Adherence to the vegetarian diet may increase the risk of depression: a systematic review and meta-analysis of observational studies

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.

Association between 29 food groups of diet quality questionnaire and perceived stress in Chinese adults: a prospective study from China health and nutrition survey

PURPOSE

Diet plays a fundamental role in promoting resilience against stress-related disorders. We aimed to examine the overall and sex-specific association between food groups and perceived stress in adults.

METHODS

We analyzed the prospective data of 7,434 adults who completed both the 2011 and 2015 surveys of the China Health and Nutrition Survey (CHNS). The Diet Quality Questionnaire (DQQ) was used to code all the food items of 2011 dietary intake into 29 food groups, and perceived stress in 2015 was measured using a 14-item perceived stress scale (PSS-14). Univariate analysis and logistic regression models were used to examine the relationship between food groups and perceived stress.

RESULTS

People who perceived a higher level of stress (PSS-14 total score > 25) made up 41.5% and 45.1% of the male and female groups, respectively (χ2 = 9.605, p = 0.002). Individuals with increased intake of food groups such as legumes, other vegetables, other fruits, yogurt, poultry, fish & seafood, fluid milk, and fruit juice were less likely to experience a higher level of psychological stress (OR range: 0.544-0.892, p < 0.05). Additionally, we found sex-specific associations between food groups and perceived stress. The difference in the proportion of food groups, such as fluid milk and fish & seafood, between the two stress groups in men was statistically significant (p < 0.025). In the female group, the distribution of eight food groups, like legumes and nuts & seeds, between the two stress groups was statistically significant (p < 0.025).

CONCLUSION

This study indicated that food groups were differentially associated with perceived stress.

The associations between plant-based dietary indices with depression and quality of life and insomnia among Iranian adolescent girls in 2015

Although previous research has explored the link between plant-based diets and mental health outcomes, there has been limited study on the quality levels of plant foods in this context. This study was conducted on 733 adolescent girls from cities in northeastern Iran. The validated Iranian version of the Insomnia Severity Index, SF-12v2 questionnaire and Persian version of the Beck Depression Inventory used to assess insomnia and poor quality of life (QoL) and depression, respectively. Dietary intakes assessed using a valid and reliable food frequency questionnaire. The association of scores of plant based dietary index (PDI) and poor QoL, depression and insomnia explored by binary logistic regression. The unadjusted model showed subjects in the highest quartile of healthy PDI had lower chances of insomnia than those in the lowest quartile (OR: 0.50; 95% CI 0.27-0.91, P = 0.024). The association persisted across various adjusted models. Subjects in the highest quartile of unhealthy PDI (uPDI) had higher chances of depression than those in the lowest quartile (OR: 1.83; 95% CI 1.09-3.08, P = 0.022). The significance of the association was maintained after adjusting for other confounders. A healthy plant-based dietary index is associated with a lower odds of insomnia. An unhealthy plant-based dietary index was associated to an increased chance of depression. Findings need to be confirmed by future studies.

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.

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.

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.

The relationship between a plant-based diet and mental health: Evidence from a cross-sectional multicentric community trial (LIPOKAP study)

BACKGROUND

Dietary patterns emphasizing plant foods might be neuroprotective and exert health benefits on mental health. However, there is a paucity of evidence on the association between a plant-based dietary index and mental health measures.

OBJECTIVE

This study sought to examine the association between plant-based dietary indices, depression and anxiety in a large multicentric sample of Iranian adults.

METHODS

This cross-sectional study was performed in a sample of 2,033 participants. A validated food frequency questionnaire was used to evaluate dietary intakes of participants. Three versions of PDI including an overall PDI, a healthy PDI (hPDI), and an unhealthy PDI (uPDI) were created. The presence of anxiety and depression was examined via a validated Iranian version of the Hospital Anxiety and Depression Scale (HADS).

RESULTS

PDI and hPDI were not associated to depression and anxiety after adjustment for potential covariates (age, sex, energy, marital status, physical activity level and smoking). However, in the crude model, the highest consumption of uPDI approximately doubled the risk of depression (OR= 2.07, 95% CI: 1.49, 2.87; P<0.0001) and increased the risk of anxiety by almost 50% (OR= 1.56, 95% CI: 1.14, 2.14; P= 0.001). Adjustment for potential confounders just slightly changed the associations (OR for depression in the fourth quartile= 1.96; 95% CI: 1.34, 2.85, and OR for anxiety in the fourth quartile= 1.53; 95% CI: 1.07, 2.19).

CONCLUSIONS

An unhealthy plant-based dietary index is associated with a higher risk of depression and anxiety, while plant-based dietary index and healthy plant-based dietary index were not associated to depression and anxiety.

Association of omega-6 polyunsaturated fatty acids with blood pressure: A systematic review and meta-analysis of observational studies

OBJECTIVES

This systematic review and meta-analysis aimed at summarizing earlier findings on the association of n-6 PUFAs levels in diets or blood with blood pressure.

METHODS

PubMed/Medline, Scopus, and Web of Science were searched for observational studies. Publications with data on the risk of hypertension, or the correlation between n-6 PUFAs or mean values of serum n-6 PUFAs levels in normotensive and hypertensive were included.

RESULTS

Twenty-two studies (16 cross-sectional studies, 5 cohorts and one case-control) were eligible. Combining 14 extracted effect sizes showed that higher circulatory/dietary n-6 PUFAs tended to be associated with 10% lower risk of HTN (95% CI: 0.81, 1.00), whereas combining 23 effect sizes illustrated no difference in circulatory/dietary n-6 PUFAs mean levels between normotensive and hypertensive subjects. According to subgroup analysis based on fatty acid types, total n-6 PUFAs (OR = 0.82, 95% CI: 0.70, 0.97) and linoleic acid (OR = 0.56, 95% CI: 0.39, 0.82) were inversely related to the risk of HTN. Circulatory/dietary n-6 PUFAs were correlated neither with systolic nor with diastolic blood pressure.

CONCLUSIONS

Higher circulatory/dietary n-6 PUFAs tend to be associated with lower odds of HTN. Particularly, total n-6 PUFAs and linoleic acid were associated with lower risk of HTN.

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.

Soy product consumption and the risk of major depressive disorder in older adults: Evidence from a cohort study

Background

To explore the association between soy product consumption and the risk of depression in the community.

Methods

In 2014, a total of 10,901 older people were recruited from Zhejiang province, China, and completed food frequency interviews. Participants were followed up over the next 6 years, and depression was assessed at each visit. Finally, 6,253 participants were included in the present study. Mixed effects models were performed to analyze the association by multivariate adjustments for potential confounders.

Results

Over four-fifths of the eligible participants took soy food at least one day per week. The mixed effects model has shown the adjusted odds ratios (95% CI) of high-frequency consumers (4-7 days per week) were 0.46 (0.39-0.54) for depression with a cut-off score of 5, compared with non-consumers.

Conclusions

More frequent soy product consumption was associated with a lower risk of depression.