Longitudinal changes in the dietary inflammatory index: an assessment of the inflammatory potential of diet over time in postmenopausal women

Abstract

Background/objectiveThe dietary inflammatory index (DII) measured at one time point is associated with risk of several chronic diseases but disease risk may change with longitudinal changes in DII scores. Data are lacking regarding changes in DII scores over time, therefore we assessed changes in the DII in the Women's Health Initiative (WHI).MethodsDII scores were calculated using data from repeated food frequency questionnaires in the WHI Observational Study (OS; n=76,671) at baseline and Year 3, and the WHI Dietary Modification trial (DM; n=48,482) at three time points. Lower DII scores represent more anti-inflammatory diets. We used generalized estimating equations to compare mean changes in DII over time, adjusting for multiple comparisons; and multivariable linear regression to determine predictors of DII change.ResultsIn the OS, mean DII decreased modestly from −1.14 at baseline to −1.50 at Year 3. In the DM, DII was −1.32 in Year 1, −1.60 in Year 3, and −1.48 in Year 6 in the intervention arm, and was −0.65 in Year 1, −0.94 in Year 3 and −0.96 in Year 6 in the control arm. These changes were modified by BMI, education, and race/ethnicity. A prediction model explained 22% of the variance in the change in DII scores in the OS.ConclusionIn this prospective investigation of postmenopausal women, reported dietary inflammatory potential decreased modestly over time. Largest reductions were observed in normal weight, highly educated women. Future research is warranted to examine whether reductions in DII are associated with decreased chronic disease risk.

The association between an inflammatory diet and global cognitive function and incident dementia in older women: The Women's Health Initiative Memory Study

“…We did, however, control for region in our analysis. In a subsample from the larger WHI cohort, a modest decrease in DII scores was observed over time [65]. It is likely that some of the individuals included in the group with the diet that had the highest anti-inflammatory potential were following a healthy diet due to illness.…”

Inflammatory potential of diet and risk of pancreatic cancer in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial

“…However, we previously found DII scores were relatively stable over a long timeframe in postmenopausal women who were of comparable ages as ours. 49 Another limitation of the study is that data were available on only 35 out of the 45 DII components used to calculate the E-DII scores; however, the range of DII scores may rely more on the total amount of inflammatory components actually consumed rather than the number of available DII components. 50 In many populations, omitting even 15 to 20 parameters has little effect on DII scores.…”

The Dietary Inflammatory Index and All-Cause, Cardiovascular Disease, and Cancer Mortality in the Multiethnic Cohort Study

“…The current analyses of the DII and mortality were based on a single assessment of diet at baseline. We plan to compute the DII scores for a 10-year follow-up survey, where the QFFQ would be repeated among 45% of the participants, and will be able to compare DII changes over time, as was done in the Women’s Health Initiative Observational Study and Dietary Modification trial control group [28,29]. Despite the comprehensive information on lifestyle factors and careful adjustment for covariates, there is still the possibility of residual confounding by unmeasured or incompletely controlled variables that might be related to both diet and mortality.…”