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A population-based dietary inflammatory index predicts levels of C-reactive protein in the Seasonal Variation of Blood Cholesterol Study (SEASONS)

Shivappa, Nitin, Steck, Susan E, Hurley, Thomas G, Hussey, James R, Ma, Yunsheng, Ockene, Ira S, Tabung, Fred, Hébert, James R
Public health nutrition 2014 v.17 no.8 pp. 1825-1833
C-reactive protein, blood serum, cholesterol, clinical trials, diet recall, foods, observational studies, questionnaires, regression analysis, seasonal variation, Massachusetts
To perform construct validation of the population-based Dietary Inflammatory Index (DII) using dietary data from two different dietary assessments and serum high-sensitivity C-reactive protein (hs-CRP) as the construct validator. Using data derived from (i) three 24 h dietary recalls (24HR) at baseline and at the end of each subsequent quarter (i.e. up to fifteen over a year) and (ii) a 7 d dietary recall (7DDR) measured at baseline and then quarterly, regression analyses were conducted to test the effect of the DII score on serum hs-CRP as dichotomous (≤3 mg/l, >3 mg/l), while controlling for important potential confounders. Existing data from the Seasonal Variation of Blood Cholesterol Study (SEASONS), a longitudinal observational study of healthy participants recruited in Worcester, MA, USA and participants were followed for 1 year. Participants who had at least one hs-CRP measurement over her/his 1-year participation (n 495 for 24HR, n 559 for 7DDR). Higher DII scores were associated with values of hs-CRP >3 mg/l (OR = 1·08; 95 % CI 1·01, 1·16, P = 0·035 for the 24HR; and OR = 1·10; 95 % CI 1·02, 1·19, P = 0·015 for the 7DDR). The population-based DII was associated with interval changes in hs-CRP using both the 24HR and 7DDR. The success of this first-of-a-kind attempt at relating individuals’ intakes of inflammation-modulating foods using this refined DII, and the finding that there is virtually no drop-off in predictive capability using a structured questionnaire in comparison to the 24HR standard, sets the stage for use of the DII in a wide variety of other epidemiological and clinical studies.