Michael D. Wirth

Association of a Dietary Inflammatory Index With Inflammatory Indices and Metabolic Syndrome Among Police Officers

Objectives:To determine whether the dietary inflammatory index (DII) is associated with inflammatory or metabolic biomarkers and metabolic syndrome (MetSyn) among police officers. Methods:Cross-sectional data from the Buffalo Cardio-Metabolic Occupational Police Stress study were derived from saliva and fasting blood samples, anthropometric measurements, long-term shiftwork histories, and demographic, stress/depression, and food frequency questionnaires (FFQs). Metabolic syndrome was defined using standard criteria. Results:Officers in DII quartiles 2 to 4 were more likely to exceed a threshold of 3.0 mg/L for C-reactive protein (odds ratio [OR] = 1.88; 95% confidence interval [95% CI] = 1.02 to 3.45; OR = 2.17; 95% CI = 1.19 to 3.95; OR = 1.57; 95% CI = 0.85 to 2.88, respectively) compared with quartile 1. The glucose intolerance component of MetSyn was more prevalent among officers in DII quartile 4 than among those in quartile 1 (OR = 2.03; 95% CI = 1.08 to 3.82). Conclusions:A pro-inflammatory diet was associated with elevated CRP and with the glucose intolerance component of MetSyn.

Dietary inflammatory index scores differ by shift work status: NHANES 2005 to 2010.

Objective: Shift workers are affected by diet- and inflammation-related diseases, including cardiovascular disease, diabetes, and cancer. We examined a dietary inflammatory index (DII) in relation to shift work from the National Health and Nutrition Examination Survey data (2005 to 2010). Methods: The DII was calculated using data from a 24-hour dietary recall. Shift work categories included day workers, evening/night shift workers, or rotating shift workers. General linear models were fit to examine the relationship between shift work and adjusted mean DII values. Results: Among all shift workers and specifically rotating shift workers, higher (ie, more pro-inflammatory) mean DII scores (1.01 and 1.07 vs 0.86; both P ⩽ 0.01) were observed compared with day workers. Women tended to express strong evening/night shift effects. Conclusions: More proinflammatory diets observed among shift workers may partially explain increased inflammation-related chronic disease risk observed in other studies among shift workers compared with their day-working counterparts.

Randomization to plant-based dietary approaches leads to larger short-term improvements in Dietary Inflammatory Index scores and macronutrient intake compared with diets that contain meat

Studies have examined nutrient differences among people following different plant-based diets. However, all of these studies have been observational. The aim of the present study was to examine differences in nutrient intake and Dietary Inflammatory Index (DII) scores among overweight and obese (body mass index 25.0-49.9 kg/m(2)) adults randomized to receive dietary instruction on a vegan (n = 12), vegetarian (n = 13), pescovegetarian (n = 13), semivegetarian (n = 13), or omnivorous (n = 12) diet during a 6-month randomized controlled trial. Nutrient intake, nutrient adequacy, and DII score were assessed via two 24-hour dietary recalls (Automated Self-Administered 24-Hour Dietary Recall) at baseline and at 2 and 6 months. Differences in nutrient intake and the DII were examined using general linear models with follow-up tests at each time point. We hypothesized that individuals randomized to the vegan diet would have lower DII scores and greater improvements in fiber, carbohydrate, fat, saturated fat, and cholesterol at both 2 and 6 months as compared with the other 4 diets. Participants randomized to the vegan diet had significantly greater changes in most macronutrients at both time points, including fat and saturated fat, as well as cholesterol and, at 2 months, fiber, as compared with most of the other diet groups (Ps < .05). Vegan, vegetarian, and pescovegetarian participants all saw significant improvements in the DII score as compared with semivegetarian participants at 2 months (Ps < .05) with no differences at 6 months. Given the greater impact on macronutrients and the DII during the short term, finding ways to provide support for adoption and maintenance of plant-based dietary approaches, such as vegan and vegetarian diets, should be given consideration.

Shiftwork Duration and the Awakening Cortisol Response Among Police Officers

Police officers are required to work irregular hours, which induces stress, fatigue, and sleep disruption, and they have higher rates of chronic disease and mortality. Cortisol is a well-known “stress hormone” produced via activation of the hypothalamic-pituitary-adrenal axis. An abnormal secretion pattern has been associated with immune system dysregulation and may serve as an early indicator of disease risk. This study examined the effects of long- and short-term shiftwork on the cortisol awakening response among officers (n = 68) in the Buffalo Cardio-Metabolic Occupational Police Stress (BCOPS) pilot study (2001–2003). The time each officer spent on day (start time: 04:00–11:59 h), afternoon (12:00–19:59 h), or night (20:00–03:59 h) shifts was summarized from 1994 to examination date to characterize long-term (mean: 14 ± 9 yrs) and short-term (3, 5, 7, or 14 days prior to participation) shiftwork exposures. The cortisol awakening response was characterized by summarizing the area under the curve (AUC) for samples collected on first awakening, and at 15-, 30-, and 45-min intervals after waking. Data were collected on a scheduled training or off day. The cortisol AUC with respect to ground (AUCG) summarized total cortisol output after waking, and the cortisol AUC with respect to increase (AUCI) characterized the waking cortisol response. Officers also completed the Center for Epidemiologic Studies Depression scale. Waking cortisol AUC values were lower among officers working short-term night or afternoon shifts than day shifts, with maximal differences occurring after 5 days of shiftwork. The duration of long-term shiftwork was not associated with the cortisol awakening response, although values were attenuated among officers with more career shift changes. (Author correspondence: burch@mailbox.sc.edu)

Prospective association between the dietary inflammatory index and metabolic syndrome: Findings from the SU.VI.MAX study

BACKGROUND AND AIMS The prevention of the metabolic syndrome (MetS) is of major concern and nutrition has been shown to modulate at least partly MetS risk. Our objective was to investigate whether a pro-inflammatory diet was associated with a higher risk of MetS and its components in a large cohort of French adults. METHODS AND RESULTS A total of 3726 participants from the Supplémentation en Vitamines et Minéraux AntioXydants (SU.VI.MAX) cohort were included in this study. The MetS status was identified at baseline and after 13 years of follow-up using self-reported medication, data from clinical investigations and biological measurements. The dietary inflammatory index (DII) was computed using repeated 24 h-dietary records (n = 10.1 ± 3.1). Logistic and linear regression analyses were conducted to assess the prospective association of the DII (as Q, quartiles) with the incidence of MetS and with the traits contributing to the MetS-definition (blood pressure, glycaemia, triglycerides, HDL-cholesterol, waist circumference). A diet with pro-inflammatory properties, as expressed by higher DII scores, was significantly associated with a higher risk of developing the MetS (OR comparing Q4 to Q1: 1.39, 95% confidence interval 1.01-1.92, P = 0.047). Moreover, higher DII scores were associated with higher systolic and diastolic blood pressure (Ptrend across quartiles = 0.03 and 0.05, respectively) and triglycerides (Ptrend = 0.01), and with lower HDL-cholesterol (Ptrend = 0.03). CONCLUSION A higher DII score was prospectively associated with a higher risk of MetS, with associations with blood pressure, triglycerides and HDL-cholesterol. Promotion of a healthy diet exhibiting anti-inflammatory properties may contribute to prevent cardio-metabolic disorders.

Construct validation of the Dietary Inflammatory Index among African Americans

ObjectiveChronic inflammation is linked to many chronic conditions. One of the strongest modulators of chronic inflammation is diet. The Dietary Inflammatory Index (DII) measures dietary inflammatory potential and has been validated previously, but not among African Americans (AAs).DesignCross-sectional analysis using baseline data from the Healthy Eating and Active Living in the Spirit (HEALS) intervention study.SettingBaseline data collection occurred between 2009 and 2012 in or near Columbia, SC.ParticipantsAfrican-American churchgoers.MeasurementsBaseline data collection included c-reactive protein (CRP) and interleukin-6 from blood draws, anthropometric measures, and numerous questionnaires. The questionnaires included a food frequency questionnaire which was used for DII calculation. The main analyses were performed using quantile regression.ResultsSubjects in the highest DII quartile (i.e., more pro-inflammatory) were younger, more likely to be married, and had less education and greater BMI. Individuals in DII quartile 4 had statistically significantly greater CRP at the 75th and 90th percentiles of CRP versus those in quartile 1 (i.e., more anti-inflammatory).ConclusionConstruct validation provides support for using the DII in research among AA populations. Future research should explore avenues to promote more anti-inflammatory diets, with use of the DII, among AA populations to reduce risk of chronic disease.

Association between previously diagnosed circulatory conditions and a dietary inflammatory index

Inflammation is a key contributor to the development or recurrence of circulatory disorders. Diet is a strong modifier of inflammation. It was hypothesized that more pro-inflammatory diets, as indicated by higher Dietary Inflammatory Index (DII) scores, would be associated with self-reported previously diagnosed circulatory disorders using National Health and Nutrition Examination Survey (NHANES) data. This analysis included NHANES respondents from 2005-2010 (n = 15,693). The DII was calculated from micro and macronutrients derived from a single 24-hour recall. Logistic regression, stratified by sex and adjusted for important covariates, was used to determine the odds of previous circulatory disorder diagnoses by quartile of DII scores. Excluding hypertension, which had a prevalence of 30%, the prevalence of any circulatory disorder was 8%. Those in DII quartile 4 were 1.30 (95%CI = 1.06-1.58) times more likely to have a previous circulatory disorder (excluding hypertension) compared to those in DII quartile 1. Similar findings were observed for specific CVDs including congestive heart failure, stroke, and heart attack. Participants in DII quartile 4 were more likely to have a diagnosis of hypertension compared to those in DII quartile 1 (prevalence odds ratio = 1.19, 95%CI = 1.05-1.34). Results tended to be stronger among females. Individuals with a previous circulatory disorder diagnosis from NHANES appear to have more pro-inflammatory diets compared to those without a previous diagnosis. Because inflammation is an important factor related to recurrence of circulatory disorders, the DII could be used in treatment programs to monitor dietary modulators of inflammation among individuals with these conditions.

Prospective association between the Dietary Inflammatory Index and mortality: modulation by antioxidant supplementation in the SU.VI.MAX randomized controlled trial

BACKGROUND Chronic inflammation is a central mechanism involved in cardiovascular diseases, cancer, diabetes, and chronic respiratory diseases, 4 leading causes of mortality. Diet is a major source of pro- and anti-inflammatory bioactive compounds. The Dietary Inflammatory Index (DII) was designed to estimate the overall inflammatory potential of the diet. OBJECTIVE Our aim was to study the prospective association between the DII and mortality, as well as assess whether antioxidant supplementation could modulate this association. DESIGN The Supplémentation en Vitamines et Minéraux Antioxydants study was a randomized, double-blind, placebo-controlled trial in which participants received low-dose antioxidants or a placebo from 1994 to 2002. In this observational prospective analysis, 8089 participants (mean ± SD age at baseline: 49.0 ± 6.3 y) were followed between 1994 and 2007 (median: 12.4 y). The DII was calculated from repeated 24-h dietary records; higher scores correspond to more proinflammatory diets. A total of 207 deaths occurred during follow-up, including 123 due to cancer and 41 due to cardiovascular events. Multivariate Cox proportional hazards models were computed. RESULTS Sex-specific tertiles of the DII were positively associated with cardiovascular + cancer mortality (HR for tertile 3 compared with tertile 1 = 1.53; 95% CI: 1.01, 2.32; P-trend = 0.05) and specific cancer mortality (HR for tertile 3 compared with tertile 1 = 1.83; 95% CI: 1.12, 2.99; P-trend = 0.02). The corresponding P value was 0.07 for all-cause mortality. The DII was statistically significantly associated with increased all-cause mortality in the placebo group (HR for tertile 3 compared with tertile 1 = 2.10; 95% CI: 1.15, 3.84; P-trend = 0.02) but not in the antioxidant-supplemented group (P-trend = 0.8; P-interaction = 0.098). CONCLUSION These results suggest that a proinflammatory diet is associated with increased all-cause and cancer mortality and antioxidants may counteract some of the proinflammatory effects of the diet. This trial was registered at clinicaltrials.gov as NCT00272428.

Prospective Association Between the Dietary Inflammatory Index and Cardiovascular Diseases in the SUpplémentation en VItamines et Minéraux AntioXydants (SU.VI.MAX) Cohort

Background Cardiovascular diseases (CVD) are the leading cause of death in the world, and diet plays a major role in CVD incidence, especially through lipid oxidation mechanisms. This, in turn, leads to tissue inflammation and formation of atheromatous plaques. Methods and Results Our objective was to evaluate the association between the inflammatory potential of the diet and the incidence of overall CVD or its subclasses. We included 7743 participants from the Supplémentation en Vitamines et Minéraux AntioXydants (SU.VI.MAX) cohort. All cardiovascular events were recorded using self‐reported information or clinical visits, and were validated. The dietary inflammatory index (DII) was computed using repeated 24‐hour dietary records (mean=9.5±3.4 records/subject). Hazard ratio and 95% CI for outcomes (CVD and subclasses) were estimated across sex‐specific quartiles of the DII using Cox proportional hazard models. A total of 292 cardiovascular events were recorded and validated during an average of 11.4 years of follow‐up: 93 myocardial infarctions, 58 strokes, 128 angina pectoris and revascularization interventions, and 13 sudden deaths. When considering CVD subclasses, a diet with pro‐inflammatory properties, as expressed by higher DII scores, was significantly associated with a higher risk of myocardial infarction (hazard ratioQuartile 4 versus Quartile 1=2.24, 95% CI: 1.08–4.67). No significant association was observed between the DII score and stroke or both angina pectoris and revascularization intervention. Conclusions A pro‐inflammatory diet, as measured by a higher DII score, was prospectively associated with a higher risk of myocardial infarction. Promotion of a diet exhibiting anti‐inflammatory properties may help prevent myocardial infarctions.

The Dietary Inflammatory Index Is Associated with Colorectal Cancer Risk in the Multiethnic Cohort

Background: Diet is known to influence systemic inflammation, a recognized risk factor for colorectal cancer (CRC). Studies in ethnically diverse populations that examine the association between dietary inflammatory potential and CRC incidence are limited.Objectives: We used the Dietary Inflammatory Index to clarify the relation between the inflammatory potential of diet and CRC incidence across racial/ethnic groups. We hypothesized that proinflammatory diets would be associated with an increased risk of CRC, and that these associations may differ across racial/ethnic groups.Methods: The Multiethnic Cohort (MEC) follows a prospective study design. It includes 190,963 white, African-American, native Hawaiian, Japanese-American, and Latino men and women aged 45-75 y at recruitment and followed over 20 y. Participants completed a food frequency questionnaire from which energy-adjusted Dietary Inflammatory Index (E-DII) scores were computed and categorized into quartiles. CRC incidence was documented through linkage to cancer registry programs. Cox proportional hazards regression was used to estimate HRs and 95% CIs, adjusting for known or expected CRC risk factors.Results: Among all participants, more-proinflammatory diets (highest quartile compared with lowest quartile) were associated with an increased risk of CRC (HR: 1.21; 95% CI: 1.11, 1.32). However, the effect size was larger for men (HR: 1.28; 95% CI: 1.13, 1.45) than for women (HR: 1.16; 95% CI: 1.02, 1.33), although the interaction term for sex was not statistically significant (P-interaction = 0.17). When stratified by race/ethnicity, the association was significantly different between groups for men (P-interaction = 0.01), although not for women (P-interaction = 0.20). Significant associations with HRs ranging from 2.33 to 1.04 were observed in white, Japanese-American, and Latino men, and native Hawaiian women.Conclusions: Overall, more-proinflammatory diets, as identified by the E-DII, were associated with increased CRC risk in MEC participants across racial/ethnic groups. This study adds to the evidence suggesting that diets with high proinflammatory potential may increase CRC risk.