Association between the Dietary Inflammatory Index (DII) and urinary enterolignans and C-reactive protein from the National Health and Nutrition Examination Survey-2003–2008

Nitin Shivappa, Michael D. Wirth, E. Angela Murphy, Thomas G. Hurley, James R. Hébert

Enterolignans are important biomarkers of microbiota diversity, with higher levels indicating greater diversity. Diet and inflammation have been shown to play a role in maintaining microbiota diversity. This study examined whether inflammatory potential of diet, as measured by the Dietary Inflammatory Index (DII®) has an impact on levels of urinary enterolignans in the National Health and Nutrition Examination Survey (NHANES) 2003-2008. We also carried out construct validation of the DII with C-reactive protein (CRP). Data came from NHANES 2003-2008. Enterolignans [enterodiol (END) and enterolactone (ENL)] and CRP were assayed from urine and serum specimens, respectively. Energy-adjusted DII (E-DII) scores were calculated from food intakes assessed using 24-h dietary recalls and expressed per 1000 calories consumed. Associations were examined using survey-based multivariable linear and logistic regression for enterolignans, and logistic regression for CRP. After multivariable adjustment, higher E-DII scores (i.e., indicating a relatively more pro-inflammatory diet) were associated with lower levels of creatinine-normalized END [beta coefficient (b)DIIquartile4vs1 = - 1.22; 95% CI = - 0.69, - 1.74; Ptrend ≤ 0.001] and ENL (bDIIquartile4vs1 = - 7.80; 95% CI = - 5.33, - 10.26; Ptrend ≤ 0.001). A positive association was also observed when enterolignans were dichotomized based on the cut-off of the 75th percentile value. In this same sample, the E-DII also was associated with CRP ≥ 3 mg/l (ORDIIcontinuous = 1.12; 95% CI 1.05, 1.19). In these NHANES data, there was an association between E-DII score and enterolignans. This study also provided construct validation of the E-DII using CRP in a nationally representative sample. The results indicate that dietary inflammatory potential is associated with urinary enterolignans, a potential marker for microbiota diversity. However, studies are required to understand the direct association between DII and microbiota.