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

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.

TNF-α Mediates the Association between Dietary Inflammatory Index and Depressive Symptoms in Breast Cancer

This study examined the association between the energy-adjusted Dietary Inflammatory Index (E-DII)-based dietary inflammatory potential and depressive symptoms (DepS) among patients with breast cancer and explores whether systemic inflammation mediates this association. We assessed dietary intake and DepS in 220 breast cancer patients by three 24 h dietary recalls and the Center for Epidemiological Studies Depression Scale (CES-D), respectively, and determined plasma levels of C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), and interleukin (IL)-1β, IL-4, and IL-6 in 123 blood samples. We found that each one-point increase of E-DII was related to a 53% elevated risk of DepS. Patients with the most pro-inflammatory diets had a 5.13 times higher risk of DepS than those with the most anti-inflammatory diets. Among the E-DII components, vitamin B₂, zinc, and iron were inversely associated with DepS risk. Furthermore, E-DII scores were positively associated with CRP and TNF-α. Higher levels of TNF-α and IL-6 were associated with higher DepS risk. A significant mediating effect of TNF-α was revealed between E-DII and DepS. Our findings suggest that a pro-inflammatory diet is positively associated with breast cancer-related DepS, which may be mediated by TNF-α.

Relationship between Dietary Inflammatory Index and Postpartum Depression in Exclusively Breastfeeding Women

(1) Background: Research has shown that chronic inflammation can increase the risk of depression. The dietary inflammatory index (DII) is a novel measure of dietary inflammation, which has been used to investigate the relationship between diet and mental disorders in adults. However, little research has been conducted to establish an association between dietary inflammation (as measured by DII) and postpartum depression (PPD) in exclusively breastfeeding women. (2) Methods: In this cross-sectional study, 293 women who were exclusively breastfeeding for 6 months or less were enrolled. The DII scores were evaluated using semi-quantitative Food Frequency Questionnaires (FFQ), and the Edinburgh Postpartum Depression Scale (EPDS) was used to measure depression levels of breastfeeding mothers during the six months following delivery. The participants were classified by tertiles, and the possibility of DII being associated with PPD was assessed by binary regression analysis. (3) Results: The average DII score was 2.32 ± 1.08, which ranged from -1.66 to 4.19. The rate of depression was 60.1%. Adjusted for potential risk factors such as age, educational level, occupational level, number of babies, number of caregivers, social support level, and sleep quality, the results showed that the lowest DII score was associated with a lower risk of PPD than the highest score (OR tertile Q₁ vs. 3 = 0.47, 95% CI: 0.24, 0.93, p = 0.030). (4) Conclusions: In exclusive breastfeeding women, the inflammatory potential of dietary intake seems to be related to depression. Interventions to improve diet quality might consider including a dietary component that aims to lower chronic systemic inflammation to prevent PPD. However, the relationship between DII and PPD among Chinese women remains to be demonstrated in a larger population.

Relationship between leisure-time physical activity and depressive symptoms under different levels of dietary inflammatory index

Depressive symptoms are major public health problems. Leisure-time Physical activity (LPA) and dietary inflammatory preference are emerging factors that tends to affect the mental health status. There is limited evidence regarding the joint influence of LPA and dietary status on the prevalence of depression. This study was a cross-sectional study, which used a nationwide represented sample from the National Health and Nutrition Examination Survey (NHANES) to assess the relationship among LPA, diet status and depression. Depression and LPA status was reported by the 9-item Patient Health Questionnaire (PHQ-9) and Physical Activity Questionnaire (PAQ), respectively. To assess dietary inflammatory preferences, dietary inflammatory index (DII) was applied based on a 24-h dietary recall interview. A total of 11,078 subjects was included in this study and weighted participants were 89,682,020. Weighted multivariable linear regression showed that DII was negatively associated with LPA after full adjustment, with β (95% CI): −0.487 (−0.647, −0.327). Weighted multivariable logistic regression showed that LPA was significantly associated with depressive symptoms after full adjustment, with odds ratios OR (95% CIs): 0.986 (0.977, 0.995). By DII stratification analysis, this phenomenon was also existed in groups with anti-inflammatory diet. Mediation effect analysis was further performed, which showed that DII significantly mediating the association between LPA and depression with proportion mediated as 3.94%. Our findings indicated the mediating role of DII in the association between LPA condition and incident depression. More well-designed studies are still needed to validate the causal relationship.

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.

Inflammation mediated the effect of dietary fiber on depressive symptoms

BACKGROUND AND AIMS

Previous studies showed that inflammation affects depressive symptoms. Dietary fiber may be associated with inflammation and depressive symptoms. We aimed to investigate the relationship between inflammation and depressive symptoms at different levels of dietary fiber intake and to explore whether dietary fiber affects depression through inflammation.

METHODS

A total of 8,430 National Health and Nutrition Examination Survey (NHANES) samples were collected between 2015 and 2018. Factor analysis was used to determine dietary patterns. Linear regression and logistic regression analysis were used to explore the relationship between nutrients, inflammation, and depressive symptoms, and the mediation analysis was conducted using the bootstrap method.

RESULTS

Factor 3 (dietary fiber and vitamins) was inversely associated with depressive symptoms and inflammation. The upper quartile scores of the dietary inflammatory index (DII) and C-reactive protein (CRP) were associated with depressive symptoms compared with controls (DII: OR = 1.851, 95% CI: 1.267-2.705; CRP: OR = 1.737, 95% CI: 1.136-2.656). The DII score and CRP were associated with depressive symptoms in the group with low dietary fiber intake (DII: OR = 2.736, 95% CI: 1.628-4.598; CRP: OR = 2.092, 95% CI: 1.196-3.658) but not in the high dietary fiber intake group. Mediating analysis showed that CRP partially mediated the effect of dietary fiber intake on depressive symptoms (β_indirect = -0.0025, 95% CI: -0.0038 to -0.0013), and the mediated proportion was 10.5%.

CONCLUSION

In this study, we found that DII scores and CRP were not associated with depressive symptoms in participants with high dietary fiber intake, and inflammation partially mediates the effect of dietary fiber on depressive symptoms.