Long-term associations between inflammatory dietary scores in relation to long-term C-reactive protein status measured 12 years later: findings from the Supplémentation en Vitamines et Minéraux Antioxydants (SU.VI.MAX) cohort

Dietary inflammatory potential and arterial stiffness in a French cohort: Insights from the STANISLAS study

BACKGROUND AND AIMS

Chronic inflammation plays a key role in arterial stiffness pathogenesis. Dietary components can display anti- or pro-inflammatory properties. Nonetheless, the association between the diet's overall inflammatory potential and arterial stiffness is unclear. This study aimed to assess the association between the diet's overall inflammatory potential and arterial stiffness assessed by carotid-femoral pulse wave velocity (cfPWV).

METHODS AND RESULTS

This cross-sectional study included 1307 participants from the STANISLAS family cohort study. Dietary data were collected using a validated food frequency questionnaire. The adapted dietary inflammatory index (ADII) score was calculated to assess the inflammatory potential of the participants' diet. The association of ADII score quartile with cfPWV was assessed using IPW-weighted linear mixed models with random family effect. The median (Q1-Q3) ADII score was 0.45 (-1.57, 2.04). Participants exhibiting higher ADII scores demonstrated elevated energy intake, dietary saturated fat, and ultra-processed foods. Conversely, individuals with lower ADII scores exhibited higher vitamins and omega intakes, and a higher diet quality, as assessed by the DASH score. Despite these observations from the descriptive analyses, ADII score quartiles were not significantly associated with cfPWV (β(95% CI) were 0.01 (-0.02,0.04) for Q2, 0.02 (-0.01,0.05) for Q3, and 0.02 (-0.01,0.05) for Q4 compared to Q1).

CONCLUSION

In this cross-sectional study, participants had a relatively modest consumption of pro-inflammatory foods, no substantial associations were observed between the diet inflammatory potential and arterial stiffness. Further longitudinal studies in larger cohorts are needed to better understand the link between inflammatory diet and arterial stiffness.

Nutritional interventions as modulators of the disease activity for idiopathic inflammatory myopathies: a scoping review

Idiopathic inflammatory myopathies (IIMs) are chronic, autoimmune connective tissue diseases associated with significant morbidity and disability. Nutrients can activate the immune system and contribute to chronic low-grade inflammation (LGI). Chronic muscle inflammation leads to imbalanced pro-inflammatory and anti-inflammatory cytokines, causing inadequate nutrition, weight loss and muscle weakness during a negative cycle. Owing to its potential to modulate LGI in various diseases, the Mediterranean diet (Med Diet) has been extensively studied. This scoping review explores the nutritional implications and recommendations of the Med Diet as a treatment for immune-mediated diseases, focusing on the gaps in IIM nutritional interventions. A comprehensive literature search of the MEDLINE and EBSCO databases between September 2018 and December 2022 was performed. We identified that the Med Diet and its specific components, such as omega-3 (nω3) fatty acids, vitamin D and antioxidants, play a role in the dietary treatment of connective tissue-related autoimmune diseases. Nutritional interventions have demonstrated potential for modulating disease activity and warrant further exploration of IIMs through experimental studies. This review introduces a dietary therapeutic approach using the Med Diet and related compounds to regulate chronic inflammatory processes in IIMs. However, further clinical studies are required to evaluate the efficacy of the Med Diet in patients with IIMs. Emphasising a clinical-nutritional approach, this study encourages future research on the anti-inflammatory effects of the Med Diet on IIMs. This review highlights potential insights for managing and treating these conditions using a holistic approach.

Meta-analysis of the association between dietary inflammation index and C-reactive protein level

BACKGROUND

There have been various clinical studies on the effect of dietary inflammatory index (DII) on circulating inflammatory biomarkers, but the findings from these are contradictory. The aim of the present study was to clarify any association.

METHODS

The PubMed, Embase, Web of Science and Cochrane Library database were searched for relevant studies from inception February 2021. There were no language restrictions. Two investigators independently selected eligible studies. Measures of association were pooled by using an inverse-variance weighted random-effects model. The heterogeneity among studies was examined using the I2 index. Publication bias, sensitivity and subgroup analyses were also performed.

RESULTS

A total of 13 cross-sectional studies were identified, involving 54,813 participants. The adjusted pooled OR of C-reactive protein (CRP) levels for the highest (the most pro-inflammatory diet) versus lowest (the most anti-inflammatory diet) DII categories was 1.25 (95% CI: 1.18-1.32; I2  = 59.4%, P = .002). Subgroup analyses suggested the main source of study heterogeneity was the geographic area (Asia, Europe, or USA) and CRP levels (>3 mg/L or others). This finding was remarkably robust in the sensitivity analysis.

CONCLUSION

The meta-analysis suggests that more pro-inflammatory DII scores were positively associated with CRP, the DII scores can be useful to assess the diet inflammatory properties and its association with low-grade inflammation.

Association between dietary inflammation index and female infertility from National Health and Nutrition Examination Survey: 2013-2018

Objective

To investigate the relationship between dietary inflammatory index (DII) scores and infertility in US adults aged 18 to 45.

Methods

Data were gathered from the 2013-2018 National Health and Nutrition Examination Survey (NHANES). In total, 3496 women were included in the study. To examine the relationship between DII, EDII and infertility, a weighted multivariable logistic regression analysis using continuous factors or categorical variables grouped by quartiles was conducted. Using subgroup analysis stratified based on DII and infertility features, the association between DII and infertility has been further studied. In order to determine whether there was a nonlinear relationship between DII and infertility, restricted cubic spline (RCS) analysis was carried out.

Results

For statistical analysis, a total of 3496 individuals - 367 patients with infertility and 3129 persons without infertility - were included. A multivariable logistic regression study revealed a positive relationship between DII and infertility. A significant difference in subgroup analysis was shown in age group and race, although RCS analysis demonstrated nonlinear relationship between the DII and infertility.

Conclusion

For participants aged 18-45 years, higher DII scores were positively correlated with infertility. In addition, anti-inflammatory diets might improve infertility outcomes.

Association between dietary inflammatory index and Stroke in the US population: evidence from NHANES 1999-2018

BACKGROUND

There is an increasing awareness that diet-related inflammation may have an impact on the stroke. Herein, our goal was to decipher the association of dietary inflammatory index (DII) with stroke in the US general population.

METHODS

We collected the cross-sectional data of 44,019 participants of the National Health and Nutrition Examination Survey (NHANES) 1999-2018. The association of DII with stroke was estimated using weighted multivariate logistic regression, with its nonlinearity being examined by restricted cubic spline (RCS) regression. The least absolute shrinkage and selection operator (LASSO) regression was applied for identifying key stroke-related dietary factors, which was then included in the establishment of a risk prediction nomogram model, with the receiver operating characteristic (ROC) curve being built to evaluate its discriminatory power for stroke.

RESULTS

After confounder adjustment, the adjusted odds ratios (ORs) with 95% confidence intervals (CIs) for stroke across higher DII quartiles were 1.19 (0.94-1.54), 1.46 (1.16-1.84), and 1.87 (1.53-2.29) compared to the lowest quartile, respectively. The RCS curve showed a nonlinear and positive association between DII and stroke. The nomogram model based on key dietary factors identified by LASSO regression displayed a considerable predicative value for stroke, with an area under the curve (AUC) of 79.8% (78.2-80.1%).

CONCLUSIONS

Our study determined a nonlinear and positive association between DII and stroke in the US general population. Given the intrinsic limitations of cross-sectional study design, it is necessary to conduct more research to ensure the causality of such association.

Association between dietary inflammation index and hypertension in participants with different degrees of liver steatosis

BACKGROUND

The prevalence of hypertension (HTN) is higher in patients with non-alcoholic fatty liver disease (NAFLD). Inflammation is the key link between HTN and NAFLD. Systemic inflammation can be dramatically increased by inflammatory diet intake. However, whether controlling the inflammatory diet intake in NAFLD patients could affect the occurrence of HTN still remains unknown. Our aim here is to evaluate the effect of the dietary inflammatory index (DII) on blood pressure in patients with different grades of hepatic steatosis.

MATERIALS AND METHODS

The data were collected from the National Health and Nutrition Examination Survey (NHANES) (2017-2018). DII was calculated based on the data of 24-h dietary recall interviews. The severity of liver steatosis was assessed by a controlled attenuation parameter. Multivariable logistic regression, multivariable linear regression and subgroup analyses were conducted to determine the association between DII and blood pressure in patients with different degrees of hepatic steatosis.

RESULTS

A total of 5449 participants were included in this analysis. In male participants with severe liver steatosis (S3), the highest DII tertile group was more likely to have higher systolic blood pressure (SBP) compared with the lowest tertile group (Tertile1: 128.31(125.31,131.31), Tertile3: 133.12(129.40,136.85), P for trend =0.03551). DII was positively correlated with SBP and the prevalence of HTN in males with hepatic steatosis grade S3 (≥ 67% steatosis) (SBP: P for trend = 0.011, HTN: P for trend = 0.039). Regarding the association of DII with SBP and HTN, the tests for interaction were significant for hepatic steatosis (SBP: interaction for p = 0.0015, HTN: interaction for p = 0.0202).

CONCLUSIONS

In the present study, we demonstrated that DII was a risk factor for increased SBP and the prevalence of HTN in males with severe hepatic steatosis S3, indicating that anti-inflammatory dietary management should be considered in these individuals to reduce the risk of developing HTN.

Construct Validation of the Dietary Inflammatory Index (DII) among Young College-Aged Women

The Dietary Inflammatory Index (DII) is designed to assess the inflammatory potential of the diet. While previous research has utilized DII among college-aged women, no study to date has validated it in this population. We conducted a construct validation of DII among 393 healthy women aged 18-31 years against a robust panel of 14 inflammatory biomarkers, including CRP, IL-1β, IL-4, IL-6, IL-10, and TNF-α, which were used in the development of DII. Three linear regression models were constructed: (1) an age-adjusted model, (2) the most parsimonious model based on likelihood ratio tests, and (3) a fully adjusted model for age, race, body mass index, waist circumference, physical activity, smoking status, and nonsteroidal anti-inflammatory drug use. DII was derived from the Harvard food frequency questionnaire and categorized into quartiles. Consistent with our hypothesis, DII was negatively and significantly associated with back-transformed IL-10 levels, confirming that a more pro-inflammatory diet was associated with lower levels of an anti-inflammatory cytokine (Model 3: Q4 vs. Q1 β = 0.62; 95% CI: 0.42, 0.93; p-trend = 0.04). While validated in other populations, DII may not be a suitable tool for assessing the inflammatory potential of the diet among college-aged women.

Dietary inflammatory index and elevated serum C-reactive protein: A systematic review and meta-analysis

Diet can affect the inflammatory state of the body. Accordingly, the dietary inflammatory index (DII) has been developed to quantify the inflammatory properties of food items. This study sought to investigate the association between dietary inflammation index (DII) and the odds ratio of elevated CRP (E-CRP) through a systematic review and meta-analysis study. The International electronic databases of PubMed, Web of Science (ISI), and Scopus were searched until May 2023 to find related articles. From 719 studies found in the initial search, 14 studies, with a total sample size of 59,941 individuals, were included in the meta-analysis. The calculated pooled odds ratio (OR) of E-CRP in the highest DII category was 1.39 (95% CI: 1.06, 1.14, test for heterogeneity: p = .63, and I 2 = .0%) in comparison with the lowest DII category. Also, the results of this study showed that each unit increase in DII as a continuous variable generally elicited a 10% increase in the odds of E-CRP (OR 1.10, 95% CI 1.06, 1.14, test for heterogeneity: p = .63, and I 2 = .0%). Subgroup meta-analyses showed that there is a higher E-CRP odds ratio for the articles that reported energy-adjusted DII (E-DII) instead of DII, the studies that measured CRP instead of hs-CRP, and the studies that used 24-h recall instead of FFQ as the instrument of dietary intake data collection. Individuals with a higher DII were estimated to have higher chances of developing elevated serum CRP. This value was influenced by factors such as the participants' nationality, instruments of data collection, methods used to measure inflammatory biomarkers, study design, and data adjustments. However, future well-designed studies can help provide a more comprehensive understanding of the inflammatory properties of diet and inflammatory serum biomarkers.

Dietary protein interacts with polygenic risk scores and modulates serum concentrations of C-reactive protein in overweight and obese Malaysian adults

Dietary intake may interact with gene variants and modulate inflammatory status. This study aimed to investigate the combined effect of fat mass and obesity-associated rs9930501, rs9930506, and rs9932754 and beta-2 adrenergic receptor rs1042713 on C-reactive protein (CRP) concentrations using polygenic risk scores (PRS), and modulatory effect of dietary nutrients on these associations. We hypothesized that higher protein intake is associated with lower inflammatory status in individuals genetically predisposed to obesity. PRS was computed as the weighted sum of the risk alleles possessed and stratified into first (0-0.64), second (0.65-3.59), and third (3.60-8.18) tertiles. A total of 128 overweight and obese Malaysian adults were dichotomized into groups of low and elevated inflammatory status (CRP concentrations ≤3 and >3 mg/L, respectively). One-half of the study participants (51%) were found to have elevated inflammatory status. Second- and third-tertile PRS were significantly associated with increased odds of elevated inflammatory status, 7.56 (95% confidence interval [CI], 1.98-28.80; adjusted P = .003) and 3.87 (95% CI, 1.10-13.60; adjusted P = .035), respectively. Individuals in the third-tertile PRS had significantly lower CRP concentrations (4.61 ± 1.3 mg/L vs 9.60 ± 2.6 mg/L, P = .019) when consuming ≥14% energy from protein (with an average of 18.0% ± 2.4%, 43.0% ± 7.7%, and 39.0% ± 8.0% energy from protein, carbohydrate, and fat per day). In conclusion, third-tertile PRS was significantly associated with increased odds of elevated CRP; higher protein intake may alleviate inflammatory status and reduce CRP concentrations systemically in those individuals.

Inflammatory potential of the diet and association with risk of differentiated thyroid cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort

PURPOSE

Chronic inflammation is thought to initiate or promote differentiated thyroid cancer (DTC) and previous studies have shown that diet can modulate this inflammatory process. We aimed to evaluate the association of several dietary scores reflecting the inflammatory potential of the diet with DTC risk.

METHODS

Within the EPIC cohort, 450,063 participants were followed during a mean period of 14 years, and 712 newly incident DTC cases were identified. Associations between four dietary inflammatory scores [the dietary inflammatory index (DII®) and two energy-adjusted derivatives (the E-DIIr and the E-DIId), and the Inflammatory Score of the Diet (ISD)] and DTC risk were evaluated in the EPIC cohort using multivariable Cox regression models.

RESULTS

Positive associations were observed between DTC risk and the DIIs (HR for 1 SD increase in DII: 1.11, 95%CI: 1.01, 1.23, similar results for its derivatives), but not with the ISD (HR for 1 SD increase: 1.04, 95% CI 0.93, 1.16).

CONCLUSION

Diet-associated inflammation, as estimated by the DII and its derivatives, was weakly positively associated with DTC risk in a European adult population. These results suggesting that diet-associated inflammation acts in the etiology of DTC need to be validated in independent studies.

Different oral and gut microbial profiles in those with Alzheimer's disease consuming anti-inflammatory diets

The number of people living with Alzheimer's disease (AD) is increasing alongside with aging of the population. Systemic chronic inflammation and microbial imbalance may play an important role in the pathogenesis of AD. Inflammatory diets regulate both the host microbiomes and inflammatory status. This study aimed to explore the impact of inflammatory diets on oral-gut microbes in patients with AD and the relationship between microbes and markers of systemic inflammation. The dietary inflammatory properties and the oral and gut microorganisms were analyzed using the dietary inflammatory index (DII) and 16S RNA in 60 patients with AD. The α-diversity was not related to the DII (p > 0.05), whereas the β-diversity was different in the oral microbiomes (R² = 0.061, p = 0.013). In the most anti-inflammatory diet group, Prevotella and Olsenella were more abundant in oral microbiomes and Alistipes, Ruminococcus, Odoribacter, and unclassified Firmicutes were in the gut microbiomes (p < 0.05). Specific oral and gut genera were associated with interleukin-6 (IL)-6, complement 3 (C3), high-sensitivity C-reactive protein (hs-CRP), IL-1β, IL-4, IL-10, IL-12, and tumor necrosis factor-α (TNF-α) (p < 0.05). In conclusion, anti-inflammatory diets seem to be associated with increased abundance of beneficial microbes, and specific oral and gut microbial composition was associated with inflammatory markers.

Dietary Inflammatory Index (DII) is Associated with Movement-Evoked Pain Severity in Adults with Chronic Low Back Pain: Sociodemographic Differences

Chronic low back pain (CLBP) is one of the leading causes of pain and disability in adults in the United States and disproportionately burdens non-Hispanic Black (NHB) individuals and females. Approximately 90% of CLBP cases are of unknown cause, and it is imperative that potential causes be explored. It has been reported that diet quality can influence pain state via diet-induced inflammation. The present study assessed the relationship between Dietary Inflammatory Index (DII) and movement evoked-pain severity in people with CLBP and investigated whether race/sex moderated the relationship between DII and movement-evoked pain. Results revealed no significant differences in DII scores between males and females, or between NHB and non-Hispanic White (NHW) participants. Participant sex significantly modified the relationship between DII and movement-evoked pain severity (P = .0155), such that movement-evoked pain severity was significantly impacted by DII scores in females, but not males. Participant race did not significantly moderate the DII - movement-evoked pain severity relationship. These results suggest that diet-induced inflammation may impact the CLBP experiences of females to a greater degree than males. Further research is needed to determine whether dietary interventions that reduce inflammation improve CLBP outcomes and whether these interventions may be differentially-beneficial based on sex. PERSPECTIVE: This article highlights the impact of diet-induced inflammation in a community-based sample as a whole, as well as stratified in various sociodemographic groups. This work expands our understanding of the influence of diet on pain experience and suggests that modifications to diet may be efficacious treatments for reducing chronic pain.

Association of the Dietary Inflammatory Index with Depressive Symptoms among Pre- and Post-Menopausal Women: Findings from the National Health and Nutrition Examination Survey (NHANES) 2005-2010

During their lifetime, 20% of US women experience depression. Studies have indicated that a high Dietary Inflammatory Index (DII) score is associated with high C-reactive protein (CRP) levels and depression. No previous study has compared the association of the DII with different measures of depression (e.g., somatic, cognitive) among pre- and post-menopausal women. We used data from 2512 pre-menopausal and 2392 post-menopausal women from the National Health and Nutrition Examination Survey (NHANES) 2005−2010 database. We ran linear and logistic regression models to compare the association of the DII with survey-measured depression among pre- and post-menopausal women. We further assessed the mediation effect of CRP on the association of the DII and depression, using structural equation modeling. The odds of experiencing depression among pre-menopausal women was higher for all DII quartiles compared to the reference group (i.e., DII Q1), with an odds ratio (OR) of 3.2, 5.0, and 6.3 for Q2, Q3, and Q4, respectively (p < 0.05). Among post-menopausal women, only Q4 had 110% higher odds of experiencing depression compared to Q1 (p = 0.027). No mediation effect of CRP was found between DII and any of our depression outcome measures. Our findings suggest that lifestyle habits, such as diet, may have a stronger influence on mental health among pre-menopausal women than post-menopausal women.

The dietary inflammatory index is inversely associated with depression, which is minimally mediated by C-reactive protein

Depression affects 8% of adults in America and is one of the leading causes of disability in Western countries. The dietary inflammatory index (DII) has previously been reported to be associated with inflammation and depression. However, no study to date has looked at the potential mediating effect of inflammation on the association of DII and depression. We hypothesized that the association of DII and depression would be both statistically and clinically mediated substantially by inflammation. We assessed these associations using the cross-sectional National Health and Nutrition Examination Survey (NHANES) 2005-2010 database. Our analysis included 10,022 participants aged 20 years and older. Inflammation was assessed with C-reactive protein (CRP) levels. Diet was measured using two 24 hour dietary recalls. Depression was assessed using the 9-item Patient Health Questionnaire (PHQ-9), which has a score range of 0 to 27, with the higher score showing more severe depressive symptoms. Comparing the highest to lowest DII quartiles, the mean score difference for depression was 0.47 units (95% CI 0.24-0.70, P-trend <.001) in the multivariable adjusted model. In the sex-stratified models, the results remained significant only among females, with the mean score difference of 0.72 (95% CI 0.34-1.10, P-trend <.001). CRP mediated 3.6% of the association between DII and depression in the total population in the fully adjusted model, which was statistically significant (P-trend <.001) but not clinically significant. No mediation association was found in the sex-stratified models. Further studies are needed to assess the associations with various inflammatory biomarkers in larger and more diverse populations.

Adapted dietary inflammatory index and differentiated thyroid carcinoma risk in two French population-based case-control studies

PURPOSE

Thyroid cancer is the most common endocrine cancer and its etiology is still not well understood. The aim of the present study was to assess the association between an adapted dietary inflammatory index and differentiated thyroid cancer (DTC) risk in two population-based case-control studies (CATHY and YOUNG-THYR) conducted in France.

METHODS

These studies included a total of 1321 DTC cases and 1502 controls, for which an adapted dietary inflammatory index (ADII) was computed based on food frequency questionnaires in each study separately. The association between ADII and thyroid cancer risk was assessed using logistic regression models controlling for potential confounders.

RESULTS

Higher ADII scores, corresponding to a higher pro-inflammatory potential of the diet, were associated with higher DTC risk (odds ratio (OR) for 1 standard deviation (SD) increase: 1.09, 95% confidence interval (CI): 1.01, 1.18, P: 0.03). Associations were stronger in analyses restricted to women (OR for 1-SD increase: 1.14, 95% CI 1.04, 1.25, P: 0.005), as well as in women with lower education level, current smoking, or high body mass index.

CONCLUSION

Our study suggests that a pro-inflammatory diet is associated with an increased risk of DTC, especially when combined with other inflammatory conditions such as tobacco smoking or overweight. Our findings will help better understand the role of diet-induced inflammation in DTC etiology.

A Dietary Inflammatory Index and associations with C-reactive protein in a general adult population

PURPOSE

Chronic low-grade inflammation is implicated in many of the diseases of ageing. Lifestyle factors, including diet may alter low-grade inflammation. This study aimed to assess cross-sectional associations between the Dietary Inflammatory Index (DII) score and the inflammatory marker C-reactive protein (CRP); and determine if any association differs according to age (< 50 vs ≥ 50 years).

METHODS

DII scores were calculated for respondents of the Australian Health Survey 2011-2012 using data from two 24-h recalls. Serum CRP was measured using ultrasensitive immunoturbidimetric assay. Associations between DII and CRP were assessed using multivariate linear regression adjusting for confounders (age education, physical activity, sex and smoking). Associations were assessed for the whole cohort and stratified at age 50 years.

RESULTS

The analysis included 2558 respondents with a mean BMI of 26.8 kg/m² (< 50 years n = 1099; ≥ 50 years n = 1459). Respondents in the lowest DII quartile (anti-inflammatory diet) reportedly consumed more grains, vegetables and legumes, fruit, milk products, meat, poultry, fish and eggs, unsaturated oils and alcohol compared to respondents in DII quartile 4. No associations were seen between DII and CRP after adjustment for confounders in the whole cohort or when stratified < 50 or ≥ 50 years.

CONCLUSIONS

The DII was not associated with CRP in this cross-sectional study. Inflammation is complex characterised by a cascade of the multiple inflammatory markers and understanding the temporal relationship between diet and the inflammatory process is an important area for future research.

Associations between the dietary inflammatory index and urinary incontinence among women younger than 65 years

The purpose of this study was to evaluate the association between dietary inflammatory index (DII) and urinary incontinence (UI) among a representative sample of the US women. We performed a cross-sectional analysis of women younger than 65 years using the 1999 to 2016 NHANES (National Health and Nutrition Examination Survey) populations. DII were calculated based on baseline dietary intake using 24-h dietary recalls. UI was determined and categorized by self-reported questions. Multivariable logistic regression models were used to assess the association between DII and UI. Stratified linear regression models were applied to test for interaction in prespecified subgroup of interest. A total of 13,441 women age between 20 and 65 years were included in the final analysis. Of these participants 3230 (24.03%) complained of urgency UI, 5276 (39.25%) complained of stress UI and 2028 (15.09%) complained of mixed UI. On multivariate analysis, analysis with DII categorized as quartiles revealed significantly increase odds of urgency UI in the most pro-inflammatory quartile compared to the most anti-inflammatory quartile (OR 1.24, 95% CI 1.07–1.44, P = 0.004 for trend) in full adjustment model. Similar results were observed in SUI (OR 1.14, 95% CI 1.00–1.30, P = 0.021 for trend) and MUI (OR 1.20, 95% CI 1.02−1.43, P = 0.022 for trend). More pro-inflammatory diets, as presented by higher DII scores are associated with an increased likelihood of UI in American women younger than 65 years. Further studies are needed to explore the possible physiological mechanism and evaluate the potential therapeutic implications.

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.

Dietary patterns and associations with biomarkers of inflammation in adults: a systematic review of observational studies

Background

Evidence indicates that low-grade inflammation is involved in manychronic diseases of ageing. Modifiable lifestyle factors including dietcan affect low-grade inflammation. Dietary patterns allow assessment of the complex interactions of food nutrients and health and may be associated with inflammatory status.

This systematic review aimed to summarises current evidence from observational studies for associations between dietary patterns and inflammatory biomarkers in the general adult population. This review followed the PRISMA guidelines.

Methods

We conducted a systematic search in Embase, CINAHL Complete, Global Health and MEDLINE complete databases. Search terms included terms for diet (“dietary patterns”, “diet scores”) and inflammation (“inflammation“, “c-reactive protein“, “interleukin“).

Results

The search produced 7161 records. Duplicates were removed leaving 3164 for screening. There were 69 studies included (60 cross-sectional, 9 longitudinal). Papers included studies that were: 1) observational studies; 2) conducted in community-dwelling adults over 18 years of age; 3) assessed dietary patterns; 4) measured specified biomarkers of inflammation and 5) published in English. Dietary patterns were assessed using diet scores (n = 45), data-driven approaches (n = 22), both a data-driven approach and diet score (n = 2). The most frequently assessed biomarkers were CRP (n = 64) and/or IL-6 (n = 22). Cross-sectionally the majority of analyses reported an association between higher diet scores (mostly Mediterranean and anti-inflammatory diet scores) and lower inflammatory markers with 82 significant associations from 133 analyses. Only 22 of 145 cross-sectional analyses using data-driven approaches reported an association between a dietary patterns and lower inflammatory markers; the majority reported no association. Evidence of an association between dietary patterns and inflammatory markers longitudinally is limited, with the majority reporting no association.

Conclusions

Adherence to healthy, Mediterranean and anti-inflammatory dietary scores, appear to be associated with lower inflammatory status cross-sectionally. Future research could focus on longitudinal studies using a potential outcomes approach in the data analysis.

Trial registration

PROSPERO Registration Number CRD42019114501.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12937-021-00674-9.

Dietary Inflammatory Index and Epithelial Ovarian Cancer in Southern Chinese Women: A Case-Control Study

The association between inflammatory properties of diet and ovarian cancer risk has been investigated in some Western populations. However, little evidence is available from Asian women whose ovarian cancer incidence rates are low and dietary and lifestyle patterns are very different from their Western counterparts. We aimed to examine whether more pro-inflammatory diets, as indicated by higher dietary inflammatory index (DII®) scores, are associated with increased odds of epithelial ovarian cancer in southern China. A case-control study was conducted during 2006-2008 in Guangzhou, Guangdong Province. Energy-adjusted DII (E-DII) scores were calculated based on dietary intake assessed by a validated food frequency questionnaire administered to 500 incident epithelial ovarian cancer patients and 500 hospital-based controls. Logistic regression models were used to assess the relationship between E-DII scores and odds of ovarian cancer. Positive associations were observed between higher E-DII scores and ovarian cancer odds, using both continuous DII scores (odds ratio (OR) 1.87; 95% confidence interval (CI) 1.65, 2.13) and by DII tertiles (OR_tertile3vs1 7.04, 95% CI: 4.70, 10.54, p for trend < 0.001). Likewise, a more pro-inflammatory diet was associated with a higher chance of serous and mucinous ovarian tumors. Our results suggest that a pro-inflammatory diet was associated with increased odds of developing epithelial ovarian cancer in southern Chinese women. The findings add to epidemiological evidence for the role of dietary inflammatory potential in ovarian cancer development.

Absence of association between inflammatory dietary pattern and low trauma fractures: Results of the French cohort NutriNet-Santé

INTRODUCTION

The aim of our study was to assess the association between the Alternate Dietary Inflammatory Index (ADII) and the risk of fracture in a French cohort of women and men older than 50 years.

METHODS

A total of 15,096 participants were included from the French NutriNet-Santé cohort. The ADII score was calculated at inclusion. Incident low trauma fractures were retrospectively self-reported by participants on a specific additional questionnaire. Multivariate hazard ratio obtained from Cox proportional hazard regression models were used to characterize an association between ADII (in quartiles) and incident low trauma fractures.

RESULTS

In all, 12,046 participants (7607 (63.2%) women and 4439 (36.8%) men) were included in our study. For fractures, 806 (10.6%) and 191 (4.3%) low trauma fractures were recorded respectively in women and in men. Mean ADII was -1.23 (±3.13) for women and -0.87 (±3.64) for men. No association was detected between the ADII score and the risk of vertebral fracture (P=0.21), major osteoporotic fracture (P=0.93) and any low trauma fracture (P=0.72) in women nor in men (P=0.06 for major fracture and P=0.10 for low trauma fracture) after adjustment for sociodemographic, lifestyle variables and for bone treatments.

CONCLUSION

This study in postmenopausal women and men older than 50 years from the general population did not show any association between inflammatory dietary pattern measured using the ADII and the risk of incident low trauma fracture.

Impact of a 3-Month Anti-inflammatory Dietary Intervention Focusing on Watermelon on Body Habitus, Inflammation, and Metabolic Markers: A Pilot Study

An anti-inflammatory dietary intervention called the Inflammation Management Intervention (IMAGINE) was adapted to emphasize watermelon due to its anti-inflammatory properties. This pilot study (n = 23) tested the effect of a watermelon-enhanced IMAGINE intervention (n = 15) on body habitus and markers of inflammation and metabolism. This 3-month self-selection trial, consisting of weekly in-person classes and online education for 12 weeks, focused on incorporating watermelon into an already anti-inflammatory diet. Controls (n = 8) received basic health education via email and blogs. Measurements, including diet, anthropometrics, actigraphy, and a blood draw, were made at baseline and immediately postintervention. Linear regression analyses were conducted using intervention status as the main exposure. Post hoc analyses then ignored intervention assignment and grouped participants based on their change in their energy-adjusted Dietary Inflammatory Index (E-DIITM) score. There were no group-by-time interactions for any of the studied outcomes. However, some intervention participants' diets became more proinflammatory, and several control participants' diets became more anti-inflammatory. Those participants below the median of E-DII change (ie, more anti-inflammatory changes) showed reductions in body fat percent (-1.27% vs +0.90%, respectively, P = .01), body mass index (-0.66 vs +0.38 kg/m2, respectively, P = .06) and body weight (-0.99 vs +0.54 kg, respectively, P = .08) compared to those above the median of E-DII change. This study demonstrates that individuals who adopt a more anti-inflammatory diet containing watermelon will have improvements in body anthropometrics. Future studies should focus on increasing adherence and compliance to intervention prescriptions, exploring options to extend interventions to evaluate long-term changes, and further examining changes in inflammatory biomarkers. Clinical Trials Registration: NCT03158740.

Dietary Inflammatory Index and Non-Communicable Disease Risk: A Narrative Review

There are over 1,000,000 publications on diet and health and over 480,000 references on inflammation in the National Library of Medicine database. In addition, there have now been over 30,000 peer-reviewed articles published on the relationship between diet, inflammation, and health outcomes. Based on this voluminous literature, it is now recognized that low-grade, chronic systemic inflammation is associated with most non-communicable diseases (NCDs), including diabetes, obesity, cardiovascular disease, cancers, respiratory and musculoskeletal disorders, as well as impaired neurodevelopment and adverse mental health outcomes. Dietary components modulate inflammatory status. In recent years, the Dietary Inflammatory Index (DII®), a literature-derived dietary index, was developed to characterize the inflammatory potential of habitual diet. Subsequently, a large and rapidly growing body of research investigating associations between dietary inflammatory potential, determined by the DII, and risk of a wide range of NCDs has emerged. In this narrative review, we examine the current state of the science regarding relationships between the DII and cancer, cardiometabolic, respiratory and musculoskeletal diseases, neurodevelopment, and adverse mental health outcomes. We synthesize the findings from recent studies, discuss potential underlying mechanisms, and look to the future regarding novel applications of the adult and children's DII (C-DII) scores and new avenues of investigation in this field of nutritional research.

Higher Pro-Inflammatory Dietary Score is Associated with Higher Hyperuricemia Risk: Results from the Case-Controlled Korean Genome and Epidemiology Study_Cardiovascular Disease Association Study

In previous studies, the elevated dietary inflammatory index (DII®) scores have been consistently associated with several chronic diseases. However, the relationship with hyperuricemia remains unknown. The aim of this study was to determine if the DII is associated with hyperuricemia risk. The study included 13,701 participants (men 5102; women 8599) in a large-scale cross-sectional study in South Korea. A validated semi-quantitative food frequency questionnaire (SQFFQ) was used to measure dietary intake, and blood samples were obtained to determine hyperuricemia. As the DII score increased, the hyperuricemia risk increased among women (OR 1.35, 95% CI 1.03-1.77, p trend = 0.02). However, no significant results were found for men. Women with lower BMI scores had higher risks of hyperuricemia with higher DII scores (OR 1.62, 95% CI 1.05-2.52, p trend = 0.03). As the DII increased, however, only women who consumed alcohol ("past or current drinkers") had higher risks of hyperuricemia (OR 1.92, 1.22-3.02, p trend = 0.004). Among the DII components, intake of flavonoids showed a significant association with the hyperuricemia risk in women (OR 0.75, 0.59-0.96, p trend = 0.03). Our results suggest that higher intake of pro-inflammatory diet is significantly associated with higher risk of hyperuricemia among women. These results reinforce the importance of less pro-inflammatory habitual dietary patterns in lowering the risk of hyperuricemia and secondary afflictions such as cardiovascular diseases.

Dietary Inflammatory Index Is Associated with Risk of All-Cause and Cardiovascular Disease Mortality but Not with Cancer Mortality in Middle-Aged and Older Japanese Adults

BACKGROUND

The Dietary Inflammatory Index (DII) is a comprehensive, literature-derived index for assessing the effect of dietary constituents on inflammatory biomarkers. Several studies have shown an association between DII score and mortality, but there are limited prospective studies in Asian populations.

OBJECTIVES

The aim of this study was to investigate the association between DII score and risk of all-cause, total cardiovascular disease (CVD), stroke, coronary heart disease (CHD), total cancer, digestive cancer, and noncancer/non-CVD mortality in the Japanese population.

METHODS

A total of 58,782 Japanese participants aged 40-79 y who were enrolled in the Japan Collaborative Cohort Study during 1988-1990 were included in the analysis. DII scores were calculated based on a food-frequency questionnaire. HRs and 95% CIs for mortality according to DII quintiles were estimated using Cox proportional hazards models.

RESULTS

During the median follow-up period of 19.3 y, a total of 11,693 participants died. The multivariable HR for all-cause mortality for the highest compared with the lowest DII quintiles was 1.13 (95% CI: 1.05, 1.21). For CVD mortality, the highest multivariable HRs were 1.30 (95% CI: 1.13, 1.49), 1.29 (95% CI: 1.05, 1.59), and 1.30 (95% CI: 0.96, 1.76) for total CVD, stroke, and CHD, respectively. No significant associations were observed between DII and risk of total cancer, digestive cancer, and noncancer/non-CVD mortality.

CONCLUSION

Our findings suggest that a higher DII was associated with an increased risk of all-cause and CVD mortality among Japanese adults.

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.

Dietary inflammatory index and risk of gynecological cancers: a systematic review and meta-analysis of observational studies

OBJECTIVE

There has been growing body of literatures showing that chronic inflammation might play an important role in cancer development. This meta-analysis aimed to assess the association between the dietary inflammation index (DII) score and gynecological cancers.

METHODS

A systematic search of PubMed, EMBASE and Web of Science up until October 20, 2018 was carried out to retrieve all related cohort and case-control studies. The summary risk assessments were pooled using random-effects models. The dose-response relationship was estimated by linear relationship model.

RESULTS

Twelve case-control studies (10,774 cases/15,958 controls) and six prospective cohort studies (330,363 participants/23,133 incident cases) were included in this meta-analysis. The pooled adjusted relative risk (RR) of gynecological cancers for the highest DII category compared to the lowest category was 1.38, (95% confidence intervals [CIs], 1.21-1.56, p<0.001]. A positive dose-response relationship was also noticed. Stratified by study design indicated that, the pooled RRs was significantly higher for case-control studies than cohort studies (p for interaction<0.001), for studies conducted among participants with body mass index (BMI) ≥25 kg/m² than participants with BMI <25 kg/m² (p for interaction=0.026), among participants with ovarian cancer and endometrial cancer than participants with breast cancer (p for interaction = 0.038). Meta-regression analysis further confirmed that study design significantly contributed to inter-study heterogeneity (p<0.001).

CONCLUSION

This meta-analysis suggests that elevated DII is independently associated with a higher risk of gynecological cancers, especially patients with ovarian cancer and endometrial cancer and among obese participants.

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.

Impact of a 12-month Inflammation Management Intervention on the Dietary Inflammatory Index, inflammation, and lipids

BACKGROUND AND AIMS

The objective of this study was to assess the feasibility (ability to recruit participants and develop the 12-month intervention), acceptability (retention of participants in the intervention), and impact on systemic inflammation and Dietary Inflammatory Index (DII®) scores over a 12-month DII-based intervention.

METHODS

Adults were recruited to participate in a self-selection trial (intervention: n = 61, in-person classes; control: n = 34, newsletters). Classes included participatory cooking and dietary recommendations focused on consuming a plant-based diet rich in anti-inflammatory foods (spices, vegetables, etc.). Changes in markers of inflammation, lipids, and DII were analyzed using general linear models with repeated measurements.

RESULTS

At 3 months, intervention participants had significantly lower DII scores (-2.66 ± 2.44) compared to controls (-0.38 ± 2.56) (p < 0.01); but not at 12 months (P = 0.10). The only biomarker to approach a significant group effect or group-by-time interaction was CRP (P = 0.11 for the group-by-time interaction). CRP decreased by -0.65 mg/L (95%CI = 0.10-1.20, P = 0.02) at 12 months in the intervention group; no significant decrease was seen for the control group. With both groups combined at 3 months, those with the greatest decrease/improvement in DII score (tertile 1) compared with those whose scores increased (tertile 3) had greater reductions in CRP (-1.09 vs. +0.52 mg/L, P = 0.04), total cholesterol (-9.38 vs. +12.02 mg/dL, P = 0.01), and LDL cholesterol (-11.99 vs. +7.16 mg/dL, P = 0.01).

CONCLUSIONS

Although the intervention group had reductions in DII and CRP, main inflammation and lipid outcomes did not differ between groups. Overall, those participants with the largest reduction in DII scores had the largest reductions in CRP and LDL and total cholesterol. Future interventions may need to have more components in place to support maintenance and continued reductions in the DII. CLINICALTRIALS.

GOV IDENTIFIER

NCT02382458.

Dietary Inflammatory Index Positively Associated With High-Sensitivity C-Reactive Protein Level in Japanese From NIPPON DATA2010

Background

It has been reported that chronic inflammation may play an important role in the pathogenesis of several serious diseases and could be modulated by diet. Recently, the Dietary Inflammatory Index (DII^®) was developed to assess the inflammatory potential of the overall diet. The DII has been reported as relevant to various diseases but has not been validated in Japanese. Thus, in the present study, we analyzed the relationship between DII scores and high-sensitivity C-reactive protein (hs-CRP) levels in a Japanese population.

Methods

Data of the National Integrated Project for Prospective Observation of Non-communicable Disease and its Trends in the Aged 2010 (NIPPON DATA2010), which contained 2,898 participants aged 20 years or older from the National Health and Nutrition Survey of Japan (NHNS2010), were analyzed. Nutrient intakes derived from 1-day semi-weighing dietary records were used to calculate DII scores. Energy was adjusted using the residual method. Levels of hs-CRP were evaluated using nephelometric immunoassay. Multiple linear regression analyses were performed.

Results

After adjusting for age, sex, smoking status, BMI, and physical activity, a significant association was observed between DII scores and log(CRP+1) (standard regression coefficient = 0.05, P < 0.01). Although it was not statistically significant, the positive association was consistently observed in almost all age-sex subgroups and the non-smoker subgroup.

Conclusions

The current study confirmed that DII score was positively associated with hs-CRP in Japanese.

Associations between Dietary Inflammatory Index Scores and Inflammatory Biomarkers among Older Adults in the Lothian Birth Cohort 1936 Study

OBJECTIVES

Chronic low-grade inflammation is a key underlying mechanism in several age-related chronic conditions and previous studies have shown that diet can modulate the inflammatory process. We investigated the ability of the Dietary Inflammatory Index (DII®), a summary measure of dietary inflammatory potential, to predict concentrations of plasma inflammatory markers in a sample of older people.

DESIGN

Cross-sectional and 3-year follow-up analysis of Lothian Birth Cohort 1936 (LBC1936) study data.

SETTING

Baseline data collection occurred between 2004 and 2007 in Edinburgh, Scotland.

PARTICIPANTS

Men and women (n 928, age ~70 at baseline) living in Edinburgh and surrounding regions who are surviving participants of the Scottish Mental Survey of 1947.

MEASUREMENTS

Energy-adjusted DII (E-DII) scores at age 70 (derived from a food-frequency questionnaire), plasma concentrations of inflammatory biomarkers at age 70 (C-reactive protein (CRP), fibrinogen) and age 73 (CRP, fibrinogen, hs-CRP, Interleukin-6 (IL-6)). Analyses were performed using multivariable logistic regression adjusting for age, sex, smoking, body mass index, physical activity, and hypercholesterolaemia.

RESULTS

Higher E-DII scores (pro-inflammatory diet) were associated with increased odds of elevated CRP (>3mg/L) at age 70 (OR 1.12; 95% CI: 1.02, 1.24, P = 0.02), and elevated IL-6 (>1.6pg/ml) at age 73 (OR 1.11; 95% CI: 1.00, 1.23, P = 0.04), but not with fibrinogen.

CONCLUSION

These results are consistent with the ability of the DII to predict inflammatory biomarker concentrations and suggest that diet plays a role in the regulation of inflammation, even after controlling for potential confounders. This validation study provides support for using the DII in research among older populations.

The dietary inflammatory index and insulin resistance or metabolic syndrome in young adults

OBJECTIVE

The aim of this study was to assess the association between the inflammatory potential of diet, as measured by the dietary inflammatory index (DII) and insulin resistance (IR) or metabolic syndrome (MetS).

METHODS

A cross-sectional study (nested within a cohort) was conducted on 2017 adults 23 to 25 y of age in Ribeirão Preto, Brazil. Food consumption was assessed using a validated food frequency questionnaire. DII scores were calculated from 35 available food parameters. IR was determined from the classification of homeostatic model assessment (HOMA) values (≥2.7 uU mL-1). MetS was diagnosed based on the Joint Interim Statement (JIS) criterion. The association of DII score with IR or MetS was determined by Poisson regression analysis. The variables included in the multivariable model were selected from directed acyclic graphs.

RESULTS

The diet of the young adults studied showed a high inflammatory potential, with a mean DII score of +1.10 (range: -4.69 to +5.28). The prevalence of MetS was 12.2% and IR 12.3%; both were higher in men than in women. The correlation between DII and HOMA-IR values was -0.038 (P = 0.09). The DII was not associated with IR or MetS in either sex.

CONCLUSION

Although the association between DII and the outcomes was not detected in this sample, the study demonstrated that the diets of these young adult Brazilians had a high inflammatory potential when compared with other studies. Future studies, preferably using longitudinal designs, are recommended.

Meta-analysis of the association between the dietary inflammatory index (DII) and breast cancer risk

BACKGROUND

Recent studies have reported mixed results on the association between the pro-inflammatory dietary index and risk of breast cancer. We perform this comprehensive meta-analysis to figure out whether high dietary inflammatory index (DII) score is a risk factor for the occurrence of breast cancer.

METHODS

We comprehensively searched the PubMed, EMBASE and Cochrane databases to identify included studies updated to September 12, 2017. All studies that reported risk estimates by comparing the highest DII score to the lowest were assessed.

RESULTS

A total of seven observational studies were identified: three case controls and four cohorts, involving 319,993 participants. Overall, the meta-analysis reported that individuals with the highest DII score were associated with a 25% increased risk of breast cancer versus those with the lowest DII score (relative risk [RR] = 1.25; 95% confidence interval [CI] 1.09-1.44; I² = 82.7%, p = 0.000). Upon stratified analysis, significant positive associations remained for postmenopausal women (RR = 1.15; 95% CI 1.02-1.30; p = 0.020), case-control studies (RR = 1.68; 95% CI 1.13-2.49; p = 0.010), Asia (RR = 2.30; 95% CI 1.7-3.12; p = 0.0031) and Europe (RR = 1.26; 95% CI 1.01-1.58; p = 0.0477). When analysed on hormonal receptor status, 36% increased risk was explored for hormone-receptor negative.

CONCLUSION

This meta-analysis suggested that more pro-inflammatory diets (higher DII scores) are associated with increased breast cancer incidence. However, the research is not about significant associations but about moderate effect sizes.

Improvement in dietary inflammatory index score after 6-month dietary intervention is associated with reduction in interleukin-6 in patients with coronary heart disease: The AUSMED heart trial

The Dietary Inflammatory Index (DII) was designed to measure the inflammatory potential of one's diet. Evidence from observational studies supports that a higher (ie, more pro-inflammatory) DII score is associated with inflammation and cardiometabolic diseases. We hypothesized that reduction in DII score would improve inflammatory cytokines. To test this hypothesis, we assessed data from a dietary intervention trial in patients with diagnosed coronary heart disease (CHD) to determine whether reduction in DII scores through healthy diets is linked to improvement in inflammatory and related cardiometabolic risk markers. Participants (n = 65, 83% male) were randomized to a Mediterranean diet or low-fat diet intervention for 6-months. Anthropometry, body composition and blood markers were measured and DII scores were calculated from 7-day food diaries. After 6-months, in participants who completed the intervention (n = 56), reduction in DII score correlated significantly with reduction in high sensitivity interleukin-6 (hs-IL-6) (r = 0.34, 95% CI 0.05, 0.56) and triglycerides (r = -0.30, 95% CI -0.51, -0.06) but not with C-reactive protein, adiponectin, glucose, body composition or anthropometry. The adjusted mean difference in hs-IL-6 and triglycerides between the highest and lowest tertiles of DII improvement was -0.47 pg/mL (95% CI 0.41, 1.10) and +0.30 mmol/L (95% CI 1.06, 1.59), respectively. The present study found that improvement in DII score through healthy diet intervention was linked with reduced levels of hs-IL-6, but also increased triglycerides, in adult Australian patients with CHD. Future research is warranted to investigate the impact of change in DII on cardiometabolic risk markers in larger cohorts, other disease populations or healthy subjects and with longer-term follow up.

The Dietary Inflammatory Index is associated with elevated white blood cell counts in the National Health and Nutrition Examination Survey

White blood cells (WBCs) are considered a reliable biomarker of inflammation. Elevations in both WBCs and pro-inflammatory cytokines are associated with several chronic conditions. Diet is a strong moderator of inflammation and WBCs. The purpose of this study was to examine the association between the Dietary Inflammatory Index (DII®) and WBCs using data from the United States National Health and Nutrition Examination Survey (NHANES). NHANES is a cross-sectional study that occurs in two-year cycles. Respondents from five cycles (n = 26,046) with available data on diet (collected through a single 24-h dietary recall [24HR]) and WBCs (derived using the Coulter method) were included. The DII (theoretical range is about -8 to +8) was derived from the micro and macronutrients calculated from the 24HR. Linear regression models, using survey design procedures, were used to estimate adjusted mean WBC (i.e., total, lymphocytes, monocytes, and neutrophils) counts and percentages by DII quartiles. Among all participants no statistically significant difference in WBCs were observed when comparing DII quartile 4 (most pro-inflammatory) to quartile 1 (most anti-inflammatory). However, a one-unit increase in the DII was associated with a 0.028 (1000 per µL) increase in total WBCs (p = .01). Additionally, a 0.024 increase in neutrophils (p < .01) was observed for a one-unit increase in the DII. In the group of participants with normal body mass index (BMI, 18.5-24.9 kg/m²), those in DII quartile 4 had higher levels of total WBCs compared to subjects with normal BMI in DII quartile 1 (7.12 vs. 6.88, p = .01). Similar comparisons were observed for monocytes and neutrophils. However, these relationships were not observed for participants who were overweight or obese, which are pro-inflammatory conditions. Normal-weight individuals consuming more pro-inflammatory diets were more likely to have elevated WBCs. Because of its cross-sectional design, NHANES cannot inform directly on temporal relations, thus limiting causal inference. Future research is needed to examine the impact of anti-inflammatory diet adoption on lowering levels of WBCs, in addition to other inflammatory mediators.

The Inflammatory Potential of the Diet at Midlife Is Associated with Later Healthy Aging in French Adults

Background

While low-grade chronic inflammation has been suggested as a major modulator of healthy aging (HA), no study has yet investigated the link between the inflammatory potential of the diet and multidimensional concepts of HA.

Objective

We aimed to evaluate the association between the inflammatory potential of the diet at midlife, as measured by the Dietary Inflammatory Index (DII), and HA assessed 13 y later.

Methods

We analyzed data from 2796 participants in the French Supplémentation en Vitamines et Minéraux Antioxydants (SU.VI.MAX) study aged 45-60 y at baseline (1994-1995) and initially free of diabetes, cardiovascular disease, and cancer. During the trial phase of the study (1994-2002), participants received either a placebo or a daily nutritional dose of antioxidant supplement (120 mg vitamin C, 6 mg β-carotene, 30 mg vitamin E, 100 μg Se, 20 mg Zn). HA was assessed in 2007-2009, and defined as having no major chronic disease, good physical and cognitive functioning, independence in daily activities, no depressive symptoms, good social health, good overall self-perceived health, and no function-limiting pain. The DII was calculated based on repeated baseline 24-h dietary records. Its association with HA was assessed by robust-error-variance Poisson regression, providing RR estimates.

Results

After adjustment for potential confounders, higher DII scores (reflecting a more proinflammatory diet), were associated with a decreased likelihood of HA: RRtertile 3/tertile 1 = 0.85 (95% CI: 0.74, 0.99); P-trend = 0.03. Secondary analyses revealed that this association was only significant among participants who had been in the placebo group during the trial phase: RRtertile 3/tertile 1 = 0.80 (95% CI: 0.64, 1.00); P-trend = 0.04.

Conclusions

This study suggests that a proinflammatory diet may lower the probability of overall HA. The SU.VI.MAX trial was registered at www.clinicaltrials.gov as NCT00272428.

Dietary Inflammatory Index and Cardiovascular Risk and Mortality-A Meta-Analysis

Diet and chronic inflammation have been suggested to be risk factors in the development of cardiovascular disease (CVD) and related mortality. The possible link between the inflammatory potential of diet measured through the Dietary Inflammatory Index (DII^®) and CVD has been investigated in several populations across the world. The aim of this study was to conduct a meta-analysis on studies exploring this association. Data from 14 studies were eligible, of which two were case-control, eleven were cohort, and one was cross-sectional. Results from the random-effects meta-analysis showed a positive association between increasing DII, indicating a pro-inflammatory diet, and CVD. Individuals in the highest versus the lowest (reference) DII category showed a 36% increased risk of CVD incidence and mortality, with moderate evidence of heterogeneity (relative risk (RR) = 1.36, 95% confidence interval (CI): 1.19, 1.57; heterogeneity index I² = 69%, p < 0.001). When analyzed as a continuous variable, results showed an increased risk of CVD risk and mortality of 8% for each one-point increase in the DII score. Results remained unchanged when analyses were restricted to the prospective studies. Results of our meta-analysis support the importance of adopting a healthier anti-inflammatory diet for preventing CVD incidence and related mortality. In conclusion, a pro-inflammatory diet is associated with increased risk of CVD and CVD mortality. These results further substantiate the utility of DII as tool to characterize the inflammatory potential of diet and to predict CVD incidence and mortality.

Lower Dietary Inflammatory Index Scores Are Associated with Lower Glycemic Index Scores among College Students

The association between the Dietary Inflammatory Index (DII^®), the glycemic index (GI), and the glycemic load (GL) is not known, although it is known that carbohydrates are pro-inflammatory. We aimed to measure the association between the DII and both GI and GL among college students. In this cross-sectional study, 110 college students completed a 3-day food diary, which was used to calculate the DII, the GI, the GL, and the healthy eating index (HEI)-2010. Least square means and 95% confidence intervals of the GI, the GL, and the HEI-2010 were presented per DII tertile using generalized linear mixed models. Participants in tertile 1 of DII scores had lower GI and GL scores, but higher HEI-2010 scores than those in tertile 3. Pearson correlations showed that DII score was positively correlated with the GI score (r = 0.30, p < 0.01), but negatively correlated with the HEI-2010 (r = −0.56, p < 0.001). DII score was not correlated with GL score. Results from this study suggest that increased inflammatory potential of diet, as represented by higher DII scores, was associated with increased GI scores and lower quality of diet on the HEI-2010. Use of the DII suggests new directions for dietary approaches for preventing chronic diseases that moves beyond convention by decreasing systemic inflammation.

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.

Dietary Inflammatory Index and Colorectal Cancer Risk-A Meta-Analysis

Diet and chronic inflammation of the colon have been suggested to be risk factors in the development of colorectal cancer (CRC). The possible link between inflammatory potential of diet, measured through the Dietary Inflammatory Index (DII^®), and CRC has been investigated in several populations across the world. The aim of this study was to conduct a meta-analysis on studies exploring this association. Data from nine studies were eligible, of which five were case-control and four were cohort studies. Results from meta-analysis showed a positive association between increasing DII scores, indicating a pro-inflammatory diet, and CRC. Individuals in the highest versus the lowest (reference) DII category showed an overall 40% increased risk of CRC with moderate evidence of heterogeneity [relative risk (RR) = 1.40, 95% confidence interval (CI): 1.26, 1.55; I² = 69%, p < 0.001]. When analyzed as a continuous variable, results showed an increased risk of CRC of 7% for a 1-point increase in the DII score. Results remained unchanged when analyses were restricted to the four prospective studies. Results of our meta-analysis support the importance of adopting a healthier anti-inflammatory diet in preventing CRC. These results further substantiate the utility of DII as tool to characterize the inflammatory potential of diet and to predict CRC.