Cross-Sectional Comparison of Plant-Based and Omnivorous Diets on Cardiometabolic Risk

Thesis Abstract

Cardiometabolic disease risk remains a pressing global concern amid dietary transitions toward plant-based patterns and pervasive omnivorous consumption. This study addresses the problem of limited comparative evidence on how plant-based versus omnivorous diets relate to cardiometabolic risk markers in diverse adult populations, and whether dietary pattern breadth moderates associations with metabolic outcomes. The aim is to quantify and compare cardiometabolic risk profiles between adults adhering to plant-based diets and those consuming omnivorous diets, while controlling for confounders such as age, sex, BMI, physical activity, socioeconomic status, and dietary quality. Specific objectives are (1) to characterize diet typologies using validated food frequency questionnaires and categorize participants into plant-based and omnivorous groups; (2) to evaluate cardiometabolic biomarkers including fasting glucose, HbA1c, lipid panel (LDL-C, HDL-C, triglycerides), fasting insulin, HOMA-IR, blood pressure, and inflammatory markers (hs-CRP, IL-6); (3) to assess body composition indices via dual-energy X-ray absorptiometry (DEXA) and waist circumference; (4) to examine associations between dietary pattern and cardiometabolic risk using multivariable linear and logistic regression analyses; and (5) to explore potential mediators such as fiber intake, micronutrient adequacy, and gut microbiota proxies. The study adopts a cross-sectional design with a targeted sample of 1,200 adults aged 25–65 years recruited from urban and peri-urban health centers to ensure representation across sexes and socioeconomic strata. Data collection combines dietary assessment (validated semi-quantitative food frequency questionnaire and 24-hour recalls), anthropometry and body composition (stadiometry, DEXA), clinical measures (blood pressure using automated cuffs, resting heart rate), and venous blood draws for biochemical analyses. The analytical framework employs descriptive statistics to profile cohorts, multivariable linear regression to compare continuous cardiometabolic outcomes, and logistic regression for categorical risk thresholds (e.g., metabolic syndrome components as defined by NCEP ATP III). Model diagnostics will include assessment of collinearity, interaction terms for gender and age, and sensitivity analyses excluding participants with recent acute illnesses or medication changes. Additional analyses will use propensity score weighting to balance covariates between diet groups and multiple imputation for missing data. The theoretical underpinning integrates the Health Belief Model to interpret dietary adherence, and the Nutrition Transition theory to contextualize pattern shifts, complemented by the Dietary Patterns and Cardiometabolic Risk framework to hypothesize mechanistic pathways through fiber intake, micronutrient density, and inflammatory processes. Expected findings anticipate that plant-based dieters will exhibit more favorable lipid profiles and lower inflammatory markers, with comparable or modestly improved glycemic control, blood pressure, and central adiposity relative to omnivores after adjustment. However, heterogeneity within plant-based patterns (e.g., whole-food plant-based vs. processed plant-based diets) may modulate risk markers, highlighting the importance of diet quality beyond mere dietary category. The study aims to contribute to knowledge by providing robust cross-sectional evidence on how plant-based and omnivorous dietary patterns relate to composite cardiometabolic risk in a diverse adult population, clarifying the roles of fiber and micronutrient adequacy, and informing clinical and public health guidance on dietary pattern recommendations. The implications include refining dietary guidelines to emphasize nutrient-dense plant foods and prudent inclusion of animal-derived nutrients where appropriate, and guiding personalized nutrition interventions that target metabolic health without stigmatizing dietary choices. The main conclusion is that diet quality within each dietary pattern substantially shapes cardiometabolic risk, with whole-food plant-based patterns likely offering cardiometabolic advantages when matched by nutrient adequacy and low saturated fat intake; recommendations include promoting diverse, fiber-rich plant foods alongside targeted monitoring of lipids and glycemic markers in dietary counseling, and encouraging longitudinal follow-up studies to establish causal inferences and explore microbiome-related mediators.