Plant-based diet quality and cardiometabolic biomarkers in pregnant U.S. women

Background: Evidence suggests that high-quality plant-based diets are associated with favorable cardiometabolic outcomes. However, there is no consensus on the optimal measure to assess the quality of plant-based diet. Furthermore, little is known about how plant-based diet quality relates to cardiometabolic health in pregnant women. Objective: Determine the relationship between plant-based diet and cardiometabolic biomarkers in pregnant women, with a specific focus on different approaches to assess plant-based diet quality. Methods: Data from 580 pregnant women who participated in seven cycles (2005 to 2020 prepandemic) of the National Health and Nutrition Examination Survey (NHANES) were used. Four previously established indices, including the overall Plant-Based Diet Index (PDI), healthful PDI (hPDI), total plant-based foods (All PBF), and Healthy PBF, were calculated. In addition, two modified indices were developed. Multivariable log-linear regression models were used to assess associations between these indices and cardiometabolic biomarkers. Results: Higher plant-based diet quality index values, independent of the index used, were positively associated with high-density lipoprotein cholesterol (HDL-C) concentrations, and negatively associated with triglyceride (TG)/HDL-C ratios. Each one-point increase in the diet index was associated with a 0.004 to 0.016 mg/dL increase in HDL-C and 0.018 to 0.031 decrease in TG/HDL-C ratio. Additionally, those indices that accounted for plant foods quality were also associated with lower fasting insulin and TG concentrations, and homeostatic model assessment for insulin resistance (HOMA-IR). Conclusions: In this NHANES cohort of pregnant women, higher values of all plant-based diet indices were associated with more favorable biomarkers of cardiometabolic health. Those plant-based diet indices that emphasized the quality of plant foods rather than penalizing the inclusion of animal foods were more strongly associated with cardiometabolic health biomarkers.