition in cognitively healthy adults and (2) identify responsive domains of cognition to inform the design of future dietary trials. Electronic databases were systematically searched to find eligible randomized controlled trials that assessed the effect of interventions with a major dietary component on cognitive function or incident dementia in adults without known cognitive impairment. Standardized mean differences (SMDs) (95% confidence interval [CI]) were combined using a random-effects meta-analysis, and tests of homogeneity of variance were calculated. Two trials reported dementia outcomes and were qualitatively described. Fifteen trials encompassing 6480 participants were eligible for meta-analysis. Compared to control, intervention improved performance on measures of global cognition (SMD = 0.14, 95% CI 0.01-0.27, P = .05, I² 76%), executive function (SMD = 0.11, 95% CI 0.04-0.18, P = .003, I² 0%), and processing speed (SMD = 0.12, 95% CI 0.05-0.19, P = .001, I² 0%). There was no effect of intervention on delayed memory (SMD = 0.04, 95% CI -0.02 to 0.09, P = .18, I² 4%). Significant heterogeneity and funnel plot asymmetry were detected for global cognition, but removal of studies with high risk of bias did not change the pooled findings. Current evidence is limited but indicates that diverse interventions improve nonmemory cognitive functions during normal cognitive aging. Measures of executive function and processing speed should be considered as feasible end points in future dietary intervention trials.

Role of milk and dairy intake in cognitive function in older adults: a systematic review and meta-analysis

BACKGROUND

As aging populations increase across the globe, research on lifestyle factors that prevent cognitive decline and dementia is urgently needed. Therefore, a systematic review was conducted to examine the effects of varying levels of milk intake alone or in combination with other dairy products on the outcomes of cognitive function and disorders in adults.

METHODS

A comprehensive search was conducted across 3 databases (PUBMED, CINAHL, and EMBASE) from their inception through October 2017. Prospective cohort studies and randomized controlled trials (RCTs) that enrolled adults were included. Studies with follow-up durations of less than 4 weeks and studies including schizophrenic patients were excluded. Two independent investigators conducted abstract and full-text screenings, data extractions, and risk-of-bias (ROB) assessments using validated tools. Studies were synthesized qualitatively using a strength of evidence (SoE) rating tool. A random-effects model for meta-analysis was conducted when at least 3 unique studies reported sufficient quantitative data for the same outcome.

RESULTS

A total of 1 RCT and 7 cohort studies were included. One medium-quality small RCT (n = 38 participants) showed that only spatial working memory was marginally better in the high dairy diet group compared to the low dairy diet group. Two of the 7 cohort studies were rated as having a high ROB, and only 1 cohort study was rated as having a low ROB. There were large methodological and clinical heterogeneities, such as the methods used to assess milk or dairy intake and the characteristics of the study populations. It was impossible to conduct a dose-response meta-analysis because the studies utilized different categories of exposures (e.g., different frequencies of milk consumption or the amount of dairy intake). Thus, the overall SoE was rated as insufficient regarding the associations between milk intake and cognitive decline, dementia, and Alzheimer's disease outcomes. Our meta-analysis of 3 cohort studies showed no significant association between milk intake and cognitive decline outcome (pooled adjusted risk ratio = 1.21; 95% CI: 0.81, 1.82; for highest vs. lowest intake) with large statistical heterogeneity (I2 = 64.1%).

CONCLUSIONS

The existing evidence (mostly observational) is too poor to draw a firm conclusion regarding the effect of milk or dairy intake on the risk of cognitive decline or disorders in adults.

Interplay Between the Gut-Brain Axis, Obesity and Cognitive Function

Obesity continues to be one of the major public health problems due to its high prevalence and co-morbidities. Common co-morbidities not only include cardiometabolic disorders but also mood and cognitive disorders. Obese subjects often show deficits in memory, learning and executive functions compared to normal weight subjects. Epidemiological studies also indicate that obesity is associated with a higher risk of developing depression and anxiety, and vice versa. These associations between pathologies that presumably have different etiologies suggest shared pathological mechanisms. Gut microbiota is a mediating factor between the environmental pressures (e.g., diet, lifestyle) and host physiology, and its alteration could partly explain the cross-link between those pathologies. Westernized dietary patterns are known to be a major cause of the obesity epidemic, which also promotes a dysbiotic drift in the gut microbiota; this, in turn, seems to contribute to obesity-related complications. Experimental studies in animal models and, to a lesser extent, in humans suggest that the obesity-associated microbiota may contribute to the endocrine, neurochemical and inflammatory alterations underlying obesity and its comorbidities. These include dysregulation of the HPA-axis with overproduction of glucocorticoids, alterations in levels of neuroactive metabolites (e.g., neurotransmitters, short-chain fatty acids) and activation of a pro-inflammatory milieu that can cause neuro-inflammation. This review updates current knowledge about the role and mode of action of the gut microbiota in the cross-link between energy metabolism, mood and cognitive function.

Why Is Working Memory Performance Unstable? A Review of 21 Factors

In this paper, we systematically reviewed twenty-one factors that have been shown to either vary with or influence performance on working memory (WM) tasks. Specifically, we review previous work on the influence of intelligence, gender, age, personality, mental illnesses/medical conditions, dieting, craving, stress/anxiety, emotion/motivation, stereotype threat, temperature, mindfulness training, practice, bilingualism, musical training, altitude/hypoxia, sleep, exercise, diet, psychoactive substances, and brain stimulation on WM performance. In addition to a review of the literature, we suggest several frameworks for classifying these factors, identify shared mechanisms between several variables, and suggest areas requiring further investigation. This review critically examines the breadth of research investigating WM while synthesizing the results across related subfields in psychology.

Nutrition and Cognition in Older Adults With Heart Failure: A Systematic Review

Cognitive impairment is commonly observed in older adults with heart failure; nutrition is a possible contributing factor. The purpose of the current systematic review is to examine the relationship between nutrition and cognition in older adults with heart failure. A literature review was performed through August 2015 that examined published, peer-reviewed studies from PubMed, PsycINFO, CINAHL, and Web of Science. Four articles were selected for inclusion. Findings revealed that poorer nutritional habits were associated with poorer attention, executive functioning, and memory in older adults with heart failure. Nutritional biomarkers, including anemia, hyponatremia, hypokalemia, hyperglycemia, and hypoalbuminemia, were also associated with cognitive impairment. More research is needed to explore the relationship between nutrition and cognition in this population. Descriptive studies will inform scientists as they design and test nutritional interventions to optimize cognitive function in older adults with heart failure.

Effect of increasing dietary calcium through supplements and dairy food on body weight and body composition: a meta-analysis of randomised controlled trials

This meta-analysis of randomised controlled trials assessed the effect of Ca on body weight and body composition through supplementation or increasing dairy food intake. Forty-one studies met the inclusion criteria (including fifty-one trial arms; thirty-one with dairy foods (n 2091), twenty with Ca supplements (n 2711). Ca intake was approximately 900 mg/d higher in the supplement groups compared with control. In the dairy group, Ca intake was approximately 1300 mg/d. Ca supplementation did not significantly affect body weight (mean change ( - 0·17, 95% CI - 0·70, 0·37) kg) or body fat (mean change ( - 0·19, 95% CI - 0·51, 0·13) kg) compared to control. Similarly, increased dairy food intake did not affect body weight ( - 0·06, 95% CI - 0·54, 0·43) kg or body fat change ( - 0·36, 95% CI - 0·80, 0·09) kg compared to control. Sub-analyses revealed that dairy supplementation resulted in no change in body weight (nineteen studies, n 1010) ( - 0·32, 95% CI - 0·93, 0·30 kg, P= 0·31), but a greater reduction in body fat (thirteen studies, n 564) ( - 0·96, 95% CI - 1·46, - 0·46 kg, P < 0·001) in the presence of energy restriction over a mean of 4 months compared to control. Increasing dietary Ca intake by 900 mg/d as supplements or increasing dairy intake to approximately 3 servings daily (approximately 1300 mg of Ca/d) is not an effective weight reduction strategy in adults. There is, however, an indication that approximately 3 servings of dairy may facilitate fat loss on weight reduction diets in the short term.

The role of gangliosides in neurodevelopment

Gangliosides are important components of neuronal cell membranes and it is widely accepted that they play a critical role in neuronal and brain development. They are functionally involved in neurotransmission and are thought to support the formation and stabilization of functional synapses and neural circuits required as the structural basis of memory and learning. Available evidence, as reviewed herein, suggests that dietary gangliosides may impact positively on cognitive functions, particularly in the early postnatal period when the brain is still growing. Further, new evidence suggests that the mechanism of action may be through an effect on the neuroplasticity of the brain, mediated through enhanced synaptic plasticity in the hippocampus and nigro-striatal dopaminergic pathway.

Dairy intake is associated with memory and pulsatility index in heart failure

PURPOSE/AIM

Past work shows an inconsistent relationship between dairy intake and cognition in healthy older adults. A cross-sectional design was conducted to examine dairy consumption, cognitive dysfunction, and cerebral blood flow in a sample of older adults with heart failure (HF) to clarify their association in this population at high risk for adverse neurocognitive outcomes.

MATERIALS AND METHODS

A total of 86 older adults with HF (70.39 ± 9.51 years; 33.1% female) underwent neuropsychological testing, transcranial Doppler (TCD) sonography to quantify cerebral blood flow. Dairy intake was quantified using a brief self-report questionnaire.

RESULTS

Partial correlations between the dairy consumption questionnaire and neuropsychological tests were conducted adjusting for HF severity, age, and sex. Contrary to expectations, results showed greater dairy intake was associated with poorer memory (r = -0.21, p = 0.01) and higher pulsatility index in the medial cerebral artery (r = -0.17, p = 0.05).

CONCLUSION

Results suggest that greater dairy intake was associated with poorer memory performance in older adults with HF. Several possible explanations for these findings exist, including the contribution of high-fat dairy to underlying physiological processes that promote vascular cognitive impairment. Prospective studies employing objective measures specific to high and low fat dairy are needed to clarify this possibility.

Dairy food intake is positively associated with cardiovascular health: findings from Observation of Cardiovascular Risk Factors in Luxembourg study

Conflicting findings have been reported about dairy food consumption and risk for cardiovascular disease. Furthermore, few studies have examined dairy food intake in relation to cardiovascular health and the incorporation of lifestyle factors such as diet and physical activity. This study examined whether dairy food consumption was associated with cardiovascular health, recently defined by the American Heart Association. Data were analyzed from 1352 participants from the Observation of Cardiovascular Risk Factors in Luxembourg survey. A validated food frequency questionnaire was used to measure intakes of milk, yogurt, cheese, dairy desserts, ice cream, and butter. Seven cardiovascular health metrics were assessed: smoking, body mass index, physical activity, diet, total cholesterol, blood pressure, and fasting plasma glucose. A total cardiovascular health score (CHS) was determined by summing the total number of health metrics at ideal levels. It was hypothesized that greater dairy food consumption (both low fat and whole fat) would be associated with better global cardiovascular health, as indicated by a higher CHS. Total dairy food intake was positively associated with the CHS. Higher intakes of whole fat milk, yogurt, and cheese were associated with better cardiovascular health. Even when controlling for demographic and dietary variables, those who consumed at least 5 servings per week of these dairy products had a significantly higher CHS than those who consumed these products less frequently. Higher total whole fat dairy food intake was also associated with other positive health behaviors, including being a nonsmoker, consuming the suggested dietary intakes of recommended foods, and having a normal body mass index. Increased dairy food consumption was associated with better cardiovascular health.

Dietary antioxidants, cognitive function and dementia--a systematic review

Antioxidant compounds, contained in fruit, vegetables and tea, have been postulated to have a protective effect against age-related cognitive decline by combating oxidative stress. However, recent research on this subject has been conflicting. The aim of this systematic review was to consider current epidemiological and longitudinal evidence for an association between habitual dietary intake of antioxidants and cognition, with consideration given to both cognitive functioning and risk for dementia and its subtypes, including Alzheimer's disease and vascular dementia. Searches of electronic databases were undertaken to identify peer-reviewed journal articles that reported on associations between antioxidant intakes (vitamins C, E, flavonoids, carotenoids) and cognitive function or risk for dementia. Eight cross-sectional and 13 longitudinal studies were identified and included in the review. There were mixed findings for the association between antioxidant intake, cognition and risk of dementia and Alzheimer's disease. Large heterogeneity in study design, differential control of confounders, insufficient measures of cognitive performance, and difficulties associated with dietary assessment may contribute to the inconsistent findings. Overall, findings do not consistently show habitual intakes of dietary antioxidants are associated with better cognitive performance or a reduced risk for dementia. Future intervention trials are warranted to elucidate the effects of a high intake of dietary antioxidants on cognitive functioning, and to explore effects within a whole dietary pattern.

Long-term dietary intervention trials: critical issues and challenges

BACKGROUND

There are many challenges involved in running randomised controlled dietary intervention trials that investigate health outcomes. The aim of this paper was to evaluate the recruitment process, retention of participants and challenges faced in our dairy intervention trial, and to provide strategies to combat the difficulties of running long-term dietary intervention trials.

METHODS

A 12-month, randomised, two-way crossover study was conducted in overweight adults with habitually low dairy food consumption to assess the effects of a high dairy intake (4 servings of reduced-fat dairy per day) compared with a low dairy intake (1 serving of reduced-fat dairy per day) on measures of cardiometabolic and cognitive health. On completion of the high dairy intake phase, each participant was interviewed about their experience in the trial and responses were used to evaluate the key issues for study participants.

RESULTS

Although the recruitment target was achieved, high rates of attrition (49.3%) and difficulties maintaining participant compliance (reported by 37.8% of participants) were major threats to the viability of the study. Factors that contributed to the high attrition included inability to comply with the dietary requirements of the study protocol (27.0%), health problems or medication changes (24.3%) and time commitment (10.8%).

CONCLUSION

Attrition and adherence to study requirements present challenges to trials requiring longer-term dietary change. Including a run-in period to further assess the motivation, commitment and availability of participants, maintaining regular contact with participants during control phases, minimising time commitment, providing flexibility with dietary requirements, facilitating positive experiences, and stringent monitoring of diet are some key recommendations for future dietary intervention trials.

TRIAL REGISTRATION

Australia and New Zealand Clinical Trials Registry (ACTRN 12608000538347).

Cognitive deficits, obesity and disability in schizophrenia

Despite 50 years of pharmacological and psychosocial interventions schizophrenia remains one of the leading causes of disability. The inability to function in everyday settings includes deficits in performance of social, occupational, and independent living activities. Schizophrenia is also a life-shortening illness, caused mainly by poor physical health and its complications. Dysfunctional lifestyles including sedentary behavior and lack of physical activity prevail, while treatment with adipogenic antipsychotic medication interacts with poor performance in screening, monitoring, and intervention that result in shortening of life expectancies by 25–30 years. Disability interferes with self-care and medical care, further worsening physical health to produce a vicious cycle of disability. Further, the neurobiological impact of obesity on brain functioning is substantial and relevant to schizophrenia. Decision making deficits that lead to choices resulting in obesity themselves have neurobiological determinants. Simultaneous treatment of cognitive deficits and related deficits in functional skills, ubiquitous determinants of everyday functioning in schizophrenia, and targeted interventions aimed at poor physical health, especially obesity and associated comorbidities, may lead to additive or even interactive gains in everyday functioning in patients with schizophrenia not previously realized with other interventions.