The Dietary Inflammatory Index, shift work, and depression: Results from NHANES

Is there a link between the inflammatory potential of a diet and mental health among patients with migraine? Findings from a cross-sectional survey

AIMS

In this study, we aimed to evaluate the relationship between the dietary inflammatory index (DII) and mental health outcomes among patients with migraine headaches.

METHODS

In this cross-sectional study, 262 subjects were included. The dietary intakes were collected using a validated 168-item semi-quantitative food frequency questionnaire. Items were scored according to their inflammatory potential, so a higher DII indicated a more pro-inflammatory diet. The association between DII and the mental health of participants was investigated using multinomial logistic regression and odds ratio (OR) with a corresponding 95% confidence interval (CI) was reported.

RESULTS

Overall, 224 women and 38 men, with a mean (standard error) DII of -2.96 (0.06), age of 36.1 (0.53) years, and BMI of 25.55 (0.21) kg/m2, comprised our study population. DII was positively associated with a higher risk of depression in patients with the highest adherence to a pro-inflammatory diet compared to those with the lowest adherence (OR = 1.76; 95%CI: 1.04, 3.00; Ptrend = 0.035). Adjustments for age, sex, marital status, smoking status, migraine headache index score, number of family members, mean arterial pressure, medication, physical activity, and BMI intensified the association in a way that the risk of depression was 2.03 times higher in patients with the highest adherence to a pro-inflammatory diet compared to those with the lowest adherence to a pro-inflammatory diet (OR = 2.03; 95%CI: 1.18, 3.49; Ptrend = 0.011).

CONCLUSION

Our findings suggest that depression was positively associated with adherence to a pro-inflammatory diet. However, no significant association was observed between anxiety and stress with DII.

Dietary inflammatory index and neuropsychiatric disorders

Neuropsychiatric disorders (NPDs) are considered a potential threat to mental health. Inflammation predominantly plays a role in the pathophysiology of NPDs. Dietary patterns are widely postulated to be involved in the physiological response to inflammation. This review aims to discuss the literature on how dietary inflammatory index (DII) is related to inflammation and, consequently, NPDs. After comprehensive scrutiny in different databases, the articles that investigated the relation of DII score and various NPDs and psychological circumstances were included. The association between dietary patterns and mental disorders comprising depression, anxiety, and stress proved the role of a proinflammatory diet in these conditions' exacerbation. Aging is another condition closely associated with DII. The impact of proinflammatory and anti-inflammatory diet on sleep quality indicated related disorders like sleep latency and day dysfunctions among the different populations are in relation with the high DII score. The potential effects of genetic backgrounds, dietary patterns, and the gut microbiome on DII are discussed as well. To plan preventive or therapeutic interventions considering the DII, these factors, especially genetic variations, should be considered as there is a growing body of literature indicating the role of personalized medicine in different NPDs. To the best of our knowledge, there is a limited number of RCTs on this subject, so future research should evaluate the causality via RCTs and look for therapeutic interventions with an eye on personalized medicine using information about DII in NPDs.

Association between dietary inflammatory index and mental disorders using multilevel modeling with GLIMMIX

Introduction

The Dietary Inflammatory Index (DII) is a composite nutritional index that has gained significant attention in the past decade due to its association with physical and mental well-being. To accurately assess the precise effects of DII on health outcomes, the effects of nutrients and foods need to be adjusted. This study aimed to investigate the association between DII and mental disorders (depression, anxiety, and stress) using multilevel modeling to minimize the bias of the previous methods.

Methods

This cross-sectional analytical study was conducted using data from the initial phase of the Tehran University of Medical Sciences Employees' Cohort Study (TEC). Nutritional information was obtained through a dish-based semi-quantitative food frequency questionnaire (DFQ), while psychological data were collected using the depression, anxiety and stress scale (DASS-42). The acquired data were analyzed using multilevel modeling in three levels (foods, nutrients, and DII, respectively) through GLIMMIX in the SAS software.

Results

A total of 3,501 individuals participated in this study. The results of the multilevel model demonstrated a significant statistical association between DII and mental disorders after adjusting for baseline characteristics, nutrients and foods. For each unit increase in DII, the mean scores for stress, anxiety, and depression increased by 3.55, 4.26, and 3.02, respectively (p < 0.001).

Conclusion

Based on the multilevel model's findings, it is recommended to minimize the use of pro-inflammatory nutrients and foods to increase the mental health. Multilevel data analysis has also been recommended in nutritional studies involving nested data to obtain more accurate and plausible estimates.

Association between empirical dietary inflammatory index, odds, and severity of anxiety disorders: A case-control study

Diet may be a modifiable factor in the prevention of psychiatric disorders by modulating inflammation. In this study, we evaluated the association between empirical dietary inflammatory index (EDII) that is designed to evaluate the inflammatory potential of diets and anxiety disorders (AD) in adults. This case-control study was carried out on 85 patients who were group matched by gender with 170 healthy subjects. Data for dietary intake were assessed by using a 147-item validated food frequency questionnaire (FFQ). Anthropometric measures were collected using standard methods. EDII score was developed according to participants' dietary intakes of 28 predefined food groups. Multivariate odds ratios (OR) with 95% confidence intervals (CI) were used to investigate the association of empirically derived inflammatory potential of the diet and anxiety disorder. We observed that after adjusting for confounders, individuals in the top category of EDII score were 2.09 fold more likely to have anxiety disorder compared with those in the bottom category (OR: 2.09, 95% CI: 1.01, 4.33). Also, higher EDII contributed to a higher GAD-7 score (p < .001). There was a significant positive linear association between EDII and AD (β = 3.64, p < .001). After controlling for potential confounders AD had a strong positive correlation with the EDII score (r = .61, p-value <.001). In conclusion, in this case-control study, we realized that there is a positive association between the EDII score, odds, and severity of anxiety disorder. Ultimately, the potential role necessitates clarifying this association by conducting large-population prospective cohort studies.

Association between inflammatory potential of diet and self-reported severe headache or migraine: A cross-sectional study of the National Health and Nutrition Examination Survey

OBJECTIVE

Inflammation plays an important role in migraine development. Dietary interventions that reduce the inflammatory state are effective for migraine prophylaxis. However, little is yet known about the association between the inflammatory potential of diet and migraine in the general US adult population. The aim of this study was to evaluate whether the inflammatory potential of diet is associated with severe headache or migraine in US adults.

METHODS

This cross-sectional study analyzed data from adult participants in the 1999-2004 National Health and Nutrition Examination Survey. Severe headache or migraine was determined based on self-reported information. Severe headache or migraine was defined as an affirmative response to the question: "Have you had a severe headache or migraine in the past 3 mo?" The dietary inflammatory index (DII) was used to assess the inflammatory potential of the diet. Multivariable logistic regression models were used to determine the odds ratio (OR) and 95 % confidence interval (95% CI) for the association between DII and severe headache or migraine. A multivariable-adjusted restricted cubic spline model was constructed to establish the OR curves at 3 knots to examine the possible non-linear dose-response association between DII and severe headache or migraine.

RESULTS

Of 10359 participants included in this study (mean age, 46.3 [0.3] y; 5116 [49%] men), 2083 (22%) reported previous episodes of severe headache or migraine, whereas 8276 (78%) did not. After adjusting for potential confounders, the DII score was associated with severe headache or migraine (odds ratio [OR], 1.09; 95% confidence interval [CI], 1.03-1.15; P = 0.003). Compared with participants with the lowest tertile (T1) of DII score (i.e., T1; ≤-4.42 to ≤0.77), those with the highest tertile (i.e., T3; <2.44 to ≤5.18) had an adjusted OR for severe headache or migraine of 1.46 (95% CI, 1.20-1.77; P < 0.001). The multivariable restricted cubic spline showed a non-linear association between DII and severe headache or migraine (P = 0.012). In two piecewise regression models, the adjusted OR of developing a severe headache or migraine was 1.19 (95% CI, 1.04-1.37; P = 0.012) in participants with a DII score ≥1.48, whereas there was no association between DII and severe headache or migraine in participants with a DII score <1.48. Subgroup analyses showed that DII was associated with severe headache or migraine in women (OR, 1.73; 95% CI, 1.31-2.28), individuals 20 to 50 y of age (OR, 1.66; 95% CI, 1.29-2.14), those who were married or living with a partner (OR, 1.49; 95% CI, 1.19-1.85), individuals living alone (OR, 1.36; 95% CI, 1.02-1.81), those with a high level of education (OR, 1.72; 95% CI, 1.26-2.36), individuals with a low family income (OR, 1.58; 95% CI, 1.10-2.28), those with a medium or high family income (OR, 1.48; 95% CI, 1.17-1.86), and body mass index <25 kg/m2 (OR, 1.71; 95% CI, 1.21-2.41).

CONCLUSION

The inflammatory potential of the diet is associated with severe headache or migraine in US adults.

Association of shift work and dietary inflammatory potential with all-cause death among us hypertensive population: national health and nutrition examination study, 2005-2010

BACKGROUND & AIMS

The individual effect of working schedule on survival in the hypertensive population has not been adequately studied. Shiftworkers are also prone to unhealthy lifestyles like pro-inflammatory diet. Therefore, we assessed the effect of shift work and its joint association with dietary inflammatory potential on mortality risk among the large US nationally representative sample of adult hypertensive population.

METHODS

Data were from a nationally representative prospective cohort among US hypertensive population (n = 3680; weighted population, 54,192,988). The participants were linked to the 2019 public-access linked mortality archives. The working schedule were self-reported using the Occupation Questionnaire Section. Dietary inflammatory index (DII) scores were equally calculated using the 24-hour dietary recall (24 h) interviews. Multivariable Cox proportional hazards regression models were used to estimate hazard ratio and 95% confidence intervals (95%CI) for survival of hypertension individuals by work schedule and dietary inflammatory potential. The joint effect of work schedule and dietary inflammatory potential was then examined.

RESULTS

Among the 3680 hypertension individuals (39.89% female [n = 1479] and 71.42% white [n = 1707]; weighted mean [SE] age, 47.35 [0.32] years), 592 individuals reported shift work status. 474 (10.76%) reported shift work status with pro-inflammatory dietary pattern (DII scores > 0). 118 (3.06%) reported shift work status with anti-inflammatory dietary pattern (DII scores < 0). 646 (19.64%) reported a non-shift working schedule with anti-inflammatory dietary pattern, while 2442 (66.54%) reported non-shift working schedule with pro-inflammatory dietary pattern. After a median follow-up of 11.67 years (140 months), 317 deaths (cardiovascular diseases (CVD), 65; cancer, 104) were registered. Cox regression analysis showed that shift work was associated with higher risk of all-cause mortality (hazard ratio [HR], 1.48; 95% CI, 1.07-2.06) compared with non-shift workers. In the joint analysis, shift work status combined with pro-inflammatory dietary pattern was associated with the highest all-cause mortality risk. Moreover, adopting the anti-inflammatory diet significantly attenuates the deleterious effect of shift work on mortality risk.

CONCLUSIONS

In this large representative sample of adults with hypertension in the U.S., the combination of shift work status with pro-inflammatory dietary pattern was highly prevalent and was associated with the highest risks of death from all causes.

Association between dietary inflammatory index and atherosclerosis cardiovascular disease in U.S. adults

Objective

To evaluate the association between dietary inflammatory index (DII) and Atherosclerotic cardiovascular disease (ASCVD) among U.S. adults.

Methods

We collected data from National Health and Nutrition Examination Survey (NHANES) between 1999 and 2018. Adults who reported complete information to diagnose ASCVD and calculate DII were included. We used three models to differentially adjust the covariates, including age, sex, race or ethnicity, education level, smoking status, poverty, insurance, body mass index, hyperlipemia, hypertension, and diabetes. Logistic regression was used to estimate the Odds Ratio (OR) and 95% confidence interval (95% CI) for ASCVD grouped by DII deciles. We additionally conducted spline smoothing with the generalized additive model (GAM) and the log-likelihood ratio to examine the non-linear relationship between DII and ASCVD. If exists, the segmented linear regression will be used to detect the cutoff point. The subgroup analyses were stratified by various atherosclerotic cardiovascular diseases (i.e., CHD, angina, heart attack, and stroke) and sex.

Results

A total of 48,733 participants (mean age, 47.13 ± 0.19 years) with 51.91% women were enrolled, of which 5,011 were diagnosed with ASCVD. In the crude model, participants in the five highest deciles (D6, 7, 8, 9, and 10) of DII score had a significantly higher risk of having ASCVD compared to those in the first decile. In the fully adjusted model, those in the tenth decile [OR = 1.47, 95% CI = (1.18,1.84)] of DII had a significantly increased risk of ASCVD compared to the first decile. Notably, when DII is above 3, the ASCVD risk increased by 41% for each one increase in DII [OR = 1.41, 95% CI = (1.15,1.73)]. This relationship was more pronounced in females.

Conclusion

Our study revealed a positive and non-linearly association between DII and ASCVD in U.S. adults. This relationship was more pronounced in females. The findings provide a reference for future research and diet recommendations.

Dietary inflammatory index and osteoporosis: the National Health and Nutrition Examination Survey, 2017-2018

PURPOSE

The dietary inflammatory index (DII) is a scoring system to quantify the inflammatory effects of nutrients and foods. Inflammation may affect bone health. The purpose of this study was to explore the relationships of DII with bone mineral density (BMD) and osteoporosis.

METHODS

This study involved 1023 women and 1080 men (age ≥ 50) in the US National Health and Nutrition Survey (NHANES), 2017-2018. Multivariable linear regression models were used to estimate the associations between DII and BMD. Association between DII and osteoporosis was tested with multivariable logistic regression models.

RESULTS

In women, DII was negatively associated with total hip and femoral neck BMD after adjusting for covariates (P &lt; 0.05). In men, DII was negatively associated with lumbar spine BMD (P &lt; 0.05). DII was positively associated with osteoporosis in women (P &lt; 0.05). The odds ratios (ORs) (95% CI) for osteoporosis associated with DII quartiles 2, 3 and 4 vs. quartile 1 were 2.95 (1.08, 8.09), 5.63 (2.87, 11.04), and 6.14(2.55, 14.78), respectively. No significant association was observed in men.

CONCLUSIONS

Higher DII scores were associated with increase osteoporosis risk in women, while no association was found in men. Greater pro-inflammatory diets might be associated with lower BMD in both women and men.

Dietary inflammatory potential and the incidence of depression and anxiety: a meta-analysis

The potential modifiable role of diet in common psychological disorders, including depression and anxiety, has attracted growing interest. Diet may influence the occurrence of mental disorders through its inflammatory characteristics. The purpose of this meta-analysis was to explore whether dietary inflammatory potential is associated with the risk of depression and anxiety. A systematic literature search was conducted in PubMed, Web of Science, and Embase databases up to February 2021. Articles related to dietary inflammatory potential and risk of depression or anxiety were included. After the elimination of repetitive and irrelevant literature, we conducted quality assessment, publication bias, and sensitivity analysis. In total, 17 studies with a total of 157,409 participants were included in the final analysis. Compared with the lowest inflammatory diet group, the highest group was significantly associated with the incidence of depression and anxiety, with the following pooled odds ratios (ORs) and 95% confidence intervals (95% CIs): 1.45 (1.30 ~ 1.62) for depression and 1.66 (1.41 ~ 1.96) for anxiety. A subgroup analysis by gender showed that this association was more prominent in women. For depression, the increased risk was 49% in women (OR 1.49, 95% CI 1.28 ~ 1.74) and 27% in men (OR 1.27, 95% CI 1.06 ~ 1.52). As for anxiety, the increased risk was 80% in women (OR 1.80, 95% CI 1.30 ~ 2.49) and 47% in men (OR 1.53, 95% CI 0.81 ~ 2.89). As a result, long-term anti-inflammatory eating patterns may prevent depression and anxiety, whereas pro-inflammatory eating patterns may promote these conditions. People should add more fish, fish oil, fresh fruit, walnuts, and brown rice to their diet.

Potential effects of shift work on skin autoimmune diseases

Shift work is associated with systemic chronic inflammation, impaired host and tumor defense and dysregulated immune responses to harmless antigens such as allergens or auto-antigens. Thus, shift workers are at higher risk to develop a systemic autoimmune disease and circadian disruption with sleep impairment seem to be the key underlying mechanisms. Presumably, disturbances of the sleep-wake cycle also drive skin-specific autoimmune diseases, but epidemiological and experimental evidence so far is scarce. This review summarizes the effects of shift work, circadian misalignment, poor sleep, and the effect of potential hormonal mediators such as stress mediators or melatonin on skin barrier functions and on innate and adaptive skin immunity. Human studies as well as animal models were considered. We will also address advantages and potential pitfalls in animal models of shift work, and possible confounders that could drive skin autoimmune diseases in shift workers such as adverse lifestyle habits and psychosocial influences. Finally, we will outline feasible countermeasures that may reduce the risk of systemic and skin autoimmunity in shift workers, as well as treatment options and highlight outstanding questions that should be addressed in future studies.

Longitudinal and cross-sectional associations between the dietary inflammatory index and objectively and subjectively measured sleep among police officers

Police officers experience exposures associated with increased inflammation, such as the stress associated with shiftwork and poor-quality diet, both of which have been shown to affect sleep duration and quality. This study examined the longitudinal and cross-sectional effects of the Energy-density Dietary Inflammatory Index (E-DII™) on objectively and subjectively measured sleep among police officers. Data were derived from the Buffalo Cardio-Metabolic Occupational Police Stress Cohort (n = 464 at baseline), with longitudinal data collected from 2004 to 2019. A food frequency questionnaire obtained estimated dietary intake from which E-DII scores were calculated. Dependent variables were objectively (Micro Motion Logger Sleep Watch™) and subjectively (Pittsburgh Sleep Quality Index) measured sleep quality and quantity. The analyses included a series of linear mixed-effects models used to examine cross-sectional and longitudinal associations between the E-DII and sleep quantity and quality. Cross-sectionally, more pro-inflammatory diets were associated with higher wake-after-sleep-onset but improved subjective sleep quality. In models accounting for both longitudinal and cross-sectional effects, for every 1-unit increase in the E-DII scores over time (representing a pro-inflammatory change), wake-after-sleep-onset increased by nearly 1.4 min (p = 0.07). This result was driven by officers who primarily worked day shifts (β = 3.33, p = 0.01). Conversely, for every 1-unit increase in E-DII score, the Pittsburgh Sleep Quality Index global score improved. More pro-inflammatory diets were associated with increased wake-after-sleep-onset, an objective measure of sleep quality. Intervention studies to reduce dietary inflammatory potential may provide greater magnitude of effect for changes in sleep quality.

Association of Dietary Inflammatory Index (DII) and Depressive Disorders

A lot of evidence shows that inflammation is related to the development of depression. However, the heterogeneity of depression hinders efforts to understand, prevent and treat this disease. The purpose of this comprehensive review is to summarize the links between inflammation and the established core features of depression, which show more homogeneity than the syndrome itself: overreaction to negative information, changes in reward processing, and cognitive control decline, and somatic syndrome. For each core feature, we first briefly outline its relevance to depression and neurobiological basis, and then review the evidence to investigate the potential role of inflammation. We mainly focus on the discovery of the experimental paradigm of exogenous inflammation. We concluded that inflammation may play a role in overreaction to negative information, altered reward responses, and physical symptoms. There is less evidence to support the effect of inflammation on cognitive control by standard neuropsychological measures. Finally, we discussed the implications for future research and recommendations on how to test the role of inflammation in the pathogenesis of heterogeneous mental illness.

Biological, Psychological, and Social Determinants of Depression: A Review of Recent Literature

Depression is one of the leading causes of disability, and, if left unmanaged, it can increase the risk for suicide. The evidence base on the determinants of depression is fragmented, which makes the interpretation of the results across studies difficult. The objective of this study is to conduct a thorough synthesis of the literature assessing the biological, psychological, and social determinants of depression in order to piece together the puzzle of the key factors that are related to this condition. Titles and abstracts published between 2017 and 2020 were identified in PubMed, as well as Medline, Scopus, and PsycInfo. Key words relating to biological, social, and psychological determinants as well as depression were applied to the databases, and the screening and data charting of the documents took place. We included 470 documents in this literature review. The findings showed that there are a plethora of risk and protective factors (relating to biological, psychological, and social determinants) that are related to depression; these determinants are interlinked and influence depression outcomes through a web of causation. In this paper, we describe and present the vast, fragmented, and complex literature related to this topic. This review may be used to guide practice, public health efforts, policy, and research related to mental health and, specifically, depression.

Diet Quality According to Mental Status and Associated Factors during Adulthood in Spain

Common mental disorders (CMD) are characterized by non-psychotic depressive symptoms, anxiety and somatic complaints, which affect the performance of daily activities. This study aimed to analyze prevalence of diet quality among adults with and without CMD from 2006 to 2017, to study the frequency of food consumption and diet quality according to mental status and age, and to determine which sociodemographic, lifestyle and health-related factors are associated with poor/moderate diet quality, according to mental status. A nationwide cross-sectional study was performed in adults with (n = 12,545) and without CMD (n = 48,079). The data were obtained from three Spanish National Health Surveys (2006, 2011/2012 and 2017). Two logistic regression analyses were used to identify factors associated with diet quality in people with and without CMD. Among those with CMD, the probability of having poor/moderate diet quality was significantly lower for overweight or obese people and those who took part in leisure-time physical activity. Among those without CMD, university graduates were less likely to have a poor/moderate diet quality. Good diet quality was observed more in older adults (≥65 years old) than in emerging (18–24 years old) or young adults (25–44 years old), regardless of mental status.

Association Between Dietary Inflammatory Index and Mental Health: A Systematic Review and Dose-Response Meta-Analysis

Objective: We aimed to systematically evaluate the association between Dietary Inflammatory Index (DII) and mental health.

Methods: We searched PubMed, Embase, and Web of Science from their inception to December 31, 2020. Categorical meta-analysis and dose–response meta-analysis were performed to evaluate the association between DII and mental health.

Results: A total of 16 studies were included in this meta-analysis. Compared with the lowest DII category, the highest category was significantly associated with a variety of mental health outcomes, with the following pooled odds ratios (ORs) and 95% confidence intervals (95% CIs): 1.28 (1.17–1.39) for symptoms of depression, 1.27 (1.08–1.49) for symptoms of anxiety, 1.85 (1.43–2.40) for distress, and 4.27 (1.27–14.35) for schizophrenia. Furthermore, there was a linear dose–response relationship between DII and symptoms of depression in that a 1-unit increment in DII was associated with an increased risk of 6% for symptoms of depression (OR: 1.06, 95% CI: 1.03–1.19).

Conclusion: The present study indicates that more pro-inflammatory diet, as estimated by the higher DII score, is associated with symptoms of mental disorder. It may be of clinical and public health significance regarding the development of novel nutritional psychiatry approaches to promote good mental health.

Changes in dietary inflammatory potential predict changes in sleep quality metrics, but not sleep duration

STUDY OBJECTIVES

Non-pharmacological sleep interventions may improve sleep profiles without the side-effects observed with many pharmacological sleep aids. The objective of this research was to examine the association between sleep and inflammation and to examine how changes in dietary inflammatory potential influence changes in sleep.

METHODS

The Inflammation Management Intervention Study (IMAGINE), which was a dietary intervention designed to lower inflammation, provided access to 24-h dietary recalls (24HR), objectively measured sleep using SensewearTM armbands, and a range of self-reported demographics, health histories, lifestyle behaviors, psychosocial metrics, anthropometric measurements, and inflammatory biomarkers. Dietary Inflammatory Index® (DII®) scores were calculated from three unannounced 24HR-derived estimated intakes of whole foods and micro and macronutrients over a 2-week period at baseline and post-intervention (i.e. month 3). Statistical analyses primarily utilized linear regression.

RESULTS

At baseline, for every 1-min increase in sleep onset latency, tumor necrosis factor-α increased by 0.015 pg/mL (±0.008, p = 0.05). Every one-percentage increase in sleep efficiency was associated with decreased C-reactive protein (CRP) of -0.088 mg/L (±0.032, p = 0.01). Every 1-min increase in wake-after-sleep-onset (WASO) increased both CRP and interleukin-6. Compared to participants with pro-inflammatory DII changes over 3 months, those with anti-inflammatory changes decreased WASO (0 vs. -25 min, respectively, p < 0.01) and improved sleep efficiency (-2.1% vs. +2.6%, respectively, p = 0.04).

CONCLUSIONS

Non-pharmacological treatments, such as anti-inflammatory diets, may improve sleep in some adults. Future research involving dietary treatments to improve sleep should not only focus on the general population, but also in those commonly experiencing co-morbid sleep complaints.

CLINICAL TRIAL INFORMATION

NCT02382458.

Are depressive disorders caused by psychosocial stressors at work? A systematic review with metaanalysis

In the last decade, many studies have examined associations between poor psychosocial work environment and depression. We aimed to assess the evidence for a causal association between psychosocial factors at work and depressive disorders. We conducted a systematic literature search from 1980 to March 2019. For all exposures other than night and shift work and long working hours, we limited our selection of studies to those with a longitudinal design. We extracted available risk estimates for each of 19 psychosocial exposures, from which we calculated summary risk estimates with 95% confidence intervals (PROSPERO, identifier CRD42019130266). 54 studies were included, addressing 19 exposures and 11 different measures of depression. Only data on depressive episodes were sufficient for evaluation. Heterogeneity of exposure definitions and ascertainment, outcome measures, risk parameterization and effect contrasts limited the validity of meta-analyses. Summary risk estimates were above unity for all but one exposure, and below 1.60 for all but another. Outcome measures were liable to high rates of false positives, control of relevant confounding was mostly inadequate, and common method bias was likely in a large proportion of studies. The combination of resulting biases is likely to have inflated observed effect estimates. When statistical uncertainties and the potential for bias and confounding are taken into account, it is not possible to conclude with confidence that any of the psychosocial exposures at work included in this review is either likely or unlikely to cause depressive episodes or recurrent depressive disorders.

Dietary inflammatory index (DII®) and the risk of depression symptoms in adults

BACKGROUND & AIMS

Findings from observational studies investigating the association between Dietary Inflammatory Index (DII®) scores and depression symptoms (DepS) are inconsistent. This study aims to assess the association between energy-adjusted DII (E-DII™) and DepS using the North West Adelaide Health Study (NWAHS) cohort as well as update a previous meta-analysis.

METHODS

A total of 1743 (mean ± SD age: 56.6 ± 13.6 years, 51% female) study participants from NWAHS were included in the cross-sectional study and 859 (mean ± SD age: 58.4 ± 12.1 years, 52.6% female) in the longitudinal analyses. The Center for Epidemiological Studies Depression Scale (CES-D) was used for the measurement of DepS. E-DII scores were calculated from the dietary data collected using a validated food frequency questionnaire (FFQ). Data from two stages [Stage 3 (2008-10) and North West 15 (NW15) (2015)] were used. Log- and negative binomial regression were used to assess the association between quartiles of E-DII and DepS. A recent meta-analysis was updated by including 12 publications (six cross-sectional and six cohort studies) on the association between DII and DepS.

RESULTS

In the cross-sectional analysis, a higher E-DII score (i.e., more pro-inflammatory diet) was associated with a 79% increase in odds of reporting DepS [OR_Quartile4vs1: 1.79; 95% CI: 1.14-2.81; p = 0.01; p for trend (p_trend) = 0.03]. Males with higher E-DII had a more than two-fold higher odds of DepS (OR_Quartile4vs1: 2.27; 95% CI: 1.02-5.06; p = 0.045; p_trend = 0.09). Females with higher E-DII had an 81% increase in odds of DepS (OR_Quartile4vs1: 1.81; 95% CI: 1.01-3.26; p = 0.046; p_trend = 0.07). These associations were consistent in the longitudinal analysis. Comparing highest to lowest quintiles of E-DII, the updated meta-analysis showed that a pro-inflammatory diet is associated with a 45% increase in odds of having DepS (OR: 1.45; 95% CI: 1.20-1.74; p < 0.01) with higher odds in females (OR: 1.53; 95% CI: 1.16-2.01; p = 0.01) compared to their male counterparts (OR: 1.29; 95% CI: 0.98-1.69; p = 0.15).

CONCLUSION

The data from the NWAHS and the updated meta-analysis of observational studies provide further evidence that a pro-inflammatory diet is positively associated with increased risk of DepS. These findings support the current recommendation on consuming a less inflammatory diet to improve DepS.

The Preoperative Dietary Inflammatory Index Predicts Changes in Cardiometabolic Risk Factors After 12 Months of Roux-en-Y Gastric Bypass

BACKGROUND

The objective of this study was to evaluate Dietary Inflammatory Index (DII®) in the preoperative period as well as 3 and 12 months post-surgery and its association with cardiometabolic risk factors after RYGB.

MATERIALS AND METHODS

This is a prospective cohort study of 50 patients (both sexes) who underwent RYGB. All data were collected in 3 phases: before surgery, 3, and 12 months post-surgery. To calculate DII scores, we utilized mean nutrients from three 24-h recalls at each time point.

RESULTS

The patients had median age of 39.1 ± 7.9 years (70% women). Mean preoperative DII® score of 0.39 ± 1.49 was slightly pro-inflammatory. Mean DII score reduced to - 1.52 ± 1.27 after 3 months post-surgery and was classified anti-inflammatory. This value rebounded to - 0.88 ± 1.49 at 12 months but was still anti-inflammatory. From the adjusted linear regression analysis, we observed that preoperative DII score was statistically associated with variations in neck circumference (β = - 0.50; p = 0.03), waist-hip ratio (β = 0.01; p = 0.02), total cholesterol (β = 6.47; p = 0.002), and LDL cholesterol (β = 6.42; p = 0.001) after 12 months post-surgery. Changes in DII® at 3 and 12 months were not associated with changes in cardiometabolic risk factors.

CONCLUSION

We observe significant changes in the inflammation potential of diet after 3 and 12 months of RYGB. Patients with higher preoperative E-DII scores have a greater metabolic improvement after 12 months of surgery.

Assessing dietary and lifestyle risk behaviours and their associations with disease comorbidities among patients with depression: A case-control study from Bahrain

OBJECTIVES

In Western populations, patients with depression die 10-25 years prematurely compared to controls, mainly due to lifestyle-related diseases. Tobacco smoking, excessive alcohol intake, poor diets and physical inactivity are among the major contributors to disease comorbidities. The objective of this research is to assess the dietary and lifestyle behaviours for Bahraini patients with depression and to determine their associations with different medical comorbidities.

METHODS

A case-control study was conducted from March to December 2019. A sample of 96 diagnosed patients with depression was recruited from the Psychiatric Hospital/Bahrain, and 96 age- and sex-matched controls were recruited from primary health centres. Assessment of anthropometrics, dietary and alcohol intakes, tobacco smoking and physical activity levels were undertaken for both cases and controls. National electronic medical records were reviewed retrospectively for medical comorbidities for the recruited cases. Logistic regression analysis was used to identify associations between lifestyle behaviours and medical comorbidities after controlling for confounding factors.

RESULTS

Patients with depression reported higher intakes of energy and energy-yielding macronutrients (e.g., carbohydrates, protein, and fat); three-fold higher rates of tobacco smoking; and significantly lower levels of physical activity. Cases appeared to be at a doubled risk for developing obesity, diabetes type 2, hypertension, and musculoskeletal disorders. The risk for cardiovascular problems was similar for cases and controls.

CONCLUSIONS

Poor dietary intakes, increased prevalence of smoking, and low levels of physical activity were evident in patients with depression in Bahrain; these factors were associated with some medical comorbidities.

Examining Regional Differences of Dietary Inflammatory Index and Its Association with Depression and Depressive Symptoms in Korean Adults

The relationship between the dietary inflammatory index (DII^®) and depression and depressive symptoms in South Korean adults remains unclear. This study aimed to examine the overall relationship between the DII and depression in South Korea and to evaluate the association between the DII and depressive symptoms and depression across regions among Korean adults aged ≥19 years. A total of 15,929 study participants were selected from the Korea National Health and Nutrition Examination Survey (KNHANES) 2014–2017. Energy-adjusted (E-DII) scores were calculated using 24-h dietary recall data. Depression and depressive symptoms were measured on the basis of the Korean version of the Patient Health Questionnaire 9-item scale, a doctor’s diagnosis of depression, and self-reported depressive symptom-related questionnaire. Overall, 4.2% of the participants had depression, with notable gender differences (i.e., 2.4% in men and 6.2% in women). Korean adults residing in the Capital area, Chungcheong-do and Jeju-do, and with diets in the highest tertile of the E-DII (most pro-inflammatory diet) had significantly increased odds of having depression and depressive symptoms compared with those in the lowest tertile of the E-DII (most anti-inflammatory diet) after controlling for covariates (adjusted odds ratio (AOR): 1.44, 95% confidence interval (CI): 1.04–1.99; AOR 2.97, 95% CI 1.36–6.52; AOR 4.06, 95% CI 1.56–10.53, respectively). No association between the E-DII and depression/depressive symptoms was found in other regions of South Korea. A pro-inflammatory diet is associated with greater odds of depression and depressive symptoms, with distinct regional differences. The present study provides evidence regarding existing regional differences in the association of the E-DII with depression and depressive symptoms.

The relationship between dietary inflammatory index and psychosomatic complaints profiles: results from SEPAHAN cross-sectional study

Background

Although the dietary inflammatory index (DII) has been evaluated in relation to psychological disorders risk, the association between DII and psychosomatic complaints is unclear. This study aimed to determine the association between DII, as a proxy measure of the inflammatory potential of the diet, and psychosomatic complaints.

Methods

This cross-sectional study included 2818 people from the general population, aged 19 to 69 years, of Isfahan province in Iran. Dietary intake was assessed using a validated dish-based food-frequency questionnaire. Psychosomatic complaints were assessed using a self-administered validated Persian questionnaire. Twenty-seven nutrients or foods were included in the calculation of DII. Each of them received a score based on their inflammatory ability, thus, a higher DII score indicated a more pro-inflammatory diet. The risk of being in the top median of a psychosomatic complaints profile across the tertiles of DII was assessed using logistic regression.

Results

Four psychosomatic complaints profiles (psychological, gastrointestinal, neuro-skeletal and pharyngeal- respiratory) were identified. After controlling for potential confounders, individuals in the top tertile of DII had higher odds for experiencing high somatic complaints scores for the psychological (odds ratio (OR) = 1.44, 95% confidence interval (CI): 1.10, 1.89; P trend = 0.009), gastrointestinal (OR = 1.22, 95% CI: 0.99, 1.75; P = 0.058) or neuro-skeletal (OR = 1.56, 95% CI: 1.10, 2.22; P = 0.013) profile. The association for pharyngeal-respiratory complaints did not remain significant after adjustment for stressful life events, medical condition, and anti-psychotropic medicine use.

Conclusion

The significant positive link between DII and the various psychosomatic complaints profiles suggests that a diet with anti-inflammatory potential might be favourably related to psychosomatic complaints. Further studies, particularly clinical trials and longitudinal studies, are warranted to investigate the inflammatory potential of diet in relation to psychosomatic complaints.

Increased Dietary Inflammatory Index Is Associated with Schizophrenia: Results of a Case-Control Study from Bahrain

BACKGROUND

Several studies have indicated that chronic low-grade inflammation is associated with the development of schizophrenia. Given the role of diet in modulating inflammatory markers, excessive caloric intake and increased consumption of pro-inflammatory components such as calorie-dense, nutrient-sparse foods may contribute toward increased rates of schizophrenia. This study aimed to examine the association between dietary inflammation, as measured by the dietary inflammatory index (DII^®), and schizophrenia.

METHODS

A total of 120 cases attending the out-patient department in the Psychiatric Hospital/Bahrain were recruited, along with 120 healthy controls matched on age and sex. The energy-adjusted DII (E-DII) was computed based on dietary intake assessed using a comprehensive food frequency questionnaire (FFQ). Logistic regression was used to estimate odds ratios and 95% confidence intervals, adjusting for potential confounders including age, sex, body mass index, education, employment, diabetes, hypertension, and cardiovascular disease with E-DII expressed both as a continuous variable and categorized as quartiles.

RESULTS

The mean E-DII score for the entire sample was 1.79 ± 1.52, indicating a generally pro-inflammatory diet. The cases with schizophrenia appeared to have a higher E-DII score compared to controls: 1.99 ± 1.39 vs. 1.60 ± 1.38, respectively (p = 0.009). For every one unit increase in the E-DII score, the odds of having schizophrenia increased by 62% (OR 1.62; 95% CI 1.17-2.26). Similarly, increased risk was observed when the E-DII was used as quartiles, with participants in most pro-inflammatory quartile 4 being nearly 6 times more likely to be schizophrenic than participants in the most anti-inflammatory group quartile 1 (OR 5.96; 1.74-20.38; p-trend = 0.01).

CONCLUSIONS

The data suggest that a pro-inflammatory diet, as indicated by increasing E-DII score, is associated with schizophrenia. This is the first study to examine the association between the DII and schizophrenia in a Middle Eastern population. Although these results are consistent with findings from research conducted in depression, additional studies are required before generalizing the findings to other populations.

The Inflammatory Potential of the Diet is Directly Associated with Incident Depressive Symptoms Among French Adults

BACKGROUND

Low-grade chronic inflammation has been suggested to play a substantial role in the etiology of depression; however, studies on the prospective association between the inflammatory potential of the diet and depression are limited.

OBJECTIVE

The aim of this study was to investigate the association between the inflammatory potential of the diet (measured using the Alternate Dietary Inflammatory Index, ADII) and incident depressive symptoms. We also tested the potential modulating effect of sex, age, BMI, and lifestyle indicators.

METHODS

The study sample consisted of 26,730 participants (aged 18-86 y) from the NutriNet-Santé study. Baseline ADII was computed using repeated 24-h dietary records collected during the first 2 y of the follow-up. Incident cases of depressive symptoms were defined by a Center for Epidemiologic Studies Depression scale ≥17 for men and ≥23 for women at least once during follow-up. HR and 95% CI were estimated using multivariable Cox proportional hazards models.

RESULTS

A total of 2221 incident cases of depressive symptoms were identified over a mean follow-up of 5.4 y. After accounting for a wide range of potential confounders, the highest quartile of the ADII was associated with a 15% (95% CI: 2, 31) increase in the risk of depressive symptoms compared with the lowest quartile. In the stratified analyses, associations were statistically significant only among women (HRquartile4 vs. quartile1: 1.19; 95% CI: 1.02, 1.37), middle-age adults (HRquartile4 vs. quartile1: 1.16; 95% CI: 1.00, 1.35), and participants with a BMI ≥25 (HRquartile4 vs. quartile1: 1.29; 95% CI: 1.04, 1.60).

CONCLUSIONS

Overall, a proinflammatory diet was associated with a higher risk of depressive symptoms, especially among women, middle-age adults, and participants with overweight or obesity. These findings contribute to the increasing scientific evidence showing a detrimental role of the proinflammatory diet. The NutriNet-Santé study is registered at clinicaltrials.gov as NCT03335644.

Healthy dietary indices and risk of depressive outcomes: a systematic review and meta-analysis of observational studies

With depression being the psychiatric disorder incurring the largest societal costs in developed countries, there is a need to gather evidence on the role of nutrition in depression, to help develop recommendations and guide future psychiatric health care. The aim of this systematic review was to synthesize the link between diet quality, measured using a range of predefined indices, and depressive outcomes. Medline, Embase and PsychInfo were searched up to 31st May 2018 for studies that examined adherence to a healthy diet in relation to depressive symptoms or clinical depression. Where possible, estimates were pooled using random effect meta-analysis with stratification by observational study design and dietary score. A total of 20 longitudinal and 21 cross-sectional studies were included. These studies utilized an array of dietary measures, including: different measures of adherence to the Mediterranean diet, the Healthy Eating Index (HEI) and Alternative HEI (AHEI), the Dietary Approaches to Stop Hypertension, and the Dietary Inflammatory Index. The most compelling evidence was found for the Mediterranean diet and incident depression, with a combined relative risk estimate of highest vs. lowest adherence category from four longitudinal studies of 0.67 (95% CI 0.55-0.82). A lower Dietary Inflammatory Index was also associated with lower depression incidence in four longitudinal studies (relative risk 0.76; 95% CI: 0.63-0.92). There were fewer longitudinal studies using other indices, but they and cross-sectional evidence also suggest an inverse association between healthy diet and depression (e.g., relative risk 0.65; 95% CI 0.50-0.84 for HEI/AHEI). To conclude, adhering to a healthy diet, in particular a traditional Mediterranean diet, or avoiding a pro-inflammatory diet appears to confer some protection against depression in observational studies. This provides a reasonable evidence base to assess the role of dietary interventions to prevent depression. This systematic review was registered in the PROSPERO International Prospective Register of Systematic Reviews under the number CRD42017080579.

What Is the Role of Dietary Inflammation in Severe Mental Illness? A Review of Observational and Experimental Findings

Severe mental illnesses (SMI), including major depressive disorder, bipolar disorder, and schizophrenia, are associated with increased inflammation. Given diet's role in modulating inflammatory processes, excessive calorie-dense, nutrient-deficient processed food intake may contribute toward the heightened inflammation observed in SMI. This review assesses the evidence from observational and experimental studies to investigate how diet may affect physical and mental health outcomes in SMI through inflammation-related pathways. Cross-sectional studies indicate that individuals with SMI, particularly schizophrenia, consume more pro-inflammatory foods and fewer anti-inflammatory nutrients than the general population. Cohort studies indicate that high levels of dietary inflammation are associated with increased risk of developing depression, but there is currently a lack of evidence for schizophrenia or bipolar disorder. Randomized controlled trials show that dietary interventions improve symptoms of depression, but none have tested the extent to which these benefits are due to changes in inflammation. This review summarizes evidence on dietary inflammation in SMI, explores the directionality of these links, and discusses the potential use of targeted nutritional interventions for improving psychological well-being and physical health outcomes in SMI. Establishing the extent to which diet explains elevated levels of inflammatory markers observed in SMI is a priority for future research.

Shift work and mental health: a systematic review and meta-analysis

BACKGROUND

Shift work is common. However, research findings are mixed regarding the impact of shift work on mental health. This systematic review sought to provide a comprehensive summary of existing research examining the association between different types of shift work and mental health. The review included large-scale, non-occupation-specific research.

METHODS

Four electronic databases PubMed, PsycINFO, Web of Science and SCOPUS were searched to identify studies that reported on the statistical association between shift work and mental health and that used population-based samples. Two reviewers extracted information about study characteristics and data on the association between shift work and mental health. A meta-analysis was performed for longitudinal studies adopting a 'broad binary' measure of shift work.

RESULTS

Thirty-three studies were included in the final review-10 cross-sectional studies, 22 longitudinal studies, and 1 study that included both. Findings were grouped based on whether the measure of shift work focussed on: (1) night/evening work, (2) weekend work, (3) irregular/unpredictable work schedule, or (4) a broad binary measure. There was a reasonable level of evidence that overall, when a broad binary measure was adopted, shift work was associated with poorer mental health-this finding was supported by the meta-analysis results. There was also some evidence that irregular/unpredictable work was associated with poorer mental health. There was less evidence for night/evening and minimal evidence for weekend work. Inconsistencies in study methodology, limited contrasting and combining the results.

CONCLUSIONS

The association between shift work and mental health is different across types of shift work. The evidence is strongest for a broad binary, general measure of shift work and for irregular or unpredictable shift work. There is a need for continued research that adopts consistent and clear measures of shift work.

Perspective: The Dietary Inflammatory Index (DII)-Lessons Learned, Improvements Made, and Future Directions

The literature on the role of inflammation in health has grown exponentially over the past several decades. Paralleling this growth has been an equally intense focus on the role of diet in modulating inflammation, with a doubling in the size of the literature approximately every 4 y. The Dietary Inflammatory Index (DII) was developed to provide a quantitative means for assessing the role of diet in relation to health outcomes ranging from blood concentrations of inflammatory cytokines to chronic diseases. Based on literature from a variety of different study designs ranging from cell culture to observational and experimental studies in humans, the DII was designed to be universally applicable across all human studies with adequate dietary assessment. Over the past 4 y, the DII has been used in >200 studies and forms the basis for 12 meta-analyses. In the process of conducting this work, lessons were learned with regard to methodologic issues related to total energy and nutrient intake and energy and nutrient densities. Accordingly, refinements to the original algorithm have been made. In this article we discuss these improvements and observations that we made with regard to misuse and misinterpretation of the DII and provide suggestions for future developments.

Dietary Inflammatory Potential and the Risk of Incident Depression in Adults: A Systematic Review

Diet is proposed to have a stimulatory or preventative influence on mental health and the risk of depressive symptoms, given that the diet can have either a pro- or an anti-inflammatory effect. This study aimed to collate the relation between dietary inflammatory potential and the risk of depression. PubMed, Google Scholar, ScienceDirect, and Scopus databases, as well as Google were searched for articles published at any date until May 2018. Original English-language articles involving human participants and studies that investigated the association between dietary inflammatory potential and the risk of developing depression were included. Duplicated and irrelevant reports were screened out and data were extracted during critical analysis. Our search method initially identified 173 articles, of which 48 remained after duplicates had been removed. Thirteen articles were screened and identified as being relevant to the study topic. After critical analysis, 12 articles were included in the final analysis. All of the articles but 1 reported that higher dietary inflammatory index (DII) is associated with a higher risk of developing depression. Three studies indicated that DII was positively correlated with circulating inflammatory markers; however, in these studies increased concentrations of circulating inflammatory markers did not predict the diet-depression relation. Low literacy, unhealthy lifestyle, nutritional status, marital status, and age were potent contributory factors to whether or not a diet with inflammatory potential was consumed. These findings support the hypothesis that the DII is an appropriate tool for measuring dietary inflammatory potential, and reinforce the role of diets with inflammatory potential in the pathophysiology of depression.

An anti-inflammatory diet as a potential intervention for depressive disorders: A systematic review and meta-analysis

BACKGROUND & AIMS

There is a large body of evidence which supports the role of inflammation in the pathophysiology of mental health disorders, including depression. Dietary patterns have been shown to modulate the inflammatory state, thus highlighting their potential as a therapeutic tool in disorders with an inflammatory basis. Here we conduct a systematic review and meta-analysis of current literature addressing whether there is a link between the inflammatory potential of a diet and risk of depression or depressive symptoms.

METHODS

A systematic literature search was performed to identify studies that reported an association between the inflammatory potential of the diet and risk of depressive symptoms or diagnosis of depression. Random effect models were used to meta-analyse effect sizes. Quality assessment, publication bias, sensitivity and subgroup analyses were also performed.

RESULTS

Eleven studies, with a total of 101,950 participants at baseline (age range: 16-72 years old), were eligible for review. A significant association between a pro-inflammatory diet and increased risk of depression diagnosis or symptoms was evident, relative to those on an anti-inflammatory diet (OR: 1.40, 95% confidence intervals: 1.21-1.62, P < 0.001). No publication bias was detected; however, some study heterogeneity was evident (I² = 63%, P < 0.001). Subgroup analyses suggested the main source of study heterogeneity was the study design (cross-sectional or longitudinal) and the effect measure used (odds ratio, hazard ratio or relative risk).

CONCLUSION

These results provide an association between pro-inflammatory diet and risk of depression. Thus, adopting an anti-inflammatory diet may be an effective intervention or preventative means of reducing depression risk and symptoms.

Association between dietary inflammatory index and psychological profile in adults

BACKGROUND & AIMS

Limited data are available on the association of inflammatory potential of the diet and odds of psychological disorders. We investigated the association between adherence to a pro-inflammatory diet, as measured by Dietary Inflammatory Index (DII), and odds of psychological disorders.

METHODS

In this cross-sectional study, dietary intakes of 3363 Iranian adult participants were collected using a validated Dish-based 106-item Semi-quantitative Food Frequency Questionnaire (DS-FFQ). DII score was calculated based on participants' dietary intakes obtained from DS-FFQ. The Iranian validated version of Hospital Anxiety and Depression Scale (HADS) and General Health Questionnaire (GHQ) was used to assess psychological disorders. For depression and anxiety, scores of 8 or more on either subscale were considered as psychological disorders and scores of 0-7 were defined as "normal". In terms of psychological distress, the score of 4 or more was defined as psychological distress.

RESULTS

Overall, 28% (n = 943) of study participants had depression, 13.3% (n = 448) were affected by anxiety and 22.6% (n = 760) by psychological distress. After controlling for potential confounders, individuals in the highest quintile of DII score had higher scores of depression (6.56 ± 0.16 vs. 5.48 ± 0.16; P < 0.001), anxiety (3.85 ± 0.17 vs. 3.09 ± 0.17; P = 0.006), and psychological distress (2.42 ± 0.13 vs. 1.77 ± 0.13; P = 0.001), compared with those in the lowest quintile. Participants in the top quintile of DII score had greater odds of depression (OR: 1.84, 95% CI: 1.30-2.60), anxiety (OR: 1.69, 95% CI: 1.07-2.67), and psychological distress (OR: 1.72, 95% CI: 1.20-2.46) than those in the bottom quintile.

CONCLUSIONS

We found that adherence to a pro-inflammatory diet was positively associated with psychological disorders.

Dietary inflammatory index and depression: a meta-analysis

OBJECTIVE

The purpose of the present meta-analysis was to evaluate the association between the inflammatory potential of diet, determined by the dietary inflammatory index (DII®) score, and depression.

DESIGN

Systematic review and meta-analysis.

SETTING

A comprehensive literature search was conducted in PubMed, Web of Science and EMBASE databases up to August 2018. All observational studies that examined the association of the DII score with depression/depressive symptoms were included.

SUBJECTS

Four prospective cohorts and two cross-sectional studies enrolling a total of 49 584 subjects.

RESULTS

Overall, individuals in the highest DII v. the lowest DII category had a 23 % higher risk of depression (risk ratio (RR)=1·23; 95 % CI 1·12, 1·35). When stratified by study design, the pooled RR was 1·25 (95 % CI 1·12, 1·40) for the prospective cohort studies and 1·16 (95 % CI 0·96, 1·41) for the cross-sectional studies. Gender-specific analysis showed that this association was observed in women (RR=1·25; 95 % CI 1·09, 1·42) but was not statistically significant in men (RR=1·15; 95 % CI 0·83, 1·59).

CONCLUSIONS

The meta-analysis suggests that pro-inflammatory diet estimated by a higher DII score is independently associated with an increased risk of depression, particularly in women. However, more well-designed studies are needed to evaluate whether an anti-inflammatory diet can reduce the risk of depression.

Association between the dietary inflammatory index and common mental health disorders profile scores

BACKGROUND & AIMS

The association between diet and mental health disorders might be mediated by inflammatory properties of the diet. We evaluated the association between the dietary inflammatory index (DII) and the risk of a worsened mental health disorders profile.

METHODS

A total of 3363 Iranian adults were included in this cross-sectional study. A mental health disorders profile score was calculated using regression analysis, within the framework of factor analysis, based on anxiety, depression and psychological distress, with a higher scores indicating greater severity of mental problems. Dietary intakes were assessed using a validated dish-based food frequency questionnaire (DFQ). Twenty-seven macro- and micro-nutrients, onions, tea and caffeine were included in the calculation of DII. Each of them received a score based on their inflammatory ability, thus, a greater DII indicated a more pro-inflammatory diet. The odds of being in the highest tertile of mental health disorders profile across the tertiles of DII was assessed using multinomial logistic regression.

RESULTS

Either in the crude or fully-adjusted multinomial logistic regression models, participants in the lowest tertile of DII had a lower risk for being in the top tertile of mental health disorders profile (adjusted model: OR: 0.45; 95% CI: 0.33, 0.60; P trend<0.001). In a stratified analysis by sex, similar findings were observed in both genders, although there was only a trend for the associations to be significant in men (men: OR: 0.53; 95% CI: 0.31, 0.90; P trend = 0.070; women: OR: 0.40; 95% CI: 0.27, 0.58; P trend<0.0001).

CONCLUSIONS

Our findings suggest a direct association between the pro-inflammatory properties of the diet and an increased risk of higher mental health disorders profile scores. Prospective dietary intervention studies and observational prospective cohorts are required to confirm these findings.

Association between the Dietary Inflammatory Index (DII) and urinary enterolignans and C-reactive protein from the National Health and Nutrition Examination Survey-2003-2008

BACKGROUND

Enterolignans are important biomarkers of microbiota diversity, with higher levels indicating greater diversity. Diet and inflammation have been shown to play a role in maintaining microbiota diversity. This study examined whether inflammatory potential of diet, as measured by the Dietary Inflammatory Index (DII^®) has an impact on levels of urinary enterolignans in the National Health and Nutrition Examination Survey (NHANES) 2003-2008. We also carried out construct validation of the DII with C-reactive protein (CRP).

METHODS

Data came from NHANES 2003-2008. Enterolignans [enterodiol (END) and enterolactone (ENL)] and CRP were assayed from urine and serum specimens, respectively. Energy-adjusted DII (E-DII) scores were calculated from food intakes assessed using 24-h dietary recalls and expressed per 1000 calories consumed. Associations were examined using survey-based multivariable linear and logistic regression for enterolignans, and logistic regression for CRP.

RESULTS

After multivariable adjustment, higher E-DII scores (i.e., indicating a relatively more pro-inflammatory diet) were associated with lower levels of creatinine-normalized END [beta coefficient (b)_{DIIquartile4vs1} = - 1.22; 95% CI = - 0.69, - 1.74; P_trend ≤ 0.001] and ENL (b_{DIIquartile4vs1} = - 7.80; 95% CI = - 5.33, - 10.26; P_trend ≤ 0.001). A positive association was also observed when enterolignans were dichotomized based on the cut-off of the 75th percentile value. In this same sample, the E-DII also was associated with CRP ≥ 3 mg/l (OR_{DIIcontinuous} = 1.12; 95% CI 1.05, 1.19).

CONCLUSION

In these NHANES data, there was an association between E-DII score and enterolignans. This study also provided construct validation of the E-DII using CRP in a nationally representative sample. The results indicate that dietary inflammatory potential is associated with urinary enterolignans, a potential marker for microbiota diversity. However, studies are required to understand the direct association between DII and microbiota.

A Pro-Inflammatory Diet Is Associated With an Increased Odds of Depression Symptoms Among Iranian Female Adolescents: A Cross-Sectional Study

Background: The relation between dietary inflammation and risk of depression has not been widely explored. We examined the association between the inflammatory effect of the diet and the odds of depression among Iranian female adolescents. Methods: Using a stratified cluster sampling technique, 300 female adolescents aged 15-18 years were recruited from schools in Tehran between years 2014-2015. Depression was assessed using the Depression, Anxiety and Stress Scale (DASS)- a 21-point scale. The dietary inflammatory index (DII®) was used to evaluate the inflammatory potential of the diet. Dietary intake was assessed using a validated food frequency questionnaire. In addition to descriptive statistics, multivariable linear and logistic regression were used to calculate confounder-adjusted beta estimates and odds ratios. Results: In total, 88 females (30%) had at least a moderate level of depressive symptoms (DASS > 6). Females with the most pro-inflammatory diet had higher DASS depression score (β = 1.67; 95% CI = 0.03, 3.31) and were at 3.96 (95% CI = 1.12, 13.97) times higher odds of having at least moderate depressive symptoms, compared to females with the least anti-inflammatory diets. Conclusion: These data suggest that Iranian adolescent females eating a pro-inflammatory diet, as indicated by higher DII scores, had greater odds of having at least moderate depressive symptoms.