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

Abstract

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.

Keywords: BMI; Dietary Inflammatory Index; Dietary habits; Inflammation potential; Plant-based diet.