Validating the dietary inflammatory index using inflammatory biomarkers in a Japanese population: A cross-sectional study of the JPHC-FFQ validation study.

Persistent low-grade inflammation is related to the development of many chronic diseases. The dietary inflammatory index (DII®) is designed to assess the potential effects of diet on an individual's inflammation status. The aim of this study was to evaluate the construct validity of the DII using inflammation biomarkers in Japanese adults. Overall, 565 participants from the food frequency questionnaire (FFQ) validation study of the Japan Public Health Center-Based Prospective Cohort were included in the present study. This cohort consisted of two independently recruited and examined, cohorts I and II. Dietary records (DR) were collected for 28 d and two FFQs were administered. Blood samples also were obtained for the analysis of high-sensitivity C-reactive protein (hs-CRP) and interleukin (IL)-6 concentrations. DII scores were calculated from DR and FFQ using energy-adjusted dietary intakes by the density method. Higher DII scores indicate a greater proinflammatory potential of the diet. The associations between DII and inflammatory biomarkers were assessed using regression models adjusted for age, body mass index, smoking status, and amount of physical activity. The associations between DR- and FFQ-derived DII scores were moderate. Higher DR-derived DII scores, representing a more proinflammatory diet, were significantly correlated with IL-6, but not hs-CRP, concentrations in men. The geometric means of IL-6 concentrations in the lowest and highest DII quartiles were 1.05 and 1.33 pg/mL (P = 0.02 for trend) in cohort I, and 1.00 and 1.24 pg/mL (P = 0.03 for trend) in cohort II, respectively. Furthermore, IL-6 concentration appeared to increase across DII quartiles calculated from FFQ in men. However, there was no association between DII and inflammatory biomarkers in women. Null findings in women may reflect the generally lower levels of chronic systemic inflammation among Japanese versus their Western counterparts. These findings indicate that DII may be applied to measure the potential effects of diet on chronic diseases through inflammatory pathways in Japanese men.

Kotemori A ，Sawada N ，Iwasaki M ，Yamaji T ，Shivappa N ，Hebert JR ，Ishihara J ，Inoue M ，Tsugane S ，JPHC FFQ Validation Study Group ... -  《-》

Dietary Inflammatory Index Is Associated With Inflammation in Japanese Men.

Background: Dietary components are known to affect chronic low-grade inflammation status. The dietary inflammatory index (DII®) was developed to measure the potential impact of a diet on an individual's inflammatory status, and it has been validated mainly in Western countries. Objective: This study aimed to examine the validity of the energy-adjusted DII (E-DIITM) using high-sensitivity C-reactive protein (hs-CRP) concentration in Japanese men and women. Methods: In total, 6,474 volunteers from a cancer-screening program (3,825 men and 2,649 women) completed a food frequency questionnaire (FFQ) and their hs-CRP concentrations were evaluated. E-DII scores were calculated on the basis of 30 food parameters derived from the FFQ. Higher E-DII scores reflect a greater pro-inflammatory potential of the diet. The associations between E-DII quartiles and hs-CRP concentration were assessed using regression models adjusted for age, body mass index, smoking status, and amount of physical activity. Results: Mean E-DII in men and women was + 0.62 ± 1.93 and -1.01 ± 2.25, respectively. The proportion of men and women who had hs-CRP concentration >3 mg/L was 4.7 and 3.1%, respectively. A significant positive association was observed between E-DII score and hs-CRP concentration in men; geometric mean of hs-CRP concentration in the lowest and highest E-DII quartiles was 0.56 mg/L and 0.67 mg/L (P trend < 0.01), respectively. The odds ratio (95% confidence interval) of having an elevated hs-CRP concentration (>3 mg/L) was 1.72 (1.10-2.67) in the highest E-DII quartile (P trend = 0.03) in men. However, no association was observed between E-DII score and hs-CRP concentration in women, except in those not taking prescription medications. Conclusions: DII was associated with inflammation status in Japanese men, but the association was limited in Japanese women.

Kotemori A ，Sawada N ，Iwasaki M ，Yamaji T ，Shivappa N ，Hebert JR ，Ishihara J ，Inoue M ，Tsugane S ... -  《Frontiers in Nutrition》

Dietary inflammatory index is positively associated with serum high-sensitivity C-reactive protein in a Korean adult population.

To our knowledge, only a few studies have explored the relationship between the inflammatory potential of diet and serum inflammatory markers in Korean adults. The likely novel aim of this study was to examine the association between the dietary inflammatory index (DII) and serum high-sensitivity C-reactive protein (hs-CRP) in a Korean adult population. A cross-sectional study was conducted using the data set from the Korea National Health and Nutrition Examination Survey (KNHANES) 2015. Korean adults ≥19 y of age with hs-CRP values were included in this study. After excluding individuals with missing variables for covariates, the final analytic sample for the study was 3014 adults (1295 men and 1719 women). DII scores were calculated from a 1-d 24-h dietary recall, and hs-CRP was measured using the immunoturbidimetric method. Multivariable logistic regression analyses were performed to calculate adjusted odds ratios (AORs) and 95% confidence intervals (CIs) to test the effect of the DII score on serum hs-CRP as dichotomous (>2 versus ≤2 mg/L). A significant association was observed between increasing DII scores and elevated hs-CRP. Korean adults in the highest quintile of the DII (indicating the most proinflammatory diet), compared with the lowest quintile of the DII (indicating the most anti-inflammatory diet), had increased odds of having elevated hs-CRP concentrations (>2 mg/L; AOR, 1.70; 95% CI, 1.07-2.69; Ptrend < 0.0001) after controlling for age, sex, education, marital status, alcohol consumption, smoking status, body mass index, high-density lipoprotein cholesterol, and physical activity. Higher DII scores were positively associated with elevated hs-CRP levels in Korean adults. Because inflammation affects the risk for cancer, cardiovascular disease, and other inflammation-related conditions, future studies are warranted to examine the effect of the DII on other inflammatory biomarkers and chronic disease outcomes among the Korean population.

Shin D ，Lee KW ，Brann L ，Shivappa N ，Hébert JR ... -  《-》

Dietary Inflammatory Index and Biomarkers of Lipoprotein Metabolism, Inflammation and Glucose Homeostasis in Adults.

Phillips CM ，Shivappa N ，Hébert JR ，Perry IJ ... -  《Nutrients》

Association between dietary inflammatory index and serum C-reactive protein concentrations in the Japan Collaborative Cohort Study.

Suzuki K ，Shivappa N ，Kawado M ，Yamada H ，Hashimoto S ，Wakai K ，Iso H ，Okada E ，Fujii R ，Hébert JR ，Tamakoshi A ... -  《Nagoya Journal of Medical Science》