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

BACKGROUND: 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).

METHODS: 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.

RESULTS: 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).

CONCLUSION: 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.