Adherence to a Mediterranean Diet Is Associated with Lower Depressive Symptoms among U.S. Adults

Intestinal Barrier, Immunity and Microbiome: Partners in the Depression Crime

Depression is a highly prevalent disorder and a leading cause of disability worldwide. It has a major impact on the affected individual and on society as a whole. Regrettably, current available treatments for this condition are insufficient in many patients. In recent years, the gut microbiome has emerged as a promising alternative target for treating and preventing depressive disorders. However, the microbes that form this ecosystem do not act alone but are part of a complicated network connecting the gut and the brain that influences our mood. Host cells that are in intimate contact with gut microbes, such as the epithelial cells forming the gut barrier and the immune cells in their vicinity, play a key role in the process. These cells continuously shape immune responses to maintain healthy communication between gut microbes and the host. In this article, we review how the interplay among epithelial cells, the immune system, and gut microbes mediates gut-brain communication to influence mood. We also discuss how advances in our knowledge of the mechanisms underlying the gut-brain axis could contribute to addressing depression. SIGNIFICANCE STATEMENT: This review does not aim to systematically describe intestinal microbes that might be beneficial or detrimental for depression. We have adopted a novel point of view by focusing on potential mechanisms underlying the crosstalk between gut microbes and their intestinal environment to control mood. These pathways could be targeted by well defined and individually tailored dietary interventions, microbes, or microbial metabolites to ameliorate depression and decrease its important social and economic impact.

Maternal pre-pregnancy diet and prenatal depression: the mediating role of pre-pregnancy weight status and prenatal inflammation

Depression is a common prenatal psychological complication. We aimed to investigate if maternal pre-pregnancy diet can impact prenatal depressive symptoms and the mediating role of pre-pregnancy BMI and inflammation. We used data (N 1141) from the Alberta Pregnancy Outcomes and Nutrition cohort study. We calculated Mediterranean diet adherence (MED) and dietary inflammatory index (DII) scores using data from pre-pregnancy FFQ. In the third-trimester, we assessed depressive symptoms using Edinburgh Postpartum Depression Scale (EPDS) and inflammation through serum C-reactive protein (CRP) levels. BMI was calculated from self-reported pre-pregnancy weight. Race-stratified analyses (white and people of colour) were run. We observed no association between MED or DII tertiles and depressive symptoms. However, white participants in the MED tertile-3 had lower risk of depression (EPDS < 10) compared with tertile-1 (OR = 0·56, 95 % CI, 0·33, 0·95). White individuals in MED tertile-3 had lower BMI (MD = -1·08; 95 % CI, -1·77, -0·39) and CRP (MD = -0·53; 95 % CI, -0·95, -0·11) than tertile-1, and those in DII tertile-2 (MD = 0·44; 95 % CI, 0·03, 0·84) and tertile-3 (MD = 0·42; 95 % CI, 0·01, 0·83) had higher CRP than tertile-1. Among people of colour, neither MED nor DII was associated with BMI or CRP, but BMI was negatively associated with depressive symptoms (β = -0·25, 95 % CI, -0·43, -0·06). We found no association between diet and depressive symptoms through BMI or CRP, in either race. Pre-pregnancy diet might affect the risk of prenatal depression in a race-specific way. Further research is required to explore the racial differences in the association between maternal diet and prenatal depressive symptoms/depression risk.

The Combined Effects of the Most Important Dietary Patterns on the Incidence and Prevalence of Chronic Renal Failure: Results from the US National Health and Nutrition Examination Survey and Mendelian Analyses

BACKGROUND

We aimed to comprehensively assess the relationship of specific dietary patterns and various nutrients with chronic kidney disease (CKD) and its progression.

METHODS

The observational study data were from the NHANES 2005-2020. We calculated four dietary pattern scores (healthy eating index 2020 (HEI-2020), dietary inflammatory index (DII), alternative mediterranean diet (aMed), and dietary approaches to stop hypertension (DASH)) and the intakes of various nutrients and defined CKD, CKD-very high risk, and kidney dialysis. Associations between dietary patterns and nutrients and disease were assessed by means of two logistic regression models. Two-sample MR was performed with various food and nutrients as the exposure and CKD, kidney dialysis as the outcome. Sensitivity analyses were conducted to verify the reliability of the results.

RESULTS

A total of 25,167 participants were included in the analyses, of whom 4161 had CKD. HEI-2020, aMed, and DASH were significantly negatively associated with CKD and CKD-very high risk at higher quartiles, while DII was significantly positively associated. A higher intake of vitamins and minerals may reduce the incidence and progression of CKD to varying degrees. The MR results, corrected for false discovery rates, showed that a higher sodium intake was associated with a higher prevalence of CKD (OR: 3.91, 95%CI: 2.55, 5.99).

CONCLUSIONS

Adhering to the three dietary patterns of HEI-2020, aMed, and DASH and supplementing with vitamins and minerals benefits kidney health.

Association of dietary saturated fatty acid intake with depression: mediating effects of the dietary inflammation index

Background

Diet and dietary inflammation play an important role in depression. The aim of this study was to assess the association of SFAs with depression risk and the mediating role of DII.

Method

Among 22, 478 U.S. adults (≥ 20, years old) according to the National Health and Nutrition Examination Survey (NHANES), univariate logistic regression, and multivariate logistic regression were used to evaluate the association between dietary intake of SFAs and the risk of depression. Dietary inflammation levels were evaluated using the DII. Mediation analysis was used to investigate the risk of DII and depression. The nonlinear relationship between SFAs and depression was assessed using restricted cubic spline (RCS).

Results

There was a significant difference in SFA 6.0 dietary intake between depression and non-depression individuals. After adjusting for potential confounders, multifactorial logistic regression results showed that SFA 8.0 (Q3 1.58 (1.09, 2.30), p-value = 0.017; Q4 1.55 (1.00, 2.42), p-value = 0.050) may increase the prevalence factor for depression, SFA 14.0 (Q3 0.67 (0.47, 0.94), p-value = 0.020) may decrease the risk of depression. There were sex and age differences in the effects of different subtypes of SFAs on depression. Dietary intake of SFA 12.0 content showed a nonlinear relationship with the risk of depression (p-value = 0.005). Furthermore, DII was recognized as a mediator of the association between SFAs and the risk of depression.

Conclusion

The findings suggest that dietary intake of SFAs is associated with the risk of depression in relation to the chain length of SFAs, and this may be due to the mediating effect of DII.

Bidirectional associations between dietary diversity and depressive symptoms in Chinese adult women: A retrospective cohort study

OBJECTIVE

This study aimed to examine the bidirectional associations between dietary diversity and clinical depressive symptoms in adult women, and influencing factors of clinical depressive symptoms.

METHODS

This longitudinal study included a total of 22,385 participants, each of whom underwent at least two data collections. We used convenience sampling to recruit women from a health management center of a general hospital in southern China from April 2015 to December 2021. They completed an online self-reported health questionnaire, which included demographic characteristics, lifestyle information, the Dietary Diversity Scale (DDS), and the Patient Health Questionnaire-9.

RESULTS

New-onset depressive symptoms and low dietary diversity were observed in this study among 1285 and 3223 participants, respectively. Negative associations were observed between baseline low dietary diversity and new-onset depressive symptoms (P < 0.05) and between baseline depressive symptoms and low dietary diversity (P < 0.001). Cross-lagged panel analysis indicated that dietary diversity negatively and prospectively predicted depressive symptoms, but vice versa (P < 0.05). Strong evidence of a nonlinear association between DDS scores and incident depressive symptoms was found (P nonlinear < 0.05) regardless of whether the variables were adjusted. Besides, age, menarche age, physical activity, sleep duration, longer sedentary behavior and other lifestyle factors were influencing factors of depressive symptoms (P < 0.05).

CONCLUSIONS

The present study identified bidirectional associations between dietary diversity and depressive symptoms, and the associations were found to have a non-linear pattern. Adherence to dietary diversity and a healthy lifestyle could be effective non-pharmacological preventive measures to reduce the incidence of depressive symptoms.

Adherence to a Mediterranean type of diet in the world: a geographical analysis based on a systematic review of 57 studies with 1,125,560 participants

This systematic review aimed to assess the level and time-trends of adherence to Mediterranean-type diets (MTD) among the general population, globally. According to Preferred Reporting Items for Systematic Reviews and Meta-Analyses, a comprehensive literature search of the MEDLINE and Scopus databases was carried out, until 04/09/2023, based on specific criteria. Fifty-seven studies with 1,125,560 apparently healthy adults from Europe (n = 37), US (n = 8), Asia (n = 8), Australia (n = 4) and Africa (n = 1) were included. Adherence to an MTD was moderate with a significant decline observed in the last decade. European countries, mainly driven by Mediterranean countries, showed higher adherence than other regions. Geographical analysis revealed that adherence to an MTD is related to both geographic location and socioeconomic status throughout the world.

Adherence to the Mediterranean diet and depression, anxiety, and stress symptoms in Chilean university students: a cross-sectional study

This study aims to determine the association of adherence to the Mediterranean diet and its food groups with depressive symptoms in Chilean university students. The study design was cross-sectional. A total of 934 first-year students at a Chilean public university completed a self-report questionnaire. To assess adherence to Mediterranean diet, an index validated in Chile (Chilean-MDI) was used, and depression, anxiety, and stress symptoms were assessed using the Depression Anxiety and Stress Scale (DASS-21). Logistic regression models were used to analyze the association of adherence to Mediterranean diet and its food groups with depression, anxiety, and stress symptoms adjusted for the main confounders. Students with moderate and high adherence to Mediterranean diet showed lower odds of depression [DASS-21 > 5, odds ratio (OR) = 0.64; 95% confidence interval (95%CI): 0.47-0.88] than those with low adherence to Mediterranean diet. The consumption of 1-2 servings/day of vegetables (OR = 0.63; 95%CI: 0.43-0.92), > 2 servings/week of nuts (OR = 0.41; 95%CI: 0.21-0.80), 1-2 servings/day of fruits (OR = 0.60; 95%CI: 0.42-0.85), 1-2 servings/week of fish and seafood (OR = 0.67; 95%CI: 0.48-0.94), and 1/2-3 units/week of avocado (OR = 0.67; 95%CI: 0.48-0.93) showed low odds of depressive symptoms. The consumption of whole grains and cereals (> 2 servings/day) (OR = 1.63; 95%CI: 1.02-2.61) showed the opposite association. Adherence to Mediterranean diet and consumption of fruits, vegetables, nuts, avocado, fish, and seafood are associated with a lower likelihood of depression in Chilean university students. New policies and educational strategies are recommended to improve diet quality and the mental health of the entire university community.

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.

Mediterranean Diet Adherence and Depressive Symptoms among a Nationally Representative Sample of Pregnant Women in the United States

BACKGROUND

Prenatal depression affects ∼12% of pregnant women in the United States and is associated with an increased risk of adverse birth outcomes and maternal mortality. Adherence to a healthy dietary pattern may reduce and/or protect against depressive symptoms.

OBJECTIVES

To investigate the relationship between adherence to a Mediterranean diet and depressive symptoms among pregnant women in the United States.

METHODS

We used data from the National Health and Nutrition Examination Survey (2005-2018, N = 540) and included pregnant women aged 18-44 y with a positive urine pregnancy test. The Mediterranean diet score (aMED) was calculated from 1 24-h recall; aMED typically ranges from 0-9, but in these analyses, it ranged from 0-8 because alcohol was not included. The aMED score was dichotomized as high (>3) compared with low (≤3). The Patient Health Questionnaire-9 (PHQ-9), which measures depressive symptoms, was dichotomized as lower compared with higher (PHQ-9 score ≥10), based on the clinical cutoff for patient referral. Our primary model employed logistic regression to investigate the association between aMED adherence and high depressive symptoms when controlling for socio-demographics (age, racial/ethnicity, education, poverty, and relationship status), total calories, and prepregnancy body mass index (kg/m2). We also modeled the PHQ-9 score as a continuous variable using a random-effects model.

RESULTS

About 5% of pregnant women had moderate to severe depressive symptoms, and 45% were highly adherent to a Mediterranean diet. Higher adherence to a Mediterranean diet was associated with lower odds of depressive symptoms (odds ratio: 0.31, 95% confidence interval: 0.10, 0.98). Results were not significant for the continuous PHQ-9 score (β: -0.30; 95% confidence interval: -0.90, 0.30).

CONCLUSIONS

Adherence to a Mediterranean diet may have the potential to lower depressive symptoms among pregnant women; however, these results should be interpreted with caution. Nevertheless, considering the public health significance of promoting mental wellness among pregnant women, this relationship merits further examination using experimental designs.

Relationship between Mediterranean diet and depression in South Korea: the Korea National Health and Nutrition Examination Survey

Background

Several studies have shown that adherence to the Mediterranean diet is associated with a lower risk of depression; however, little is known about the Asian population. This study investigated the relationship between adherence to the Mediterranean diet and depression in a sample of the South Korean population.

Methods

In total, 5,849 adults from the 2014 and 2016 Korea National Health and Nutrition Examination Surveys were included in the study. The Mediterranean diet adherence was measured using a modified alternate Mediterranean diet score (mMED) developed to adjust for Korean dietary patterns. The mMED scores using the Food Frequency Questionnaire were divided into four categories (0-2, 3-4, 5-6, and 7-9 points). Subjects with depression were defined as having moderate-to-severe depressive symptoms using the Patient Health Questionnaire-9, with a cutoff value of 10. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). A subgroup analysis was performed based on sex.

Results

The results of logistic regression analysis indicated that individuals with higher mMED were 42-73% less likely to report depression compared to individuals with the lowest mMED [ORs (95% CIs) =0.58 (0.37-0.90), 0.50 (0.31-0.80), 0.27 (0.15-0.47)] after adjusting for socio-demographic and health-related variables. In women, individuals with mMED of 7-9 had 71% lower odds of depression [ORs (95% CIs): 0.29 (0.13-0.64)]. In men, individuals with mMED of 5-9 had 55% [ORs (95% CIs): 0.45 (0.23-0.91)] to 79% [ORs (95% CIs): 0.21 (0.08-0.57)] lower odds of depression.

Conclusion

This study suggests that adherence to the Mediterranean diet is inversely associated with depression in both men and women among Korean adults. This study provides evidence that a Mediterranean diet is crucial in preventing depressive symptoms in Asian populations.

The gut-derived metabolites as mediators of the effect of healthy nutrition on the brain

Nutrition is now well recognized to be an environmental factor which positively or negatively influences the risk to develop neurological and psychiatric disorders. The gut microbiota has recently been shown to be an important actor mediating the relationship between environmental factors, including nutrition, and brain function. While its composition has been widely studied and associated with the risk of brain diseases, the mechanisms underlying the relationship between the gut and brain diseases remain to be explored. The wide range of bioactive molecules produced by the gut microbiota, called gut-derived metabolites (GDM), represent new players in the gut to brain interactions and become interesting target to promote brain health. The aim of this narrative review is to highlight some GDMs of interest that are produced in response to healthy food consumption and to summarize what is known about their potential effects on brain function. Overall, GDMs represent future useful biomarkers for the development of personalized nutrition. Indeed, their quantification after nutritional interventions is a useful tool to determine individuals' ability to produce microbiota-derived bioactive compounds upon consumption of specific food or nutrients. Moreover, GDMs represent also a new therapeutic approach to counteract the lack of response to conventional nutritional interventions.

The Brain-Gut-Microbiota Interplay in Depression: a key to design innovative therapeutic approaches

Depression is the most prevalent mental disorder in the world associated with huge socio-economic consequences. While depressive-related symptoms are well known, the molecular mechanisms underlying disease pathophysiology and progression remain largely unknown. The gut microbiota (GM) is emerging as a key regulator of the central nervous system homeostasis by exerting fundamental immune and metabolic functions. In turn, the brain influences the intestinal microbial composition through neuroendocrine signals, within the so-called gut microbiota-brain axis. The balance of this bidirectional crosstalk is important to ensure neurogenesis, preserve the integrity of the blood-brain barrier and avoid neuroinflammation. Conversely, dysbiosis and gut permeability negatively affect brain development, behavior, and cognition. Furthermore, although not fully defined yet, changes in the GM composition in depressed patients are reported to influence the pharmacokinetics of common antidepressants by affecting their absorption, metabolism, and activity. Similarly, neuropsychiatric drugs may shape in turn the GM with an impact on the efficacy and toxicity of the pharmacological intervention itself. Consequently, strategies aimed at re-establishing the correct homeostatic gut balance (i.e., prebiotics, probiotics, fecal microbiota transplantation, and dietary interventions) represent an innovative approach to improve the pharmacotherapy of depression. Among these, probiotics and the Mediterranean diet, alone or in combination with the standard of care, hold promise for clinical application. Therefore, the disclosure of the intricate network between GM and depression will give precious insights for innovative diagnostic and therapeutic approaches towards depression, with profound implications for drug development and clinical practice.

Bibliometric mapping of the landscape and structure of nutrition and depression research: visualization analysis

BACKGROUND

Numerous epidemiological studies have examined the relationship between dietary intake of specific foods or nutrients and the incidence of depression and have noted that nutrition has a significant impact on mental health. Therefore, the purpose of this study is to assess the state of research, the frontiers of research, and development trends in the field of nutrition and depression using bibliometric and visual analysis.

METHODS

We collected publications on the topic of nutrition and depression from Scopus between 2002 and 2021. Subsequently, we utilized VOSviewer 1.6.18 and Microsoft Excel 2013 to perform bibliometric analysis and visualization. Bibliometric analysis involves retrieving documents from a singular database, such as SciVerse Scopus or Web of Knowledge, and subjecting them to quantitative and qualitative analysis. Notably, gray literature is not considered in bibliometric analysis.

RESULTS

A total of 2171 publications on nutrition and depression were found between 2002 and 2021, namely 1855 (85.44%) original articles, 190 (8.75%) reviews, 38 (1.75%) letters, and 88 (4.05%) other types of publications. The most productive country was found to be the USA (n = 726; 33.44%), followed by Australia (n = 172; 7.92%), the United Kingdom (n = 158; 7.28%), China (n = 132; 6.08%), and Canada (n = 131; 6.03%). The remaining publications were from other countries (n = 852; 39.25%). According to the citation analysis, the retrieved papers were cited on an average of 26.6 times and had an h-index of 105 with 57,781 citations. The most frequent terms on the map include those related to (a) fatty acid links to depression and brain inflammation, (b) depression and eating disorders, and finally, (c) adherence to the Mediterranean diet and risk of depression.

CONCLUSIONS

The current study was the first novel bibliometric analysis of nutrition and depression research that used data extracted from Scopus for visualization network mapping. In recent years, the theme "Mediterranean diet adherence and risk of depression" has been identified more frequently, indicating that studies in this field have garnered considerable attention and reflect the most recent scientific advances. Researchers should continue to investigate nutrition and depression, and we believe this study provides significant information for researchers, nutritionists, and clinicians.

Cross-Sectional Analysis of the Relationship Between Adherence to the Mediterranean Diet and Mental Wellness

The purpose of the study was to determine whether there was a relationship between adherence to the Mediterranean diet (MD) and levels of anxiety, depression, and overall mental well-being. The Mediterranean diet is a popular, healthy diet, aimed to promote wellness and reduce chronic illness. In order to determine the relationship between MD and mental well-being, 100 participants consented to complete an online survey to analyze their adherence to MD, along with levels of anxiety and depression. The validated questionnaires of the 14-item Questionnaire of Mediterranean diet Adherence, Generalized Anxiety Disorder-7 (GAD-7), and Beck's Depression Inventory (BDI) assessments were used to analyze each participant. To evaluate the results of the study, Spearman's rank correlation coefficient analysis was used to identify relationships between MD, depression, and anxiety. There was a significant negative correlation, indicating that MD adherence is associated with reduced depression and anxiety.

Dietary Fats and Depressive Symptoms in Italian Adults

BACKGROUND

Depression represents one of the major causes of disability worldwide, with an important socioeconomic cost. Although many risk factors have been considered in its pathogenesis, nutrition seems to play a determinant role in its prevention. With regard to individual macronutrients, dietary fats and especially n-3 polyunsaturated fatty acids (n-3 PUFA) are the most studied. However, previous data about other dietary fatty acids, such as n-6 PUFA, are conflicting, and little is known about saturated fatty acids (SFA), especially when considering carbon chain length. Thus, we investigated whether single types and subtypes of dietary fats are related to depressive symptoms in Italian individuals living in the Mediterranean area.

METHODS

Dietary and socio-demographic data of 1572 individuals were analyzed. Food frequency questionnaires (FFQs) were used to determine the consumption of total dietary fat and each specific class of dietary fat, such as SFA, monounsaturated fatty acid (MUFA), and PUFA. The intake of fatty acids was also assessed according to the carbon-chain length of each single class. The Center for Epidemiologic Studies Depression Scale (CES-D) was used as a screening tool for depressive symptoms.

RESULTS

After adjustment for potential confounding factors, a significant inverse association between low/moderate levels of PUFA intake and depressive symptoms (Q2 vs. Q1, odds ratio (OR) = 0.60, 95% CI: 0.44, 0.84) was found. On the other hand, moderate saturated fat consumption was associated with depressive symptoms (Q3 vs. Q1, OR = 1.44, 95% CI: 1.02, 2.04). However, when considering carbon chain length, individuals with a lower to moderate intake of short-chain saturated fatty acids (SCSFA) and medium-chain saturated fatty acids (MCSFA) were less likely to have depressive symptoms (Q3 vs. Q1, OR = 0.48, 95% CI: 0.31, 0.75), while moderate intake of arachidic acid (C20:0) was directly associated with depressive symptoms (Q3 vs. Q1, OR = 1.87, 95% CI: 1.26, 2.77). Among single MUFAs, higher myristoleic acid (C14:1) intake was directly associated with depressive symptoms (Q4 vs. Q1, OR = 1.71, 95% CI: 1.12, 2.61), while moderate intake of erucic acid (C22:1) was associated with lower odds of having depressive symptoms (Q3 vs. Q1, OR = 0.54, 95% CI: 0.33, 0.86). When considering individual PUFAs, individuals with moderate and higher intakes of arachidonic acid (C20:4) were less likely to have depressive symptoms (OR = 0.64, 95% CI: 0.45, 0.91; OR = 0.59, 95% CI: 0.38, 0.91, respectively). Similarly, higher eicosapentaenoic acid (C20:5) intake was inversely associated with depressive symptoms (Q4 vs. Q1, OR = 0.35, 95% CI: 0.12, 0.98), while a significant association for docosahexaenoic acid (C22:6) was retrieved only for low intakes (Q2 vs. Q1, OR = 0.33, 95% CI: 0.12, 0.88).

CONCLUSIONS

Dietary fat intake may be associated with depressive symptoms, underlying the importance of distinguishing between different fat types. This study confirms the pivotal role of PUFAs and reopens the debate on the role of saturated fatty acids, suggesting plausible effects of moderate intakes of short-chain fatty acids.

Anti-Inflammatory, Antioxidant, and Neuroprotective Effects of Polyphenols-Polyphenols as an Element of Diet Therapy in Depressive Disorders

Depressive disorders can affect up to 350 million people worldwide, and in developed countries, the percentage of patients with depressive disorders may be as high as 10%. During depression, activation of pro-inflammatory pathways, mitochondrial dysfunction, increased markers of oxidative stress, and a reduction in the antioxidant effectiveness of the body are observed. It is estimated that approximately 30% of depressed patients do not respond to traditional pharmacological treatments. However, more and more attention is being paid to the influence of active ingredients in food on the course and risk of neurological disorders, including depression. The possibility of using foods containing polyphenols as an element of diet therapy in depression was analyzed in the review. The possibility of whether the consumption of products such as polyphenols could alleviate the course of depression or prevent the progression of it was also considered. Results from preclinical studies demonstrate the potential of phenolic compounds have the potential to reduce depressive behaviors by regulating factors related to oxidative stress, neuroinflammation, and modulation of the intestinal microbiota.

Dietary intervention in depression - a review

Depression is a mental illness that affects the normal lives of over 300 million people. Unfortunately, about 30% to 40% of patients do not adequately respond to pharmacotherapy and other therapies. This review focuses on exploring the relationship between dietary nutrition and depression, aiming to find safer and efficient ingredients to alleviate depression. Diet can affect depression in numerous ways. These pathways include the regulation of tryptophan metabolism, inflammation, hypothalamic-pituitary-adrenal (HPA) axis, microbe-gut-brain axis, brain-derived neurotrophic factor (BDNF) and epigenetics. Furthermore, probiotics, micronutrients, and other active substances exhibit significant antidepressant effects by regulating the above pathways. These provide insights for developing antidepressant foods.

Non-linear association between Mediterranean diet and depressive symptom in U.S. adults: A cross-sectional study

The Mediterranean diet (MED), a dietary pattern rich in fruits and vegetables, whole grains, legumes, nuts, fish, and olive oil, has anti-oxidative and anti-inflammatory effects. Although some data suggest that MED adherence is associated with decreased manifestation of depressive symptoms, it remains necessary to further analyze this apparent non-linear association as well as the influence of different factors on the relationship between MED and depression. Here, we investigated associations between the alternate MED (aMED) score and depressive symptom via multivariate logistic regression, weighted generalized additive (GAM) and two-step linear regression models, analyzing data from the 2005-2018 National Health and Nutrition Examination Survey (NHANES). The most important factor relevant to aMED score that contributed to the prevalence of depressive symptom was assessed using random forest. Furthermore, we examined whether the relationship between aMED score and depressive symptom differs by age, race, sex, socioeconomic variables, lifestyle- and health-related variables, and chronic medical conditions, via subgroup analyses. A total of 19,477 participants (20-80 years of age) were included in this cross-sectional study. In crude and adjusted (1-5) multivariate logistic regression models, increased aMED score was noted to associate with non-depressive status, as defined using the Patient Health Questionnaire-9 (P < 0.05). Data analyses via GAM and two-piecewise linear regression revealed a non-linear association between aMED and depressive symptom, which had an inflection point of 3. Random forest results revealed that vegetable score contributes greatest to the relationship between aMED and depressive symptom. Subgroup analyses revealed that aMED score is significantly negatively related with depressive symptom in most different populations (P < 0.05) with the exception of high annual income, diabetes, borderline blood glucose level and Parkinson's disease (PD) (P > 0.05). In conclusion, we observed a non-linear association between aMED score and depressive symptom. Further studies are needed to validate our results.