Associations Among Plant-Based Dietary Indexes, the Dietary Inflammatory Index, and Inflammatory Potential in Female College Students In Saudi Arabia: A Cross-Sectional Study

Background Saudi Arabian diets are transitioning to more Western dietary patterns that have been associated with higher levels of inflammation. Emerging evidence suggests plant-based diets are related to lower levels of inflammation; however, the definition of plant-based diets varies. Objective The purpose of this study was to identify the extent to which an overall Plant-Based Diet Index (PDI), Healthy-PDI (hPDI), and Unhealthy-PDI (uPDI) vs Energy Adjusted Dietary Inflammatory Index correlate with high-sensitivity C-reactive protein (hs-CRP) level. Design This was a cross-sectional study carried out at King Saud University. Data on dietary intake, anthropometrics, and hs-CRP were collected. Participants/setting Female students aged 19 to 35 years (n = 401) were recruited from King Saud University, Riyadh, Saudi Arabia, between February and May 2019. Main outcome measures The main outcome was hs-CRP level. Statistical analyses performed Pearson correlation and multivariate linear regression analyses were used to examine the associations between hs-CRP, each PDI, and Energy Adjusted Dietary Inflammatory Index (E-DII). Results E-DII and uPDI scores had a moderate and a small positive correlation with hs-CRP levels (r = 0.46 and 0.22, respectively), whereas PDI and hPDI scores had a small and a moderate inverse correlation with hs-CRP levels (r = 0.13 and -0.31, respectively). A 1-standard deviation higher E-DII score was directly associated with a 1.05 mg/L higher hs-CRP level (95% confidence interval 0.72 to 1.38; P <= 0.0001) after adjusting for body mass index. Overall PDI score was not associated with hs-CRP levels. A 6-point higher hPDI and uPDI score were associated with a 0.13 mg/L lower hs-CRP (95% confidence interval -0.08 to 0.28) and a 0.15 mg/L higher hs-CRP (95% confidence interval 0.03 to 0.31), respectively, after adjusting for lifestyle and dietary factors; however, results attenuated and were no longer statistically significant after body mass index adjustment. Conclusions Although all indexes had a small or moderate correlation with hs-CRP, only E-DII score was positively associated with hs-CRP level. Future research can examine PDI-based interventions for lowering inflammation.