Vegetarianism and veganism compared with mental health and cognitive outcomes: a systematic review and meta-analysis

Impact of Vegan and Vegetarian Diets on Neurological Health: A Critical Review

BACKGROUND/OBJECTIVES

The global shift towards vegan and vegetarian diets has garnered attention for their ethical, environmental, and potential health benefits. These diets are often rich in phytonutrients and antioxidants, which have been associated with lower levels of inflammatory markers, such as C-reactive protein (CRP) and interleukin-6 (IL-6), suggesting a potential protective effect against systemic inflammation and oxidative stress. However, despite these benefits, concerns remain regarding their impact on neurological health due to the possible deficiencies of critical nutrients such as vitamin B12, DHA, EPA, and iron. This review critically evaluates the influence of these dietary patterns on neurological outcomes, emphasizing their nutritional composition, potential deficiencies, and their interplay with inflammation and oxidative stress.

METHODS

A systematic review of the literature published between 2010 and 2023 was conducted, focusing on studies that explore the relationship between vegan and vegetarian diets and neurological health. Key nutrients such as vitamin B12, omega-3 fatty acids, iron, and zinc were analyzed alongside antinutritional factors and their effects on the nervous system.

RESULTS

Evidence suggests that vegan and vegetarian diets, when well planned, can be rich in phytonutrients and antioxidants, which have been associated with lower levels of inflammatory markers, such as C-reactive protein (CRP) and interleukin-6 (IL-6). These findings indicate a potential role in reducing systemic inflammation and oxidative stress, both of which are linked to neurodegenerative diseases. However, deficiencies in critical nutrients such as vitamin B12, DHA, EPA, and iron have been consistently associated with an increased risk of cognitive decline, mood disturbances, and neurodegenerative disorders. Additionally, the presence of antinutritional factors like phytates and oxalates may further impair nutrient absorption, necessitating careful dietary planning and supplementation.

CONCLUSIONS

While plant-based diets provide anti-inflammatory and antioxidant benefits, their neurological implications depend on nutrient adequacy. Proper planning, supplementation, and food preparation techniques are essential to mitigate risks and enhance cognitive health. Further research is needed to explore long-term neurological outcomes and optimize dietary strategies.

Meat Consumption and Depression: An Updated Systematic Review and Meta-Analysis

Background: Several original studies have reported an inconsistent association between low meat consumption (e.g., vegetarian diets) and the risk of depression. The aim of this study was to quantify the relationship between low meat consumption and depression, identifying possible sources of heterogeneity and the potential role of psychosocial variables. Methods: A systematic review and meta-analysis were performed and reported according to PRISMA guidelines through a comprehensive search in Medline, Web of Science, Scopus, and PsychInfo databases from inception to January 2024 (PROSPERO registration ID: CRD42023405426). The exposures analyzed were (1) a meat-free diet and (2) a flexitarian (low-meat) diet. The outcome was depression. The meta-analysis included twenty longitudinal observational studies. Forest plots were designed, and heterogeneity was analyzed through I2 statistic and subgroup analyses. Publication bias was assessed through funnel plots and Egger's test. Results: The pooled overall analysis showed a protective association (HR: 0.74, 95%CI: 0.59-0.89, I2 = 53.9%) between meat-free consumption and depression, which was consistent in the group of highest-quality studies. The main sources of heterogeneity identified were study quality, study design, year and country of publication, gender inequality in the country, and adjustment for certain variables (including social variables). The association between flexitarian diet and depression (HR: 0.90, 95%CI: 0.81-0.99, I2 = 58.9%) was not consistent between subgroups. Conclusions: The results of this meta-analysis show a consistent protective association between meat-free diets and depression and an inconclusive association regarding flexitarian diet. Primary studies analyzing psychosocial variables are needed to explain these results.

Omnivore, vegan and vegetarian diet quality associations with depressive symptoms: A comparative cross-sectional analysis of the Australian Longitudinal Study on Women's Health

BACKGROUND

Depressive symptoms are experienced by >350 million people globally. Research suggests that a diet rich in plant foods could be protective against depressive symptoms, but vegans and vegetarians who eat a predominant plant-based diet are known to have higher depressive symptoms than omnivores.

METHODS

This study aims to explore a secondary analysis of the association between diet quality and depressive symptoms in women born between 1973 and 1978 who follow vegan, vegetarian, and omnivore diets from the Australian Longitudinal Study of Women's Health at baseline (1996) and at three time points (2000, 2003 and 2009).

RESULTS

After controlling for covarying factors, there was a significant association between diet quality and depressive symptoms in both the plant-based and omnivore groups at both time points F(9, 4851) = 106.90, p < .001. There was no significant difference between diet quality and depressive symptoms between diet type.

CONCLUSIONS

Despite diet type (plant-based or omnivore), adhering to a high-quality diet may decrease depressive symptoms and a low-quality diet may increase depressive symptoms in Australian women.

LIMITATIONS

Caution should be exercised when interpreting these results due to the small sample sizes and small resulting coefficients, there is uncertainty that coefficients this small can be associated with any meaningful change in an individual being treated for depressive symptoms in a clinical setting.

Is trauma associated with plant-based diet choice?

Examinations of links between plant-based diets (e.g., vegetarian and vegan diets) and indices of physical and mental health have received increased attention in the scientific literature in recent years. However, there has been little to no published research examining predictors of plant-based diet choice. Researchers have suggested that plant-based diets could be linked to trauma for a variety of reasons, including the idea that trauma can increase the risk for mental illnesses, and plant-based diets may be adopted to self-medicate mental illness and promote recovery. The current study examined the link between trauma across the lifespan and experiences of intimate partner violence (IPV) with adherence to a plant-based diet. Participants were a nationally representative United States sample of 1665 individuals who completed self-report questionnaires. Consistent with hypotheses, bivariate correlations indicated that all measures of trauma were associated with an increased likelihood of being plant-based. Findings from a logistic regression analysis indicated those with a history of IPV were 2.31 times more likely to be plant-based, and those with any experience of trauma more broadly were 1.09 times more likely to be plant-based. These results suggest the importance of considering the role of trauma and victimization when examining links between plant-based diet and other outcomes and point to a number of possible avenues for additional investigation to better understand these associations.

Do conservatives really have an advantage in mental health? An examination of measurement invariance

Many studies have found that conservatives show an advantage in mental health and happiness and various causes of this have been debated (e.g., religiousness, ideology, or genetics). However, not much attention has been given to examining whether this advantage is psychometrically real, or whether it is due to test bias. We analyzed data from two large Finnish surveys of adults (Ns = 848 and 4,978) from Lahtinen (2024), that measured general anxiety and depression symptoms, as well as a new wokeness scale. Using differential item functioning tests, we found no evidence for measurement bias in these scales. The correlation between index scores of wokeness and mental health (internalizing) was -0.36, which increased to -0.41 when measurement error was removed. The association between wokeness and anxiety (r = -0.33, adjusted r = 0.37) was stronger than wokeness and depression (r = 0.20, adjusted r = 0.22).

Effect of Different Dietary Patterns on Patients with Depressive Disorders: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objectives: This study aimed to investigate the effects of different dietary patterns on depressive disorders. Methods: PubMed/MEDLINE, Cochrane CENTRAL, Embase, PsycINFO, Scopus, and ProQuest databases were systematically searched until 30 April 2024 for randomized controlled trials (RCTs) assessing the effects of different dietary patterns on depressive symptoms in adults with depressive disorders. Secondary outcomes included remission rates, quality of life, and safety. Standardized mean difference (SMD) and 95% confidence intervals (CIs) were aggregated using a random-effects model. Study quality was assessed with the Cochrane Risk of Bias (RoB)-2 tool, and certainty of evidence was determined using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. Results: Five RCTs (n = 952) were included, all investigating the Mediterranean diet (MD) in individuals with major depressive disorder or elevated depression levels. The analysis found no significant effect of short-term MD intervention on depression severity compared to active (SMD = -1.25 [95% CI: -5.11 to 2.61]) or passive (SMD = -0.22 [95% CI: -0.74 to 0.29]) controls. There was no effect on quality of life compared to active controls (SMD = 0.71 [95% CI = -3.38 to 4.79]). Intermediate and long-term results were similar. The overall risk of bias was "some concerns", and the certainty of evidence was "very low" for most of the results. Conclusions: The MD appears to have no potential influence on major depressive disorder. However, this finding should be interpreted cautiously due to the limited number of RCTs. Further studies on dietary patterns and depressive disorders are needed for more robust conclusions. Systematic Review Registration: PROSPERO registration no. CRD42024541885.

Assessing the Roles of Retinol, Vitamin K2, Carnitine, and Creatine in Plant-Based Diets: A Narrative Review of Nutritional Adequacy and Health Implications

Plant-based diets are associated with numerous health benefits, including reduced risks of chronic diseases. However, questions persist regarding the implications of lower dietary intakes of certain non-essential nutrients, such as retinol, vitamin K2, carnitine, and creatine, which are primarily found in animal-derived foods. This narrative review evaluates the roles of these nutrients in human physiology and examines whether their absence in plant-based diets is likely to impact health outcomes. Retinol requirements can be met through the consumption of provitamin A carotenoids in plant foods, even in individuals with reduced conversion efficiency. Endogenous synthesis adequately supports physiological needs for vitamin K2, and currently available evidence does not consistently demonstrate that dietary vitamin K2 provides additional benefits for bone or cardiovascular health. Carnitine and creatine levels may differ between individuals following omnivorous and plant-based diets, but these differences do not result in compromised muscle function, cognitive health, or metabolic outcomes. Current evidence does not indicate that the absence of these non-essential nutrients in plant-based diets adversely affects health or confers disadvantages compared to omnivorous diets.

Eating to live well-Or worse? The role of vegan and vegetarian diets in mental health

BACKGROUND

Over the past two decades, there has been an increase in the prevalence of psychological conditions, such as depression, anxiety, disordered eating, and body image disturbances. In concert with this trend, there was a substantial rise in the advocacy and practice of restrictive dietary patterns, such as veganism and vegetarianism. These parallel developments suggest a relation between diet and mental health, but to date, research has failed to offer clear answers on whether these associations are causal, coincidental, or more complex than superficial analyses suggest.

AIM

Given this context, the purpose of this commentary is to offer a consilient perspective on the role of vegan and vegetarian diets in mental health.

METHODS

We performed a broad qualitative synthesis of the current literature on diet and mental health from sociologic and psychologic perspectives.

RESULTS

Several empirically supported hypotheses were presented with equivocal support.

CONCLUSION

The current evidence suggests that if a nutritionally adequate diet is consumed, the avoidance/consumption of meat and other animal foods will have no significant effects on physical and mental health.

Human gut microbiome, diet, and mental disorders

Diet is one of the most important external factor shaping the composition and metabolic activities of the gut microbiome. The gut microbiome plays a crucial role in host health, including immune system development, nutrients metabolism, and the synthesis of bioactive molecules. In addition, the gut microbiome has been described as critical for the development of several mental disorders. Nutritional psychiatry is an emerging field of research that may provide a link between diet, microbial function, and brain health. In this study, we have reviewed the influence of different diet types, such as Western, Mediterranean, vegetarian, and ketogenic, on the gut microbiota composition and function, and their implication in various neuropsychiatric and psychological disorders.

An overview of drivers and emotions of meat consumption

Emotions are present in almost everything we do, including meat procurement, preparation and consumption. This paper examines the main drivers of this consumption, including sensory and hedonic properties, physiological needs, historical reasons and habits, social influence, ethical motives, practical aspects and other determinants, exploring the meat-related emotions as both an outcome of consumption and as consumption drivers. Emotions are affected by multiple factors relating to the context, the information provided, and the type of product. Positive emotions such as pleasure, satisfaction, proudness and joyfulness have been described in relation to meat, as well as some neutral or negative ones. To enhance positive emotions and increase meat liking, it is essential to improve animal welfare and promote a more sustainable production, focusing on nutritional and sensory quality and providing consumers with reliable information.

Effect of Moderate Red Meat Intake Compared With Plant-Based Meat Alternative on Psychological Well-Being: A 10-Wk Cluster Randomized Intervention in Healthy Young Adults

Background

A healthy diet has been proposed to support good mental health, but the addition of either red meat or meat alternatives is nuanced.

Objectives

We aimed to determine if psychological and physiological well-being is differentially affected by consuming recommended weekly amounts of either lean red meat or plant-based meat alternatives (PBMAs) supplemented with a plant-rich diet.

Methods

The trial was a parallel 2-arm randomized intervention of 10 wk duration. Eighty healthy omnivorous young adults were clustered as 40 cohabitating household pairs. Each pair was randomly assigned to consume 3 weekly servings of either fresh New Zealand beef and lamb or the equivalent PBMA. They maintained an otherwise ovo-lacto vegetarian diet, aided by a weekly meal kit and supported by engaged advice from research dietitians. Psychological measures were well-being (World Health Organization-Five Well-Being Index); depression, anxiety, and stress (depression anxiety stress scales-short form-21); and fatigue (multidimensional fatigue symptom inventory-short form) assessed weekly throughout the trial. Blood biomarkers included neurotransmitter-related compounds, iron status and vitamins B12 and D. Physical activity and sleep were estimated by a fitness wristband. Mixed effect modeling evaluated changes in each outcome over time relative to its baseline and compared the 2 interventions accounting for randomization unit clustering.

Results

Thirty-nine household pairs completed the trial. Participants measured as psychologically healthy at baseline. There were no significant differences between groups in the degree of change from baseline for the psychological outcomes, nor for the majority of the circulatory markers. Differences in changes to vitamin B12 status and 3 neurotransmitter-related compounds (adenosine, agmatine, and tyrosine) from baseline to week 10 were observed between groups. Results were similar in all sensitivity analyses when adjusting for physical activity, sleep, and diet quality covariates.

Conclusions

There was no effect on the psychological measures and limited change to physiological status when comparing a balanced diet containing either red meat or PBMAs in healthy young adults.

Associations between eating habits and mental health among adolescents in five nordic countries: a cross-sectional survey

BACKGROUND

The role of eating habits in adolescent mental health has become a growing area of interest for researchers and health professionals. Recent studies suggest that healthy eating habits may play a role in the development and management of mental health. However, existing literature is largely based on clinical populations, and comparisons are challenged by sociocultural differences and methodological issues. The aim of the present study was to use nationally representative data based on standardized procedures, to explore associations between adolescents eating habits and mental health, considering the importance of age, gender, socioeconomic factors, and country.

METHODS

The study was based on data from Nordic adolescents (age 11, 13 and 15 years) who participated in the 2017/2018 Health Behavior in School-aged Children (HBSC) study (n = 22384). General linear modelling and multigroup regression analysis were used to examine the relationship between food habits (intake of fruit, vegetables, sweets, soft drinks), meal habits (intake of breakfast and having family meals together), and mental health (life satisfaction and subjective health complaints). The analyses were weighted and adjusted for age, gender, socio-economic status, and country.

RESULTS

Overall, healthier eating habits were associated with better mental health. The strongest associations were found between meal habits (breakfast consumption and having family meals together) and mental health. Gender and country differences were seen, with weaker associations found among Danish boys.

CONCLUSION

Eating habits should be considered when promoting mental health in the adolescent population. While gender differences and cross-country variations exist, even minor enhancements in eating behaviors could yield meaningful benefits.

Psychosocial profiles influencing healthy dietary behaviors among adolescents in Shandong Province, China: a cross-sectional study

Objectives

We aimed to assess the influence of psychosocial profiles on dietary behaviors among school-aged adolescents in China.

Methods

A cross-sectional study was conducted involving 7,862 adolescents from 100 schools in Shandong, China. Psychosocial profiles and dietary behaviors were assessed using the Junior High School Students' Psychosocial Profiles Questionnaire (JPPQ) and the Chinese Diet Quality Questionnaire (DQQ), respectively. Linear regression models were used to investigate the association between adolescents' psychosocial profiles and dietary behaviors.

Results

The mean age of the participants was 13.18 ± 1.15 years; 48.5% of them were boys. The majority of participants (97.90%) were Han Chinese, and approximately half of the participants (50.90%) resided in rural areas. After adjusting for sociodemographic characteristics and family computer and Internet ownership and usage, healthy dietary behavior was positively correlated with higher psychosocial profile scores (p < 0.05). The stratified analysis results revealed that the group with the highest psychosocial profile score was associated with an increased overall global dietary reference (GDR) score in "households without a family computer and Internet" ( β : 5.357, 95% Cl: 4.931-5.784, p < 0.05).

Conclusion

Good psychosocial profiles exhibit a positive influence on healthy dietary behaviors. Therefore, policymakers should focus on Internet usage to maximize the positive effects on global youth health behaviors.

Chickpea aquafaba: a systematic review of the different processes for obtaining and their nutritional and technological characteristics

Aquafaba is the residual water from cooking chickpea in water. It has a high gelling ability, allowing it to create stable gels. However, those functional properties depend on the legume composition, genotype, cooking time, pressure, and temperature. This study aimed to evaluate the different processes for obtaining aquafaba and compare their nutritional composition and technological characteristics using a systematic review. The authors performed the systematic review by performing specific search strategies for Scopus, Web of Science, Pubmed, Lilacs, Google Scholar, and ProQuest. A total of 17 studies were analyzed. Of them, 17.64% (n = 3) used the wastewater from canned chickpeas, 17.64% (n = 3) compared the wastewater of canned chickpeas and dry grains, and 58.82% (n = 10) used dry chickpeas. Studies used different methods to analyze the protein content. The most used (n = 5) was the Association of Official Analytical Chemists (AOAC). The aquafaba presented carbohydrates at 2.03-2.59 g/100ml; protein at 0.0.8-2.8 g/100ml; and fat at 0.07-0.1 g/100ml. In general, preparing aquafaba followed: soaking (8-10 h at 4 °C-1 chickpea: 4 water), pressure cooking (30 min-2 chickpea: 3 water), and refrigerating (24h/4 °C). In general, the results showed the following steps to prepare aquafaba: soaking for 8-10 h at 4 °C at the proportion of 1:4 (chickpea:water), pressure cooking for 30 min in the proportion of 2:3 (chickpea: water), and refrigerating 24 h/4 °C. These procedures in a homemade aquafaba presented the best results, considering foam development and higher stability. The aquafaba from canned chickpeas has a higher foam-ability and lower emulsion properties than homemade cooking aquafaba.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05920-y.

Gene-vegetarianism interactions in calcium, estimated glomerular filtration rate, and testosterone identified in genome-wide analysis across 30 biomarkers

We examined the associations of vegetarianism with metabolic biomarkers using traditional and genetic epidemiology. First, we addressed inconsistencies in self-reported vegetarianism among UK Biobank participants by utilizing data from two dietary surveys to find a cohort of strict European vegetarians (N = 2,312). Vegetarians were matched 1:4 with nonvegetarians for non-genetic association analyses, revealing significant effects of vegetarianism in 15 of 30 biomarkers. Cholesterol measures plus vitamin D were significantly lower in vegetarians, while triglycerides were higher. A genome-wide association study revealed no genome-wide significant (GWS; 5×10-8) associations with vegetarian behavior. We performed genome-wide gene-vegetarianism interaction analyses for the biomarkers, and detected a GWS interaction impacting calcium at rs72952628 (P = 4.47×10-8). rs72952628 is in MMAA, a B12 metabolic pathway gene; B12 has major deficiency potential in vegetarians. Gene-based interaction tests revealed two significant genes, RNF168 in testosterone (P = 1.45×10-6) and DOCK4 in estimated glomerular filtration rate (eGFR) (P = 6.76×10-7), which have previously been associated with testicular and renal traits, respectively. These nutrigenetic findings indicate genotype can modify the associations between vegetarianism and health outcomes.

Impact of vegetarianism on cognition and neuropsychological status among urban community-dwelling adults in Telangana, South India: a cross-sectional study

PURPOSE

The potential benefits of vegetarian diets in reducing cognitive impairment have garnered attention due to existing mixed results; hence, our study aims to examine the impact of vegetarianism on cognitive function and neuropsychological status among urban community-dwelling adults from Telangana.

METHODS

The dietary patterns were self-reported and dietary data collected using a Food Frequency Questionnaire while cognitive function was assessed using Mini-Mental State Examination (MMSE) and depression, anxiety, and stress (DASS-21) questionnaire for psychological measures. Adults (N = 304) aged 40 years and above, who followed either a vegetarian or non-vegetarian diet for at least 6 months prior to data collection, scored MMSE ≥ 19 indicating mild cognitive impairment, and were recruited using convenience sampling.

RESULTS

Among the participants, vegetarians (n = 155) exhibited significantly better mood states compared to non-vegetarians (n = 149), as indicated by lower scores on the DASS subscales for depression (10.0 ± 0.06 vs. 17.0 ± 0.07, p =  < 0.001), anxiety (4.0 ± 0.05 vs. 6.0 ± 0.07, p = 0.005), and stress (8.0 ± 0.02 vs. 10.0 ± 0.05, p = 0.007). Vegetarians also demonstrated superior cognitive functioning compared to non-vegetarians, as indicated by higher MMSE scores (26.0 ± 0.04 vs. 24.0 ± 0.03, p =  < 0.001). MMSE scores were inversely correlated with depression, anxiety, and stress for vegetarians (ρ = - 0.371, p = 0.000; ρ = - 0.027, p = 0.734; and ρ = - 0.105, p = 0.914), respectively. Similar to the vegetarians group, MMSE scores were negatively correlated with depression (ρ = - 0.059), but the correlation is not significant.

CONCLUSION

Vegetarianism exerted a positive influence on the cognitive and neuropsychological status of the investigated population. Nevertheless, additional research is required to comprehend the underlying mechanisms that elucidate the long-term effects of vegetarianism and plant-based nutritional interventions on brain health.

Depression, Anxiety, Emotional Eating, and Body Mass Index among Self-Reported Vegetarians and Non-Vegetarians: A Cross-Sectional Study in Peruvian Adults

Background: Vegetarianism is commonly associated with various health benefits. However, the association between this dietary regimen and aspects of mental health remains ambiguous. This study compared the symptoms of depression and anxiety, emotional eating (EmE), and body mass index (BMI) in Peruvian vegetarian and non-vegetarian adults. Methods: A cross-sectional study was conducted on 768 Peruvian adults, of whom 284 (37%) were vegetarians and 484 (63%) were non-vegetarians. The Depression Patient Health Questionnaire-2 (PHQ-2), Generalized Anxiety Disorder Scale-2 (GAD-2), and an EmE questionnaire were applied; additionally, the BMI was calculated. Simple and multiple linear regression and Poisson regression models with robust variance were used to evaluate the association between depression, anxiety, EmE, and BMI with dietary patterns. Results: The vegetarians (Adjusted Prevalence Ratio [PR] = 0.24, 95% CI 0.16-0.31; p < 0.001) reported more depressive symptoms than the non-vegetarians. This trend persisted for anxiety, with an adjusted PR of 0.17 (95% CI: 0.01-0.29; p = 0.012). However, the vegetarians (adjusted PR = -0.38, 95% CI: -0.61--0.14; p < 0.001) reported lower EmE scores compared to the non-vegetarians. Likewise, the vegetarians had a lower mean BMI than the non-vegetarians (B = -0.16, 95% CI: -0.21--0.08; p < 0.001). Conclusions: Vegetarian diets are associated with increased symptoms of depression and anxiety, as well as lower EmE and BMI scores. Further longitudinal studies are needed to elucidate these associations and determine causality and the underlying mechanisms involved.

A Narrative Review of the Association Between Healthy Dietary Patterns and Depression

The purpose of the present review is the investigation of healthy dietary patterns and diet quality in relation to depression risk. Nutritional psychiatry is to develop scientifically based research that defines the role of nutrition and nutrients in various aspects of mental health. Growing evidence from the field suggests that diet may play an important role in the prevention and/or treatment of depression. In contrast, there is evidence that unhealthy diets may increase the risk of depression. This emerging research suggests that dietary interventions could help prevent depression or be an alternative or adjunctive therapy for depression. The Mediterranean diet (MedDiet), the Dietary Approaches to Stop Hypertension (DASH) diet, and the vegetarian diet are examined in this review. The electronic databases PubMed, Scopus, and Google Scholar were searched for relevant studies published during the last five years. We found many results that support that healthy eating patterns (high in vegetables, fruits, whole grains, nuts, seeds, and fish, low in processed foods) are related to a reduction in the risk of depression. The most robust findings are related to MedDiet, where we also found several positive results for the DASH diet. Regarding the vegetarian diet, there are inconsistent reports. Furthermore, a consistent finding refers to a lower Dietary Inflammatory Index (DII) as associated with a lower depression risk. It has been observed that people suffering from depression have poorer nutritional quality, with lower fruit and vegetable intake. This observation may strengthen the argument that nutritional interventions should be incorporated as an important "pillar" in the multifactorial treatment of patients. However, more well-designed studies are needed to establish the relationship between dietary patterns and mental health. In particular, interventional, longitudinal studies could be more enlightening.

Motivations matter: moral and health-related motives indirectly relate to differential psychological health indicators among vegetarians

Due to rising popularity of vegetarianism in recent years, research interest has surged in examining the relationship between vegetarianism and psychological health. However, given inconsistent findings in prior research, the answer to whether practicing vegetarianism is associated with better or worse psychological health is still elusive. The present investigation aimed to demonstrate that vegetarians are not homogeneous in terms of psychological experiences, such that it is crucial to consider the motives behind vegetarians' dietary choice when examining their psychological health. In a survey study with 266 vegetarians and 104 omnivores, it was shown that health vegetarians displayed higher levels of disordered eating as compared to moral vegetarians and omnivores. Mediation analyses further revealed that, among vegetarians, health motivation was positively correlated with disordered eating tendencies, indirectly linking it with poorer psychological health; moral motivation was positively correlated with prosocial behavior, which in turn predicted better psychological health. These findings have implications for understanding the psychological health of vegetarians with different dietary motives and for developing interventions to promote their psychological health.

Vitamin B12 deficiency and neuropsychiatric symptoms in Lebanon: A cross-sectional study of vegans, vegetarians, and omnivores

BACKGROUND

Vitamin B12 deficiency is responsible for a variety of complications, particularly neurological/neuropsychiatric complications, including depression, irritability, paresthesia and insomnia. Since vitamin B12 is found in animal-derived products, vegans/vegetarians are at a greater risk for developing vitamin B12 deficiency.

AIMS

This study aims to investigate the occurrence of vitamin B12 deficiency among a sample of adult Lebanese population, with a particular emphasis on assessing the severity of its neurological/neuropsychiatric signs and symptoms, especially among vegans/vegetarians.

METHODOLOGY

A cross-sectional study was conducted among a sample of 483 Lebanese adults. Data was collected through a standardized questionnaire that included socio-demographic characteristics, the Patient Health Questionnaire-9 (PHQ-9), Generalized anxiety disorders-7 (GAD-7), and the Insomnia Severity Index (ISI) scales.

RESULTS

Among the participants, 11.4% were in the vegan/vegetarian group, and about 43.1% had vitamin B12 deficiency. After analyzing the PHQ-9, GAD-7 and ISI total scores, higher scores were reported in participants with vitamin B12 deficiency, compared to individuals with normal vitamin B12 serum levels (p < 0.001). Regarding the diet type, vegans/vegetarians were more susceptible to developing depression compared to omnivores (mean scores of 11.92 vs 8.02 on the PHQ-9 scale, respectively, with p < 0.001). Of the patients with vitamin B12 deficiency, 81.1% reported having paresthesia compared to 43.7% of individuals with no vitamin B12 deficiency (p < 0.001).

CONCLUSION

Vitamin B12 deficiency in Lebanon is notably high and is linked to an increased risk of developing depression, generalized anxiety disorder, insomnia, and paresthesia. Vegans/vegetarians exhibit a higher susceptibility to developing depression compared to omnivores, whereas the risk of developing insomnia, generalized anxiety disorder and paresthesia was statistically insignificant when comparing vegans/vegetarians to omnivores.

Vegetarianism and mental health: Evidence from the 1970 British Cohort Study

BACKGROUND

Reducing animal product consumption has benefits for population health and the environment. The relationship between vegetarianism and mental health, however, remains poorly understood. This study explores this relationship in a nationally representative cohort in Great Britain.

METHODS

We use data from the 1970 British Cohort Study, which collected information on vegetarianism at age 30 in 2000 (n = 11,204) and psychological distress (PD) at ages 26, 30, 34, 42, and 46-48 in 2016/18. We first developed a statistical adjustment strategy by regressing PD at age 30 on vegetarianism and 14 confounders measured at ages 10 and 26. We then ran multilevel growth curve models, testing whether within-person changes in PD between ages 30 and 46-48 differed by vegetarianism, before and after statistical adjustment.

RESULTS

At age 30, 4.5 % of participants reported being vegetarian. In the cross-sectional models at age 30, vegetarians reported more distress compared with non-vegetarians in bivariate analysis (b = 0.30, 95%CI 0.09, 0.52), but this difference disappeared in the fully-adjusted model (b = 0.02, 95%CI -0.17, 0.21). In the longitudinal models between ages 30 and 46/48, there were no differences in within-person changes in psychological distress between vegetarians and non-vegetarians (p = .723). Sensitivity analyses using red meat consumption yielded similar findings.

CONCLUSION

In this British cohort, vegetarianism at age 30 was not associated with changes in psychological distress during mid-adulthood. Since psychological distress in early adulthood predicted vegetarianism at age 30, more studies are needed to disentangle the progression of this relationship over the life-course.

The Role of Gut Microbiota, Nutrition, and Physical Activity in Depression and Obesity-Interdependent Mechanisms/Co-Occurrence

Obesity and depression are interdependent pathological disorders with strong inflammatory effects commonly found worldwide. They determine the health status of the population and cause key problems in terms of morbidity and mortality. The role of gut microbiota and its composition in the treatment of obesity and psychological factors is increasingly emphasized. Published research suggests that prebiotic, probiotic, or symbiotic preparations can effectively intervene in obesity treatment and mood-dysregulation alleviation. Thus, this literature review aims to highlight the role of intestinal microbiota in treating depression and obesity. An additional purpose is to indicate probiotics, including psychobiotics and prebiotics, potentially beneficial in supporting the treatment of these two diseases.

Association of plant-based dietary patterns with depression and anxiety symptoms in Chinese older adults: A nationwide study

BACKGROUND

The associations of plant-based dietary patterns with depression and anxiety symptoms among older adults have not been extensively studied. Therefore, the purpose of this study was to examine these associations in Chinese older adults.

METHODS

Data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) was employed in the present study. The simplified food frequency questionnaire was used to assess the overall plant-based diet index (PDI), healthful plant-based diet index (hPDI), and unhealthful plant-based diet index (uPDI). The Center for Epidemiologic Studies Depression Scale-10 (CES-D-10) was used to evaluate depression symptoms, and the Generalized Anxiety Disorder Scale-7 (GAD-7) was used to assess anxiety symptoms. This study employed logistic regression and linear regression to examine the associations between plant-based dietary patterns and symptoms of depression and anxiety.

RESULTS

This study included 11,971 older adults, with a mean age of 83.23 ± 11.10 years. The results indicated that PDI and hPDI were negative associated with depression symptoms (adjusted β -0.09, 95 % CI -0.11, -0.07) (adjusted β -0.09, 95 % CI -0.11, -0.07) and anxiety symptoms (adjusted β -0.03, 95 % CI -0.04, -0.02) (adjusted β -0.04, 95 % CI -0.05, -0.02), while uPDI was positive associated with depression symptoms (adjusted β 0.09, 95 % CI 0.07, 0.11) and anxiety symptoms (adjusted β 0.04, 95 % CI 0.03, 0.05).

CONCLUSIONS

The findings from this study have the potential to promote healthy dietary patterns in older adults, and may have implications for the prevention and management of depression and anxiety in this population.

Popular Diets and Skin Effects: A Narrative Review

Numerous diets for losing weight, building strength, and managing a range of cardiovascular, neurologic, and skin diseases have become popular in recent years. The ketogenic diet and intermittent fasting in particular have shown promising results in clinical and sports medicine. The Mediterranean diet, in turn, is widely recognized for its numerous health benefits. Also popular are the paleo diet and vegan and gluten-free diets. Positive effects on inflammatory conditions, such as psoriasis, atopic dermatitis, hidradenitis suppurativa, and acne, have been observed in patients who practice intermittent fasting or follow ketogenic or Mediterranean diets. This last choice may also protect against certain skin cancers. We review the role of several popular diets in the management of skin disorders.

[Translated article] Popular Diets and Skin Effects: A Narrative Review

Numerous diets for losing weight, building strength, and managing a range of cardiovascular, neurologic, and skin diseases have become popular in recent years. The ketogenic diet and intermittent fasting in particular have shown promising results in clinical and sports medicine. The Mediterranean diet, in turn, is widely recognized for its numerous health benefits. Also popular are the paleo diet and vegan and gluten-free diets. Positive effects on inflammatory conditions, such as psoriasis, atopic dermatitis, hidradenitis suppurativa, and acne, have been observed in patients who practice intermittent fasting or follow ketogenic or Mediterranean diets. This last choice may also protect against certain skin cancers. We review the role of several popular diets in the management of skin disorders.

Pathogenesis and treatment of depression: Role of diet in prevention and therapy

In recent years, there has been a significant increase in depression, which is related to, among other things, the COVID-19 pandemic. Depression can be fatal if not treated or if treated inappropriately. Depression is the leading cause of suicide attempts. The disease is multifactorial, and pharmacotherapy often fails to bring satisfactory results. Therefore, increasingly more importance is attached to the natural healing substances and nutrients in food, which can significantly affect the therapy process and prevention of depressive disorders. A proper diet is vital to preventing depression and can be a valuable addition to psychological and pharmacologic treatment. An inadequate diet may reduce the effectiveness of antidepressants or increase their side effects, leading to life-threatening symptoms. This study aimed to review the literature on the pathogenesis of the development and treatment of depression, with particular emphasis on dietary supplements and the role of nutrition in the prevention and treatment of depressive disorders.

Veganism and body weight: An N of 1 self-experiment

The causal effect that veganism has on body weight has not been scientifically examined. An N of 1 self-experiment was conducted in which blinded body weight and additional behavioural and psychological measures were assessed during two phases of vegan vs. non-vegan lifestyle adherence. In study phase 1, body weight change was -0.8 kg over 1 month of veganism (vs. +0.5 kg non-vegan month). In study phase 2, weight change was -1.2 kg over two veganism months (vs. +1.6 kg non-vegan months). Behavioural and psychological measures were similar during vegan vs. non-vegan periods. Veganism appeared to reduce body weight in this N of 1 self-experiment.

Diet and Depression during Peri- and Post-Menopause: A Scoping Review Protocol

The aim of the proposed scoping review is to describe and summarize studies assessing the associations between diet-related variables and depression in peri- and post-menopausal women. Studies examining the associations between diet-related variables and mental health indicators in women undergoing menopausal transition or in the post-menopausal period will be systematically retrieved via Medline, EMBASE, PsycINFO, Web of Science, and Scopus databases. All articles identified through the database searches will be imported into Covidence. Following the removal of duplicates, two authors will independently perform title and abstract screening, as well as full-text assessment against eligibility criteria. Data will be extracted using tables developed for observational and experimental studies. The methodological quality of randomized trials, cohort and cross-sectional studies, and case-control studies, will be assessed using the Cochrane risk-of-bias (RoB-2) tool, the NHLBI Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies, and the NHLBI Quality Assessment Tool for Case-Control studies, respectively. Data extraction tables will be used to produce two tables summarizing the main characteristics and findings of the studies included in the review. In the proposed review, we will systematically identify and summarize the currently available evidence on the association between diet-related variables and depression in peri- and post-menopausal women. To our knowledge, this is the first review focusing on this subgroup of the population. Protocol registration: osf.io/b89r6.

Vegetarian and vegan diets: benefits and drawbacks

Plant-based diets have become increasingly popular thanks to their purported health benefits and more recently for their positive environmental impact. Prospective studies suggest that consuming vegetarian diets is associated with a reduced risk of developing cardiovascular disease (CVD), diabetes, hypertension, dementia, and cancer. Data from randomized clinical trials have confirmed a protective effect of vegetarian diets for the prevention of diabetes and reductions in weight, blood pressure, glycosylated haemoglobin and low-density lipoprotein cholesterol, but to date, no data are available for cardiovascular event rates and cognitive impairment, and there are very limited data for cancer. Moreover, not all plant-based foods are equally healthy. Unhealthy vegetarian diets poor in specific nutrients (vitamin B12, iron, zinc, and calcium) and/or rich in highly processed and refined foods increase morbidity and mortality. Further mechanistic studies are desirable to understand whether the advantages of healthy, minimally processed vegetarian diets represent an all-or-nothing phenomenon and whether consuming primarily plant-based diets containing small quantities of animal products (e.g. pesco-vegetarian or Mediterranean diets) has beneficial, detrimental, or neutral effects on cardiometabolic health outcomes. Further, mechanistic studies are warranted to enhance our understanding about healthy plant-based food patterns and the biological mechanisms linking dietary factors, CVD, and other metabolic diseases.

Gathering the Evidence on Diet and Depression: A Protocol for an Umbrella Review and Updated Meta-Analyses

Our objectives are to perform (1) an umbrella review on diet and depression, (2) a systematic review update on dietary patterns and depression, and (3) updated meta-analyses using studies from the previous two objectives. Systematic reviews examining the relationships between diet and depression and primary studies on the relationship between dietary patterns and depression will be systematically retrieved via several databases. All articles identified through the database searches will be imported into Covidence. Following duplicates removal, two authors will independently perform title and abstract screening and full-text assessment against eligibility criteria. Data will be extracted using tables developed for both systematic reviews and primary studies. The methodological quality of systematic reviews will be assessed using the AMSTAR-2 tool. The risk of bias in randomized trials, cohort and cross-sectional studies, as well as case-control studies, will be assessed with the Cochrane risk-of-bias (RoB-2) tool, the NHLBI Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies, and the NHLBI Quality Assessment Tool for Case-Control studies, respectively. For each dietary variable, data extracted will be used to produce: (1) a summary of systematic reviews' characteristics and results table, (2) a summary of the primary studies characteristics table, (3) a qualitative summary of results from the primary studies table, and (4) a quantitative summary of results in the form of forest plots. The certainty of evidence will be assessed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. Upon completion, this systematic review will be the most comprehensive and up-to-date synthesis of currently available evidence on the relationships between diet and depression. It will serve as a key reference to guide future research and as a resource for health professionals in the fields of nutrition and psychiatry. PROSPERO CRD42022343253.

Vegetarians: Past, Present, and Future Regarding Their Diet Quality and Nutritional Status

The term "vegetarian" usually refers to individuals who exclude meat, fish, poultry and/or their derived products from their diet [...].

Brain Injury: How Dietary Patterns Impact Long-Term Outcomes

Purpose of Review

Individuals with a history of traumatic brain injury (TBI) are at a much greater risk for developing cardiovascular disease (CVD) compared to the general population. This review discusses dietary patterns as a means of addressing modifiable risk factors following TBI exposure. Evidence-based resources for practicing Physiatrists and Brain Injury Medicine specialists pertaining to nutrition education and counseling are also provided.

Recent Findings

We examined Mediterranean, Dietary Approaches to Stop Hypertension, plant-based, ketogenic, and intermittent fasting dietary patterns through publications of clinical trials and systematic reviews. While many reviews had significant positive findings, some were limited by generalizability.

Summary

While there is extensive literature on the immediate nutrition goals in the inpatient setting following an acute TBI exposure, there is limited literature discussing the nature of diet and nutrition in the post-acute setting. Fortunately, most individuals with TBI exposure survive their initial injury and continue into the recovery phase. The scientific literature supports increased morbidity and mortality with chronic TBI exposure compared to matched counterparts, most notably with CVD. A diet rich in fiber and nutrients but limited in added sugars, saturated fats, and excess calories would likely have the greatest cardiovascular and related neurologic protection. Future studies are needed to assess the specific impact of dietary interventions in the chronic phase of brain injury recovery.

Changes in Plant-based Dietary Quality and Subsequent Risk of Cognitive Impairment among Older Chinese Adults: A National Community-based Cohort Study

BACKGROUND

It is unclear how changes in plant-based dietary quality are linked to subsequent risk of cognitive impairment. This study aims to evaluate this relationship using data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS).

METHODS

A total of 6662 participants free of cognitive impairment in 2008 were included and followed up to 2018. Plant-based dietary quality was assessed by three indices: overall plant-based diet index (PDI), healthful plant-based diet index (hPDI), and unhealthful plant-based diet index (uPDI). Changes in plant-based diet quality from 2008 to 2011 were classified into quintiles. We assessed incident cognitive impairment (from 2011 to 2018) by using the Mini-Mental State Examination (MMSE). Cox proportional-hazards models were performed.

RESULTS

We recorded 1571 incident cases of cognitive impairment during a median of 10 years of follow-up. Compared with participants whose plant-based diet had no change or was relatively stable over three years, the full-adjusted hazard ratios (HRs) with 95% confidence intervals (CI) for cognitive impairment were 0.77 (0.64, 0.93), 0.72 (0.60, 0.86), and 1.50 (1.27, 1.77) among participants with a large increase in PDI, hPDI, and uPDI, respectively. The HRs with 95% CI were 1.22 (1.02, 1.44), 1.30 (1.11, 1.54), and 0.80 (0.67, 0.96) among participants with a large decrease in PDI, hPDI, and uPDI, respectively. Every 10-point increase in PDI and hPDI was associated with 26% and 30% lower risk of cognitive impairment, while every 10-point increase in uPDI was associated with 36% higher risk.

CONCLUSIONS

Older adults with increased adherence to an overall plant-based diet and a healthful plant-based diet over three years have a lower risk of cognitive impairment, while those with increased adherence to an unhealthy plant-based diet had a higher risk of cognitive impairment.

The importance of vitamin B12 for individuals choosing plant-based diets

Vitamin B₁₂ is an essential nutrient that is not made by plants; consequently, unfortified plant-based foods are not a reliable supply. Recent estimates suggest high rates of vitamin B₁₂ deficiency among the vegetarian and vegan populations, particularly in pregnant women or women of child-bearing age who, for ethical and health reasons, are shifting towards higher consumption of plant-based foods in ever-increasing numbers. Vitamin B₁₂ plays crucial metabolic roles across the life-course and in particular during pregnancy and in early development (first 1000 days of life). Evidence now implicates vitamin B₁₂ deficiency with increased risk to a range of neuro, vascular, immune, and inflammatory disorders. However, the current UK recommended nutrient intake for vitamin B₁₂ does not adequately consider the vitamin B₁₂ deficit for those choosing a plant-based diet, including vegetarianism and in particular veganism, representing a hidden hunger. We provide a cautionary note on the importance of preventing vitamin B₁₂ deficits for those individuals choosing a plant-based diet and the health professionals advising them.

The Association between Vegan, Vegetarian, and Omnivore Diet Quality and Depressive Symptoms in Adults: A Cross-Sectional Study

Dietary patterns and depressive symptoms are associated in cross-sectional and prospective-designed research. However, limited research has considered depression risk related to meat-based and plant-based dietary patterns. This study explores the association between diet quality and depressive symptoms across omnivore, vegan, and vegetarian dietary patterns. A cross-sectional online survey utilised the Dietary Screening Tool (DST) and the Centre for Epidemiological Studies of Depression Scale (CESD-20) to measure diet quality and depressive symptoms, respectively. A total of 496 participants identified as either omnivores (n = 129), vegetarians (n = 151), or vegans (n = 216). ANOVA with Bonferroni post hoc corrections indicates that dietary quality was significantly different between groups F(2, 493) = 23.61, p < 0.001 for omnivores and vegetarians and omnivores and vegans. Diet quality was highest in the vegan sample, followed by vegetarian and omnivore patterns. The results show a significant, moderately negative relationship between higher diet quality and lower depressive symptoms (r = -0.385, p < 0.001) across groups. Hierarchical regression showed that diet quality accounted for 13% of the variability in depressive symptoms for the omnivore sample, 6% for vegetarians, and 8% for vegans. This study suggests that diet quality in a meat-based or plant-based diet could be a modifiable lifestyle factor with the potential to reduce the risk of depressive symptoms. The study indicates a greater protective role of a high-quality plant-based diet and lower depressive symptoms. Further intervention research is needed to understand the bi-directional relationship between diet quality and depressive symptoms across dietary patterns.

Association between dietary patterns and depression: an umbrella review of meta-analyses of observational studies and intervention trials

CONTEXT

Depression is the most common causes of disease burden worldwide (GBD 2017 Disease and Injury Incidence and Prevalence Collaborators. Global, regional, and national incidence, prevalence, and years lived with disability for 354 diseases and injuries for 195 countries and territories, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet. 2018;392:1789-1858).

OBJECTIVE

An umbrella review has been performed to assess the strength and validity of the available observational and trial evidence for the association between a variety of dietary patterns and depression.

DATA SOURCES

MEDLINE/PubMed, Scopus, Web of Science, EMBASE, PsycINFO, and Cochrane Database were searched.

DATA EXTRACTION

The Joanna Briggs Institute Umbrella Review Methodology was used.

DATA ANALYSIS

The review included 19 articles, covering a relatively wide range of dietary patterns: healthy dietary patterns (n = 8), Mediterranean diet (MedDiet) (n = 6), Dietary Inflammatory Index (DII) (n = 5), Western diet (n = 4), Dietary Approaches to Stop Hypertension (DASH) (n = 2), vegetarian diets (n = 4), and other dietary interventions (n = 2). The methodological quality of the included meta-analyses was generally low or critically low. The strength of the evidence was generally weak, although convincing or suggestive evidence was found for an inverse relationship between MedDiet/DII and depression. Higher adherence to the MedDiet and lower DII score were significantly associated with lower risk of depression.

CONCLUSION

Considering the generally high heterogeneity and low quality of the available evidence, further studies adopting more coherent and uniform methodologies are needed.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42020223376.

Mediterranean-Style Diet and Other Determinants of Well-Being in Omnivorous, Vegetarian, and Vegan Women

Due to the lack of studies comparing the determinants of well-being in omnivores and vegetarians, we examined associations of socio-demographic and lifestyle factors, including adherence to a Mediterranean-style diet, in relation to well-being in omnivorous, vegetarian, and vegan women. Well-being was assessed using a validated WHO-5 Well-Being Index. Adherence to the Mediterranean-style diet was determined using a modified Mediterranean diet score. The study was conducted on 636 women (23.9 ± 5.7 years), of whom 47.3% were omnivores, 33.2% vegetarians, and 19.5% vegans. The good well-being group (WHO-5 Index ≥ 13 points) comprised 30.9% of the omnivores, 46.0% of the vegetarians, and 57.3% of the vegans. The remaining participants were classified as belonging to the poor well-being group (<13 points). Compared to the omnivores, the vegetarians and vegans had a 1.6-fold (95% CI: 1.04-2.42) and a 2.4-fold (95% CI: 1.45-3.99) higher probability of having good well-being, respectively. In omnivores, the predictors of good well-being were adherence to the Mediterranean-style diet (a 1-score increment was associated with a 17% higher probability of good well-being, P-trend = 0.016), higher self-perceived health status, and lower levels of stress. In vegetarians and vegans, it was older age, higher physical activity (≥3 h/week), 7-8 h sleep time, and similarly to omnivores' higher self-perceived health status and lower stress level. Our findings indicate that following a Mediterranean-style diet was associated with better well-being in omnivores. Furthermore, we identified that different determinants were associated with well-being in omnivorous and vegetarian and vegan women.

Association between meatless diet and depressive episodes: A cross-sectional analysis of baseline data from the longitudinal study of adult health (ELSA-Brasil)

BACKGROUND

The association between vegetarianism and depression is still unclear. We aimed to investigate the association between a meatless diet and the presence of depressive episodes among adults.

METHODS

A cross-sectional analysis was performed with baseline data from the ELSA-Brasil cohort, which included 14,216 Brazilians aged 35 to 74 years. A meatless diet was defined from in a validated food frequency questionnaire. The Clinical Interview Schedule-Revised (CIS-R) instrument was used to assess depressive episodes. The association between meatless diet and presence of depressive episodes was expressed as a prevalence ratio (PR), determined by Poisson regression adjusted for potentially confounding and/or mediating variables: sociodemographic parameters, smoking, alcohol intake, physical activity, several clinical variables, self-assessed health status, body mass index, micronutrient intake, protein, food processing level, daily energy intake, and changes in diet in the preceding 6 months.

RESULTS

We found a positive association between the prevalence of depressive episodes and a meatless diet. Meat non-consumers experienced approximately twice the frequency of depressive episodes of meat consumers, PRs ranging from 2.05 (95%CI 1.00-4.18) in the crude model to 2.37 (95%CI 1.24-4.51) in the fully adjusted model.

LIMITATIONS

The cross-sectional design precluded the investigation of causal relationships.

CONCLUSIONS

Depressive episodes are more prevalent in individuals who do not eat meat, independently of socioeconomic and lifestyle factors. Nutrient deficiencies do not explain this association. The nature of the association remains unclear, and longitudinal data are needed to clarify causal relationship.

Effect of a Vegan Diet on Alzheimer's Disease

There is evidence indicating that a vegan diet could be beneficial in the prevention of neurodegenerative disorders, including Alzheimer's disease (AD). The purpose of this review is to summarize the current knowledge on the positive and negative aspects of a vegan diet regarding the risk of AD. Regarding AD prevention, a vegan diet includes low levels of saturated fats and cholesterol, contributing to a healthy blood lipid profile. Furthermore, it is rich in phytonutrients, such as vitamins, antioxidants, and dietary fiber, that may help prevent cognitive decline. Moreover, a vegan diet contributes to the assumption of quercetin, a natural inhibitor of monoamine oxidase (MAO), which can contribute to maintaining mental health and reducing AD risk. Nonetheless, the data available do not allow an assessment of whether strict veganism is beneficial for AD prevention compared with vegetarianism or other diets. A vegan diet lacks specific vitamins and micronutrients and may result in nutritional deficiencies. Vegans not supplementing micronutrients are more prone to vitamin B12, vitamin D, and DHA deficiencies, which have been linked to AD. Thus, an evaluation of the net effect of a vegan diet on AD prevention and/or progression should be ascertained by taking into account all the positive and negative effects described here.

Why context matters when changing the diet: A narrative review of placebo, nocebo, and psychosocial context effects and implications for outcome research and nutrition counselling

Placebo (PE) and nocebo effects (NE) have been subjects of systematic research in medicine and psychotherapy for many decades to distinguish between the (specific) pharmacological effect of medication and the (unspecific) effect of the context. Despite this significant research, the awareness, operationalisation, and reflection of the multiplicity of PE, NE, and psychosocial context effects (PSCE) is currently limited when researching outcomes of diet changes in studies without randomisation and placebo control. This neglection is critical as it could systematically influence outcomes by moderating and mediating them and thus reducing the validity and evidence base of these studies. Therefore, we performed a (non-systematic) narrative review (NR) on the following objectives: (1) present a concise overview about the relevance of PE, NE, and PSCE in medicine and nutrition research; (2) review the current state of research on reflecting context effects when studying diet changes; (3) provide useful theoretical foundations via consideration and integration of micro- and macro context effects; (4) operationalise as hypotheses the potential PE, NE, and PSCE which are specific for researching diet changes; and (5) derive their impact for future research as well as for nutrition counselling. The electronic search in this NR for objective (2) identified N = 5 publications and for objective (4) we found N = 61 articles retrieved in the first round of search, additional references were identified by a manual and snowball search among the cited references resulting finally in N = 37. This NR offers a synoptical basis to foster awareness and operationalisation of a variety of PE, NE, and PSCE. Interdisciplinary research teams should monitor these factors using, e.g., qualitative, mixed-method studies, process evaluation, item bank approaches, moderator and mediator analysis that might reveal substantially new insights, and outcomes of relevance to science and nutrition counselling. Nevertheless, the present NR has several limitations, especially as it is non-systematic, because it is a very heterogeneous field of research, in which the topic we are investigating is usually regarded as marginal and subordinate. Therefore, future research should conduct systematic reviews and particularly theory-based primary studies (experimental research) on hypotheses of PE, NE, and PSCE in outcome research in diet changes.

Biological Role of Nutrients, Food and Dietary Patterns in the Prevention and Clinical Management of Major Depressive Disorder

Major Depressive Disorder (MDD) is a growing disabling condition affecting around 280 million people worldwide. This complex entity is the result of the interplay between biological, psychological, and sociocultural factors, and compelling evidence suggests that MDD can be considered a disease that occurs as a consequence of an evolutionary mismatch and unhealthy lifestyle habits. In this context, diet is one of the core pillars of health, influencing multiple biological processes in the brain and the entire body. It seems that there is a bidirectional relationship between MDD and malnutrition, and depressed individuals often lack certain critical nutrients along with an aberrant dietary pattern. Thus, dietary interventions are one of the most promising tools to explore in the field of MDD, as there are a specific group of nutrients (i.e., omega 3, vitamins, polyphenols, and caffeine), foods (fish, nuts, seeds fruits, vegetables, coffee/tea, and fermented products) or dietary supplements (such as S-adenosylmethionine, acetyl carnitine, creatine, amino acids, etc.), which are being currently studied. Likewise, the entire nutritional context and the dietary pattern seem to be another potential area of study, and some strategies such as the Mediterranean diet have demonstrated some relevant benefits in patients with MDD; although, further efforts are still needed. In the present work, we will explore the state-of-the-art diet in the prevention and clinical support of MDD, focusing on the biological properties of its main nutrients, foods, and dietary patterns and their possible implications for these patients.

Role of plant-based diets in promoting health and longevity

Western-style obesity-promoting diets are associated with increased inflammation, higher disease incidence and mortality. In contrast, plant-based diets (PBDs), which incorporate large amounts of vegetables and fruit, legumes, whole grains and only a small amount of meat, are generally associated with better health and lower mortality. This narrative review summarizes the evidence on health and life span in adults adhering to PBDs and discusses the potentially longevity-promoting mechanism of PBDs as well as limitations due to nutrient deficiencies. Epidemiologic studies consistently report lower mortality rates in adults who adhering to PBDs when compared with people whose diet regularly includes meat. PBDs are associated with many health benefits, such as improved metabolic and inflammatory profile. In turn, the incidence of cardiovascular disease is lower in adults consuming PBDs, which contributes to their better health. The health-promoting effects of PBDs are still not entirely clear but most likely multifactorial and include modulation of the gut microbiome. The interest in possible longevity-promoting mechanisms of PBDs has increased in recent years, as many characteristics of PBDs such as protein restriction and restriction of certain amino acids are known to extend the life span. While there is ample evidence from animal studies, large-scale human studies, which also provide insight into the specific mechanisms of the effect of PBDs on longevity, are missing. However, due to the lower protein content of PBDs, there appears to be an age limit for the anticipated health effects, as adults over 65 require larger amounts of protein.

Evidence of a vegan diet for health benefits and risks - an umbrella review of meta-analyses of observational and clinical studies

To summarize and evaluate the evidence on the health impact of a vegan diet, we conducted an umbrella review of systematic reviews and meta-analyses. PubMed, Cochrane Library, Web of Science and Epistemonikos were searched up to September 2021. Meta-analyses were recalculated by using a random effects model. The certainty of evidence (CoE) was evaluated by the GRADE approach. For the general healthy population, a vegan diet was effective for reducing body weight [MD (95% CI): -2.52 kg (-3.06, -1.98), n = 8 RCTs; moderate CoE] and was associated with further health benefits (with low CoE), including a lower risk of cancer incidence [SRR (95% CI): 0.84 (0.75, 0.95), n = 2] and a trend for lower risk of all-cause mortality [SRR (95% CI): 0.87 (0.75, 1.01), n = 2], as well as lower ApoB levels [MD (95% CI): -0.19 µmol/L (-0.23, -0.15), n = 7 RCTs). The findings suggested adverse associations for a vegan diet with risk of fractures [SRR (95% CI): 1.46 (1.03, 2.07), n = 3; low CoE]. For persons with diabetes or at high CVD risk, a vegan diet reduced measures of adiposity, total cholesterol, LDL and improved glycemic control (CoE moderate to low). A vegan diet may have the potential for the prevention of cardiometabolic health, but it may also impair bone health. More well-conducted primary studies are warranted.

Is vegetarianism related to anxiety and depression? A cross-sectional survey in a French sample

OBJECTIVE

The relationship between vegetarianism and mental health is controversial. The aim of the present study is to examine the cross-sectional association between anxiety, depression, and vegetarianism in a French sample while controlling for potential confounders.

DESIGN

Self-reported questionnaire data were obtained from a large cross-sectional sample.

PARTICIPANTS AND SETTING

We included an online sample of 6578 participants aged 18-90, 70.8% females.

RESULTS

Analyses of variance with age, gender, body mass index (BMI), educational level, monthly income, and city size as covariates showed that vegetarians and non-vegetarians did not appear to have significantly different levels of anxiety or depression.

CONCLUSION

Our findings do not suggest a link between plant-based diet and anxiety or depression, either before or after adjustment for relevant factors.

Mechanisms affecting brain remodeling in depression: do all roads lead to impaired fibrinolysis?

Fibrinolysis occurs when plasminogen activators, such as tissue plasminogen activator (tPA), convert plasminogen to plasmin, which dissolves the fibrin clot. The proteolytic activity of tPA and plasmin is not restricted to fibrin degradation. In the extravascular space, these two proteases modify a variety of substrates other than fibrin, playing a crucial role in physiological and pathological tissue remodeling. In the brain, for example, tPA and plasmin mediate the conversion of brain-derived neurotrophic factor precursor (proBDNF) to mature brain-derived neurotrophic factor precursor (BDNF). Thus, the fibrinolytic system influences processes reported to be dysfunctional in depression, including neurogenesis, synaptic plasticity, and reward processing. The hypothesis that decreased fibrinolytic activity is an important element in the pathogenesis of depression is supported by the association between depression and increased levels of plasminogen activator inhibitor (PAI)-1, the main inhibitor of tPA. Also, various biochemical markers of depression induce PAI-1 synthesis, including hypercortisolism, hyperinsulinemia, hyperleptinemia, increased levels of cytokines, and hyperhomocysteinemia. Moreover, hypofibrinolysis provides a link between depression and emotional eating, binge eating, vegetarianism, and veganism. This paper discusses the role of reduced fibrinolytic activity in the bidirectional interplay between depression and its somatic manifestations and complications. It also reviews evidence that abnormal fibrinolysis links heterogeneous conditions associated with treatment-resistant depression. Understanding the role of hypofibrinolysis in depression may open new avenues for its treatment.

Perspective: Striking a Balance between Planetary and Human Health: Is There a Path Forward?

The global adoption of predominantly plant-based sustainable healthy diets will help reduce the risk of obesity- and malnutrition-related non-communicable diseases while protecting the future health of our planet. This review examines the benefits and limitations of different types of plant-based diets in terms of health and nutrition, affordability and accessibility, cultural (ethical and religious) acceptability, and the environment (i.e., the four pillars underlying sustainable healthy diets). Results suggest that, without professional supervision, traditional plant-based diets (vegan, vegetarian and pescatarian diets) can increase the risk of nutritional deficiencies among infants, children/adolescents, adult females, pregnant/lactating women and the elderly. In contrast, flexitarian diets and territorial diversified diets (TDDs, e.g., Mediterranean and New Nordic diets) that include large quantities of plant-sourced foods, low levels of red meat and moderate amounts of poultry, fish, eggs and dairy can meet the energy and nutrition needs of different populations without the need for dietary education or supplementation. Compared to vegan, vegetarian and pescatarian diets, more diverse flexitarian diets and TDDs are associated with reduced volumes of food waste and may be more acceptable and easier to maintain for people who previously followed western diets. Although flexitarian diets and TDDs have a greater impact on the environment than vegan, vegetarian and pescatarian diets, the negative effects are considerably reduced compared to western diets, especially if diets include locally-sourced seasonal foods. Further studies are required to define more precisely optimal sustainable healthy diets for different populations and to ensure that diets are affordable and accessible to people in all countries.

Nutrition, Physical Activity, and Other Lifestyle Factors in the Prevention of Cognitive Decline and Dementia

Multiple factors combined are currently recognized as contributors to cognitive decline. The main independent risk factor for cognitive impairment and dementia is advanced age followed by other determinants such as genetic, socioeconomic, and environmental factors, including nutrition and physical activity. In the next decades, a rise in dementia cases is expected due largely to the aging of the world population. There are no hitherto effective pharmaceutical therapies to treat age-associated cognitive impairment and dementia, which underscores the crucial role of prevention. A relationship among diet, physical activity, and other lifestyle factors with cognitive function has been intensively studied with mounting evidence supporting the role of these determinants in the development of cognitive decline and dementia, which is a chief cause of disability globally. Several dietary patterns, foods, and nutrients have been investigated in this regard, with some encouraging and other disappointing results. This review presents the current evidence for the effects of dietary patterns, dietary components, some supplements, physical activity, sleep patterns, and social engagement on the prevention or delay of the onset of age-related cognitive decline and dementia.