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The effects of multi-nutrient formulas containing a combination of n-3 PUFA and B vitamins on cognition in the older adult: a systematic review and meta-analysis.
Fairbairn, P, Dyall, SC, Tsofliou, F
The British journal of nutrition. 2023;129(3):428-441
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Due to the insidious onset, cognitive impairment often goes unnoticed for several years, with clinical diagnosis being made late into the disease progression. Cognition is critical for functional independence as people age, and intact cognition is vital for humans to communicate effectively. The aims of this study were to (i) investigate whether supplementation with a combination of omega-3 polyunsaturated fatty acids (n-3 PUFA) and B vitamins alone or as part of a multi-nutrient formula can prevent cognitive decline in older adults, and (ii) determine whether the effects of a single nutrient intervention with either n-3 PUFA or B vitamins could be modified by the status of the other nutrient. This study is a systematic review and meta-analysis of fourteen studies of which eleven were randomised controlled trials and the rest were post hoc analysis of randomised controlled trials. Results show a benefit of supplementing with nutrient formulas that contain both n-3 PUFA and B vitamins on global cognition and episodic memory with small to moderate effect sizes. In fact, they can help preserve cognition in the older adults. Authors conclude that more experimental work providing a combination of nutrients including both n-3 PUFA and B vitamins, in healthy older adults or those showing early signs of cognitive decline, is clearly warranted to better explore how nutrition can impact the trajectory of cognition in older adults.
Abstract
There is now evidence to suggest that there may be an interaction between B vitamins and n-3 PUFA, with suggestions that increasing intake of both nutrients simultaneously may benefit cognition in older adults. The aim of this systematic review was to investigate whether supplementation with a combination of n-3 PUFA and B vitamins can prevent cognitive decline in older adults. Randomised controlled trials conducted in older adults that measured cognitive function were retrieved. The included trials provided a combination of n-3 PUFA and B vitamins alone, or in combination with other nutrients. Trials that provided n-3 PUFA alone and also measured B vitamin status or provided B vitamin supplementation alone and measured n-3 PUFA status were also included. The databases searched were The Cochrane Library, EMBASE, CINAHL, Scopus and MEDLINE. A total of 14 papers were included in the analysis (n 4913; age: 60-70 years; follow-up 24 weeks to 4 years). The meta-analysis results found a significant benefit of nutrient formulas, which included both n-3 PUFA and B vitamins alongside other nutrients, v. placebo on global cognition assessed using composite scores from a neuropsychological test battery (G = 0·23, P = 0·002), global cognition using single measures of cognition (G = 0·28, P = 0·004) and episodic memory (G = 0·32, P = 0·001). The results indicate that providing a combination of n-3 PUFA and B vitamins as part of a multi-nutrient formula benefits cognition in older adults v. a placebo, and the potential for an interaction between these key nutrients should be considered in future experimental work.
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A combined DHA-rich fish oil and cocoa flavanols intervention does not improve cognition or brain structure in older adults with memory complaints: results from the CANN randomized, controlled parallel-design study.
Vauzour, D, Scholey, A, White, DJ, Cohen, NJ, Cassidy, A, Gillings, R, Irvine, MA, Kay, CD, Kim, M, King, R, et al
The American journal of clinical nutrition. 2023;118(2):369-381
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At a population level, interventions that delay the onset of dementia by 2 years are predicted to reduce the number of dementia patients by 20%. Prospective cohort studies have consistently reported cognitive and neurophysiological benefits of the fish-derived omega-3 long-chain polyunsaturated fatty acids (PUFAs), EPA, and DHA and plant-derived flavanols (FLAVs). This study hypothesised that 12-month administration of a combination of 500 mg cocoa FLAVs with 1.5g omega-3 long-chain PUFAs would improve cognitive function in a mixed subjective cognitive impairment and mild cognitive impairment cohort. This study is based on the results of the CANN randomised controlled trial. A total of 258 participants were recruited and randomised to control or test intervention. Following baseline measurements, 125 participants were randomised into the active OM3FLAV intervention group and 121 into the control group. Results showed that the 1-year intervention with EPA and DHA and cocoa FLAVs did not improve cognition or protect the brain against atrophy in older adults with evidence of memory deficits. Authors concluded that given the complexity of neuropathological processes underpinning cognitive decline and dementia risk, multidomain, multinutrient, or whole diet approaches may be needed to positively impact the cognitive trajectory in the medium term (months to 3 years).
Abstract
BACKGROUND There is evidence that both omega-3 long-chain polyunsaturated fatty acids (PUFAs) (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) and cocoa flavanols can improve cognitive performance in both healthy individuals and in those with memory complaints. However, their combined effect is unknown. OBJECTIVES To investigate the combined effect of EPA/DHA and cocoa flavanols (OM3FLAV) on cognitive performance and brain structures in older adults with memory complaints. METHODS A randomized placebo-controlled trial of DHA-rich fish oil (providing 1.1 g/d DHA and 0.4 g/d EPA) and a flavanol-rich dark chocolate (providing 500 mg/d flavan-3-ols) was conducted in 259 older adults with either subjective cognitive impairment or mild cognitive impairment. Participants underwent assessment at baseline, 3 mo, and 12 mo. The primary outcome was the number of false-positives on a picture recognition task from the Cognitive Drug Research computerized assessment battery. Secondary outcomes included other cognition and mood outcomes, plasma lipids, brain-derived neurotrophic factor (BDNF), and glucose levels. A subset of 110 participants underwent structural neuroimaging at baseline and at 12 mo. RESULTS 197 participants completed the study. The combined intervention had no significant effect on any cognitive outcomes, with the exception of reaction time variability (P = 0.007), alertness (P < 0.001), and executive function (P < 0.001), with a decline in function observed in the OM3FLAV group (118.6 [SD 25.3] at baseline versus 113.3 [SD 25.4] at 12 mo for executive function) relative to the control, and an associated decrease in cortical volume (P = 0.039). Compared with the control group, OM3FLAV increased plasma HDL, total cholesterol ratio (P < 0.001), and glucose (P = 0.008) and reduced TG concentrations (P < 0.001) by 3 mo, which were sustained to 12 mo, with no effect on BDNF. Changes in plasma EPA and DHA and urinary flavonoid metabolite concentrations confirmed compliance to the intervention. CONCLUSIONS These results suggest that cosupplementation with ω-3 PUFAs and cocoa flavanols for 12 mo does not improve cognitive outcomes in those with cognitive impairment. This trial was registered at clinicaltrials.gov as NCT02525198.
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Impact of α-Linolenic Acid, the Vegetable ω-3 Fatty Acid, on Cardiovascular Disease and Cognition.
Sala-Vila, A, Fleming, J, Kris-Etherton, P, Ros, E
Advances in nutrition (Bethesda, Md.). 2022;13(5):1584-1602
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α-Linolenic acid (ALA) is an omega-3 fatty acid found in seeds and nuts such as flaxseeds, chia seeds, and walnuts and in oils such as canola oil, soybean oil, flaxseed oil and walnut oil. It has been shown to reduce the risk of coronary heart disease and cardiovascular disease. This meta-analysis examined the results of various studies, including epidemiologic studies, randomized controlled trials, and systematic reviews, to evaluate the beneficial effects of ALA in improving cognitive function and reducing the risk of cardiovascular disease and coronary heart disease. The included studies showed a correlation between ALA intake and a decreased risk of cardiovascular disease and coronary heart disease, possibly due to ALA's anti-inflammatory properties, as well as its ability to reduce total cholesterol, LDL cholesterol, triglycerides, and blood pressure. The analysis also found that ALA intake may reduce the risk of type 2 diabetes and cognitive impairment. Healthcare professionals can leverage the findings of this analysis to educate individuals about the benefits of dietary ALA in improving cardiovascular and cognitive outcomes. However, further studies are necessary to establish definitive conclusions and determine therapeutic dosage.
Abstract
Given the evidence of the health benefits of plant-based diets and long-chain n-3 (ω-3) fatty acids, there is keen interest in better understanding the role of α-linolenic acid (ALA), a plant-derived n-3 fatty acid, on cardiometabolic diseases and cognition. There is increasing evidence for ALA largely based on its major food sources (i.e., walnuts and flaxseed); however, this lags behind our understanding of long-chain n-3 fatty acids. Meta-analyses of observational studies have shown that increasing dietary ALA is associated with a 10% lower risk of total cardiovascular disease and a 20% reduced risk of fatal coronary heart disease. Three randomized controlled trials (RCTs) [AlphaOmega trial, Prevención con Dieta Mediterránea (PREDIMED) trial, and Lyon Diet Heart Study] all showed benefits of diets high in ALA on cardiovascular-related outcomes, but the AlphaOmega trial, designed to specifically evaluate ALA effects, only showed a trend for benefit. RCTs have shown that dietary ALA reduced total cholesterol, LDL cholesterol, triglycerides, and blood pressure, and epidemiologic studies and some trials also have shown an anti-inflammatory effect of ALA, which collectively account for, in part, the cardiovascular benefits of ALA. A meta-analysis reported a trend toward diabetes risk reduction with both dietary and biomarker ALA. For metabolic syndrome and obesity, the evidence for ALA benefits is inconclusive. The role of ALA in cognition is in the early stages but shows promising evidence of counteracting cognitive impairment. Much has been learned about the health benefits of ALA and with additional research we will be better positioned to make strong evidence-based dietary recommendations for the reduction of many chronic diseases.
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Impulsiveness in children with attention-deficit/hyperactivity disorder after an 8-week intervention with the Mediterranean diet and/or omega-3 fatty acids: a randomised clinical trial.
San Mauro Martin, I, Sanz Rojo, S, González Cosano, L, Conty de la Campa, R, Garicano Vilar, E, Blumenfeld Olivares, JA
Neurologia. 2022;37(7):513-523
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From a clinical perspective, impulsiveness is an important diagnostic characteristic of several psychiatric disorders, including attention-deficit/hyperactivity disorder (ADHD). ADHD is a neurodevelopmental disorder characterised by a persistent pattern of lack of attention and/or hyperactivity and impulsiveness. Dietary approaches to the treatment of ADHD include fatty acid supplementation, particularly with omega-3 polyunsaturated fatty acids (n-3 PUFA) The aim of this study was to analyse changes in the Barratt Impulsiveness Scale (BIS-11c) scores in children with ADHD after an 8-week intervention with the Mediterranean diet, omega-3 fatty acid supplementation, or Mediterranean diet plus omega-3 fatty acid supplementation, as compared to a control group. This study is a cross-sectional, observational cohort study of an 8-week dietary intervention in children with ADHD. Participants (n= 60) were divided into 4 groups, with a control group and 3 intervention groups. Results show that participants with ADHD taking n-3 PUFA supplements (550 mg EPA and 225 mg DHA daily) showed significantly lower levels of impulsiveness than those adopting a Mediterranean diet and controls. These participants also scored lower on all subscales of the BIS (cognitive, motor, and lack of planning). However, there weren’t any differences in impulsive behaviour between patients taking n-3 PUFA supplements and those taking supplements and adhering to the Mediterranean diet. Authors conclude that omega-3 rich (EPA/DHA) supplements should be considered for paediatric patients with ADHD, particularly those with the predominantly hyperactive-impulsive subtype.
Expert Review
Conflicts of interest:
None
Take Home Message:
- The results from this study show no statistically significant differences between groups, except for the group of children receiving omega-3 supplementation.
- Patients with ADHD receiving omega 3 fatty acids (550 mg eicosatetraenoic acid [EPA] and 225 mg docosahexaenoic acid [DHA]) daily presented with less impulsive behaviour than controls with ADHD and patients who adopted a Mediterranean diet.
- EPA/DHA supplements may be considered for paediatric patients with ADHD, particularly those with the predominantly hyperactive-impulsive subtype.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
A randomized, cross-sectional study was conducted to investigate the effects of a Mediterranean diet and Omega-3 supplementation on the impulsiveness in children with attention-deficit/hyperactivity disorder (ADHD).
Methods
76 Children ages 6-16 years of either sex, with a diagnosis of ADHD, were divided into 4 groups, with a control group and 3 intervention groups. Group 1 (controls) followed their usual diet. Group 2 (Mediterranean diet) adopted a Mediterranean diet according to a series of recommendations. Group 3 (omega-3) received omega-3 fatty acid supplements. Group 4 (Mediterranean diet + omega-3) adopted the same diet as group 2 and also received omega 3 fatty acid supplements.
Dieticians provided a tailored Mediterranean diet for each participant. The Omega-3 supplement comprised of 550mg EPA and 225mg of DHA sourced from deep-sea sardines and anchovies.
The Barratt Impulsiveness Scale (BIS-11c) was administered to every child individually to evaluate impulsiveness. The KIDMED questionnaire was administered to evaluate the participant’s adherence to the Mediterranean diet. The study was conducted over 8 weeks. At the endpoint, 60/76 subjects completed the study.
Results
Primary clinical outcomes were:
- Children in the omega-3 supplement group showed a significant drop in the Barratt Impulsiveness Scale score after the intervention (from 49 to 45.10; p =.049).
- Children in the Mediterranean diet and supplement group showed higher cognitive scores (from 2.758 to 2.631).
Limitation
There was a statistically significant difference between groups for the KIDMED score (a measure of adherence to a Mediterranean diet), reflecting a higher adherence to the Mediterranean diet by the control group.
Clinical practice applications:
- Approximately 20%-40% of patients with ADHD do not respond to pharmacological treatment therefore there is a need for alternative options.
- Based on these findings, a practitioner could therefore consider recommending 550mg of eicosatetraenoic acid (EPA) and 225mg of docosahexaenoic acid (DHA) sourced from deep-sea sardines and anchovies for at least 8 weeks to help reduce impulsiveness and improve cognitive function in patients with a hyperactive-impulsive subtype of ADHD.
Considerations for future research:
- This study included combined types of ADHD therefore further investigations are needed on each type of ADHD using different interventions to establish which intervention works best.
- Assessment of diet and omega status before intervention was not conducted, which may have affected outcomes in this study. Further research could consider gathering this data at baseline.
- Larger studies are also needed to determine the relationship between BIS scores and treatments to deepen our understanding of this topic.
- Conflict of interest statement: This study was fully funded by the manufacturer of the provided Omega 3 supplement.
Abstract
INTRODUCTION The Barratt Impulsiveness Scale (BIS) is a self-administered instrument designed to assess the personality/behavioural construct of impulsiveness. Impulsiveness has been associated with several psychiatric disorders, including attention-deficit/hyperactivity disorder (ADHD). This study assesses the progression of impulsive behaviour in children with ADHD after an 8-week dietary intervention with the Mediterranean diet and/or omega-3 fatty acid supplementation, by using a version of the 11-item BIS adapted for children (BIS-11c). METHODS This cross-sectional study includes 60 children with ADHD from the region of Madrid, Spain. Participants were divided into 4 groups, with one control group and 3 intervention groups (Mediterranean diet; omega-3 supplementation; and Mediterranean diet plus omega-3 supplementation). A personalised Mediterranean diet was designed for members of groups 2 and 4. The BIS-11c was administered to determine the level of impulsiveness, and the KIDMED test was used to assess adherence to the Mediterranean diet. RESULTS The supplementation group showed a fairly significant decrease in the total BIS-11c (P = .049). Total cognitive score slightly decreased in the diet and supplementation groups. Only the control group showed a considerable decrease in the total motor score. Total nonplanning scores were lower in all groups after the intervention. Baseline and final BIS-11c scores were positively correlated with treatments (r > 0.9). CONCLUSION An intake of 550 mg EPA fatty acid and 225 mg DHA fatty acid per day for 8 weeks is associated with less marked impulsive behaviour in children with ADHD. A Mediterranean diet may improve BIS scores, although our results are not conclusive in this population.
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Blood levels of circulating methionine components in Alzheimer's disease and mild cognitive impairment: A systematic review and meta-analysis.
Zhao, Y, Dong, X, Chen, B, Zhang, Y, Meng, S, Guo, F, Guo, X, Zhu, J, Wang, H, Cui, H, et al
Frontiers in aging neuroscience. 2022;14:934070
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Alzheimer’s disease (AD) is a chronic neurodegenerative disease that is characterized by progressive memory loss and cognitive deficits. Mild cognitive impairment (MCI) is a prodromal form of AD that is characterised by neurocognitive dysfunction. However, pathological changes associated with AD begin to occur in the brain at least 10 years before the onset of overt symptoms and clinical manifestations, making the discovery of early diagnostic methods and timely interventions important for AD management. The aim of this study was to determine the relationship between circulating methionine (Met) components and AD/MCI. This study is a systematic review and meta-analysis of thirty studies (10 case– control studies, 10 cohort studies, and 10 cross-sectional studies). Results show that: - individuals with AD compared with controls had significantly increased levels of homocysteine. - for people with MCI, there was no significant difference in blood homocysteine levels in the control group. - there were no differences in blood vitamin B12 levels between patients with AD or MCI and controls. Authors conclude that circulating Met components affect patients with AD compared to cognitively normal individuals, with patients exhibiting higher blood homocysteine levels. Additionally, high Met and S-adenosylmethionine levels are risk factors for AD, which supports the association between Met cycle components and AD/MCI.
Abstract
BACKGROUND Circulating methionine components have been reported to be associated with Alzheimer's disease (AD) and mild cognitive impairment (MCI), although outcomes are not always consistent. MATERIALS AND METHODS Database searching was conducted using PubMed, Embase, Cochrane Library, and Web of Science from inception to 26 December 2021. In this study, two reviewers independently identified eligible articles and extracted the data. We used Joanna Briggs Institute (JBI) Critical Appraisal tools to assess the overall quality of the included studies. STATA software was employed to perform meta-analysis evaluating the standardized mean difference (SMD) with its 95% confidence intervals (CIs) using random-effects models. Evidence quality was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria. RESULTS Totally, 30 observational studies were eligible for inclusion. Compared with cognitively normal controls, patients with AD had increased homocysteine (Hcy) levels in the blood [standardized mean difference (SMD) = 0.59, 95% confidence interval [CI]: 0.36-0.82, P = 0.000], plasma (SMD = 0.39, 95% CI: 0.23-0.55, P = 0.000), and serum (SMD = 1.56, 95% CI: 0.59-2.95, P = 0.002). Patients with MCI were not significantly different from controls (SMD = 0.26, 95% CI: -0.07-0.58, P = 0.127). Patients with AD or MCI did not significantly differ from controls of blood vitamin B12 levels, AD (SMD = -0.05, 95% CI: -0.19-0.08, P = 0.440), or MCI (SMD = 0.01, 95% CI: -0.16-0.17, P = 0.94). Some cohort studies have suggested that higher Hcy, methionine, and S-adenosylmethionine levels may accelerate cognitive decline in patients with MCI or AD, and vitamin B12 deficiency is a risk factor for the disease; however, the results of other studies were inconsistent. According to the GRADE system, all these outcomes scored very low to low quality, and no high-quality evidence was found. CONCLUSION Only Hcy levels in the plasma and serum were found to be inversely related to the risk of AD. However, due to the low quality of supporting these results, high-quality studies are needed to verify these findings. SYSTEMATIC REVIEW REGISTRATION http://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022308961.
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Nutritional intervention for diabetes mellitus with Alzheimer's disease.
Li, Z, Li, S, Xiao, Y, Zhong, T, Yu, X, Wang, L
Frontiers in nutrition. 2022;9:1046726
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Diabetes Mellitus (DM) affects more than 463 million people worldwide. Similarly, the number of deaths related to Alzheimer’s disease (AD) has increased by 145%. There are several common risk factors for Type 2 Diabetes and AD, including obesity, insulin resistance, and ageing, as well as common pathological mechanisms, including altered insulin signalling, oxidative stress, neuroinflammation, mitochondrial dysfunction, formation of glycated proteins and metabolic syndrome. This review aims to summarize the therapeutic effects of different nutritional therapy strategies on the reduction of DM and AD risk. Controlling blood sugar levels and reducing calorie intake is crucial to preventing diabetes and Alzheimer's disease. The low-carbohydrate, ketogenic, and Mediterranean diets have been found to improve glucose control in people with Type 2 diabetes (T2D). In addition, MIND (Mediterranean-DASH Diet Intervention for Neurodegenerative Delay) and a ketogenic diet may improve cognition in AD patients. Lactobacillus, Bifidobacterium probiotics, and prebiotics, such as inulin, may inhibit the progression of T2D and AD diseases by suppressing inflammation and modulating gut microbes. In addition, vitamins A, C, D, E, B6, B12, folate, long-chain polyunsaturated fatty acids, zinc, magnesium, and polyphenols may improve cognitive decline, homocysteine levels, and insulin resistance in AD and T2D patients. Healthcare professionals can use the results of this review to understand the beneficial effects of dietary strategies and multi-nutrient supplementation on DM and AD. However, further robust studies are required to investigate the risk factors and underlying mechanisms behind DM-combined AD progression.
Abstract
The combined disease burden of diabetes mellitus (DM) and Alzheimer's disease (AD) is increasing, and the two diseases share some common pathological changes. However, the pharmacotherapeutic approach to this clinical complexity is limited to symptomatic rather than disease-arresting, with the possible exception of metformin. Whether nutritional intervention might extend or synergize with these effects of metformin is of interest. In particular, dietary patterns with an emphasis on dietary diversity shown to affect cognitive function are of growing interest in a range of food cultural settings. This paper presents the association between diabetes and AD. In addition, the cross-cultural nutritional intervention programs with the potential to mitigate both insulin resistance (IR) and hyperglycemia, together with cognitive impairment are also reviewed. Both dietary patterns and nutritional supplementation showed the effects of improving glycemic control and reducing cognitive decline in diabetes associated with AD, but the intervention specificity remained controversial. Multi-nutrient supplements combined with diverse diets may have preventive and therapeutic potential for DM combined with AD, at least as related to the B vitamin group and folate-dependent homocysteine (Hcy). The nutritional intervention has promise in the prevention and management of DM and AD comorbidities, and more clinical studies would be of nutritional scientific merit.
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Plant-based dietary quality and depressive symptoms in Australian vegans and vegetarians: a cross-sectional study.
Lee, MF, Eather, R, Best, T
BMJ nutrition, prevention & health. 2021;4(2):479-486
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Poor diet and mood disorders are known leading causes of morbidity and mortality. Some studies suggest that plant-based diets are associated with improved mood and mental health. The aim of this study was to explore the association between vegan and vegetarian dietary patterns and depressive symptoms in adults by exploring the overall dietary quality of these patterns. This study is an online cross-sectional study which invited vegan and vegetarian adults aged between 18 and 44 years who live in Australia to complete an online survey through social media platforms. Results show that high plant-based diets quality was associated with decreased risk of depressive symptoms. However, this study also shows that following a plant-based diet does not necessarily mean the individual consumes a ‘healthy’ dietary pattern. Authors conclude that further studies are needed which should focus on the specific quality of vegan and vegetarian diets in relation to depression and mental well-being.
Abstract
Plant-based dietary patterns (vegan and vegetarian) are often considered 'healthy' and have been associated with broad health benefits, including decreased risk of obesity and ill health (cardiovascular disease, blood glucose and type II diabetes). However, the association between plant-based diets and mood disorders such as depression remains largely equivocal. This cross-sectional study of 219 adults aged 18-44 (M=31.22, SD=7.40) explored the associations between an estimate of overall plant-based diet quality and depression in vegans (n=165) and vegetarians (n=54). Overall plant-based diet quality was associated with depressive symptoms in vegans and vegetarians F(1, 215)=13.71, p<0.001 accounting for 6% of the variation in depressive symptoms. For those without depression, higher diet quality was protective against depressive symptoms F(1, 125)=6.49, p=0.012. Conversely, for those with depression no association with diet quality was found F(1, 89)=0.01, p=0.963. These findings suggest that a high-quality plant-based diet may be protective against depressive symptoms in vegans and vegetarians. In line with emerging research between food and mental health, higher-quality dietary patterns are associated with a reduced risk of depressive symptoms. Given the rapidly increasing rate of vegan and vegetarian food products within Australia, understanding the potential mechanisms of effects through which a plant-based diet may influence depressive symptoms is required.
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Nutrition to Prevent or Treat Cognitive Impairment in Older Adults: A GRADE Recommendation.
Buckinx, F, Aubertin-Leheudre, M
The journal of prevention of Alzheimer's disease. 2021;8(1):110-116
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Cognitive impairment is a public health problem due to its increasing prevalence in the aging population. Despite pharmacological advances, there are not yet effective treatments to delay or reverse cognitive impairment. Moreover, there is limited knowledge of Alzheimer disease modifiable risk factors namely nutrition. The aim of this review was to grade, classify and provide recommendations for the preferred diet to prevent or to treat cognitive impairment. This review shows that: - some nutritional factors appear to either increase the risk of cognitive decline or protect against it. - risk could be conferred by diets high in milk and dairy products whereas some protection can be offered by adhering to a Mediterranean diet to decrease the risk of cognitive decline. - it is important to follow a diet rich in mono- and poly- unsaturated fatty acids, fruit and vegetable, vitamin D and low in saturated fatty acids. Authors conclude that diet is an important modifiable factor to prevent or protect against cognitive decline.
Abstract
Aging is associated with cognitive declines leading to mild cognitive impairments or Alzheimer disease. Nutrition appear to protect from aging. Some dietary factors could either increase or protect against cognitive declines. This article aimed to provide GRADE recommendations related to nutrition aspects able to prevent or to treat cognitive impairments. A comprehensive literature review was performed using Medline database. The GRADE approach was used to classify quality of the existing evidence (systematic review or meta-analysis).The GRADE process led us to formulate seven key nutritional recommendations to manage cognitive declines, but did not allow us to do it for protein, vitamin B or antioxidants. Thus, 1) adherence to a Mediterranean diet (GRADE 1B); 2) high-level of consumption of mono- or poly- unsaturated fatty acids combined to a low consumption of saturated fatty acids (GRADE 1B); 3) high consumption of fruits and vegetables (GRADE 1B); 4) higher vitamin D intake (GRADE 1C) than the recommended daily allowance. In addition, a ketogenic diet, a low consumption of whole-fat dairy products or a caloric restriction are promising nutritional habits although the evidence does not yet support widespread uptake (GRADE 2C). In conclusion, nutrition is an important modifiable factor to prevent or protect against cognitive decline. Nevertheless, more studies are required to determine specific guidelines such as duration and amounts of nutrients to help older adult to maintain a healthy cognitive life.
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Bacterial Metabolites of Human Gut Microbiota Correlating with Depression.
Averina, OV, Zorkina, YA, Yunes, RA, Kovtun, AS, Ushakova, VM, Morozova, AY, Kostyuk, GP, Danilenko, VN, Chekhonin, VP
International journal of molecular sciences. 2020;21(23)
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Depression is multifactorial disease and it is the most common type of psychiatric disorder. Literature indicates that there are significant differences between the gut microbiota (GM) of patients with depression and healthy controls. The aim of this review was to examine (a) various low-molecular compounds as potential biomarkers of depression in correlation with the metabolism of the GM, and (b) ways to correct the microbiota imbalance. Results show that: - the use of the GM biomarkers, reflecting the neuromodulatory [the process by which nervous activity is regulated through classes of neurotransmitters], immunomodulatory [the process by which the body’s immune system is altered] and antioxidant statuses of the host organism, in the analysis of metagenomic [the study of a collection of genetic material (genomes) from a mixed community of organisms] data from patients with neuropsychiatric diseases, is gaining currency. - diet remains one of the most effective measures that can be taken to restore the microbial balance in the gut and alleviate the symptoms of depression. - a healthy diet during the depression therapy, along with the application of probiotics and psychobiotics, may potentially improve the course of the disease and contribute to the progress of treatment. Authors conclude that further progress in the practical understanding of the role of the GM in depression will greatly depend on correct planning of future metagenomic studies.
Abstract
Depression is a global threat to mental health that affects around 264 million people worldwide. Despite the considerable evolution in our understanding of the pathophysiology of depression, no reliable biomarkers that have contributed to objective diagnoses and clinical therapy currently exist. The discovery of the microbiota-gut-brain axis induced scientists to study the role of gut microbiota (GM) in the pathogenesis of depression. Over the last decade, many of studies were conducted in this field. The productions of metabolites and compounds with neuroactive and immunomodulatory properties among mechanisms such as the mediating effects of the GM on the brain, have been identified. This comprehensive review was focused on low molecular weight compounds implicated in depression as potential products of the GM. The other possible mechanisms of GM involvement in depression were presented, as well as changes in the composition of the microbiota of patients with depression. In conclusion, the therapeutic potential of functional foods and psychobiotics in relieving depression were considered. The described biomarkers associated with GM could potentially enhance the diagnostic criteria for depressive disorders in clinical practice and represent a potential future diagnostic tool based on metagenomic technologies for assessing the development of depressive disorders.
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A Mediterranean Diet with Fresh, Lean Pork Improves Processing Speed and Mood: Cognitive Findings from the MedPork Randomised Controlled Trial.
Wade, AT, Davis, CR, Dyer, KA, Hodgson, JM, Woodman, RJ, Keage, HAD, Murphy, KJ
Nutrients. 2019;11(7)
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Dementia is characterised by severe cognitive impairment and reduced quality of life. Observational studies have demonstrated that populations following a traditional Mediterranean diet experience less cognitive decline and a lowered risk of dementia. The aim of this study was to examine a Mediterranean diet modified to include 2–3 fresh servings of pork each week across measures of cognitive function and well-being. The study is a 24-week parallel randomised controlled crossover design to compare a Mediterranean diet with 2-3 weekly servings of fresh, lean pork (MedPork) and a low-fat control diet (LF). It recruited adults aged 45–80 years due to their increased risk of developing cardiovascular disease. Results indicate that compared with the LF control diet, the MedPork intervention led to higher performance in the cognitive domain of processing speed and higher scores for the SF-36 subscale emotional role functioning. No significant differences were observed for other domains of cognitive function, nor for additional measures of psychological well-being. Authors conclude that the MedPork intervention can improve processing speed and mood in a population at risk of cardiovascular disease and therefore dementia.
Abstract
BACKGROUND The Mediterranean diet may be capable of improving cognitive function. However, the red meat restrictions of the diet could impact long-term adherence in Western populations. The current study therefore examined the cognitive effects of a Mediterranean diet with additional red meat. METHODS A 24-week parallel crossover design compared a Mediterranean diet with 2-3 weekly servings of fresh, lean pork (MedPork) and a low-fat (LF) control diet. Thirty-five participants aged between 45 and 80 years and at risk of cardiovascular disease followed each intervention for 8 weeks, separated by an 8-week washout period. Cognitive function was assessed using the Cambridge Neuropsychological Test Automated Battery. Psychological well-being was measured through the SF-36 Health Survey and mood was measured using the Profile of Mood States (POMS). RESULTS During the MedPork intervention, participants consumed an average of 3 weekly servings of fresh pork. Compared to LF, the MedPork intervention led to higher processing speed performance (p = 0.01) and emotional role functioning (p = 0.03). No other significant differences were observed between diets. CONCLUSION Our findings indicate that a Mediterranean diet inclusive of fresh, lean pork can be adhered to by an older non-Mediterranean population while leading to positive cognitive outcomes.