European Journal of Cardiovascular Medicine

Cardiovascular diseases (CVDs) remain the leading cause of morbidity and mortality worldwide, accounting for nearly 31% of global deaths ^[1]. Lifestyle factors, particularly diet, play a crucial role in the development and progression of cardiovascular health. Dietary patterns significantly influence the risk factors such as blood lipid levels, blood pressure, inflammatory markers, and oxidative stress, which are integral to cardiovascular pathophysiology ^[2]. Among dietary patterns, vegetarian and non-vegetarian diets have gained significant attention for their divergent impacts on cardiovascular health.

A vegetarian diet, characterized primarily by the exclusion of meat and sometimes other animal products, emphasizes consumption of fruits, vegetables, legumes, whole grains, nuts, and seeds. Several epidemiological studies suggest that vegetarian diets are associated with a reduced risk of CVD, lower levels of low-density lipoprotein cholesterol (LDL-C), reduced blood pressure, and improved endothelial function ^[3]. The beneficial effects of vegetarian diets are often attributed to their high fiber content, antioxidant levels, and lower saturated fat intake. In contrast, non-vegetarian diets, especially those rich in red and processed meats, have been linked to elevated cholesterol, increased oxidative stress, and inflammation, all contributing to atherosclerosis and coronary artery disease ^[4].

Blood biomarkers serve as valuable tools to assess the cardiovascular risk profile of individuals by providing measurable indices of lipid metabolism, inflammation, and endothelial function. Key biomarkers include lipid parameters like total cholesterol, LDL cholesterol, high-density lipoprotein cholesterol (HDL-C), triglycerides, and inflammatory markers such as C-reactive protein (CRP). Emerging markers like homocysteine, fibrinogen, and lipoprotein(a) further refine cardiovascular risk prediction ^[5]. The modulation of these biomarkers by diet is a critical area of research, as it may offer insights into preventive strategies for CVD.

Previous comparative studies have demonstrated favorable lipid profiles in vegetarians compared to non-vegetarians, including lower LDL-C and triglyceride levels and higher HDL-C levels [6]. However, some studies also report potential nutritional deficiencies in vegetarians, such as lower levels of vitamin B12 and omega-3 fatty acids, which could counterbalance cardiovascular benefits if not properly managed ^[7]. Moreover, inflammatory and oxidative stress markers have shown inconsistent results, underscoring the need for further well-designed comparative studies.

Framingham Risk Score: A clinical tool used to estimate an individual's 10-year risk of developing cardiovascular disease based on factors such as age, gender, cholesterol levels, blood pressure, smoking status, and diabetes.

Metabolic Syndrome: A cluster of metabolic abnormalities—including abdominal obesity, high blood pressure, elevated blood sugar, high triglycerides, and low HDL cholesterol—that together increase the risk of cardiovascular disease and type 2 diabetes.

Aim

To compare blood biomarkers associated with cardiovascular health in individuals adhering to vegetarian versus non-vegetarian diets.

Objectives

1. To evaluate and compare lipid profiles including total cholesterol, LDL-C, HDL-C, and triglycerides between vegetarian and non-vegetarian adults.
2. To assess inflammatory biomarkers such as C-reactive protein (CRP) and homocysteine levels in the two dietary groups.
3. To analyze the overall implications of dietary patterns on cardiovascular risk based on the biomarker profiles.

Source of Data: The data for this cross-sectional study were obtained from adult volunteers attending outpatient departments and health screening camps in tertiary care hospitals and community health centers within the study location. Participants were recruited via purposive sampling after screening for eligibility criteria.

Study Design: This was a cross-sectional, comparative observational study designed to assess and compare blood biomarkers related to cardiovascular health between two dietary groups: vegetarians and non-vegetarians.

Study Location: The study was conducted at the Department of Biochemistry at tertiary care hospital.

Study Duration: Data collection occurred over a period of 11 months from January 2024 to November 2024.

Sample Size: The study included a total of 140 adult participants, with 70 vegetarians and 70 non-vegetarians matched for age and sex to reduce confounding effects.

Inclusion Criteria:

• Adults aged 25 to 60 years.
• Individuals adhering strictly to vegetarian or non-vegetarian diets for at least 2 years.
• Willingness to provide informed consent for blood sample collection and participation.

Exclusion Criteria:

• Individuals with diagnosed cardiovascular diseases, diabetes mellitus, chronic kidney or liver disease.
• Those on lipid-lowering, anti-inflammatory, or antioxidant medications.
• Pregnant or lactating women.
• Individuals with acute infections or inflammatory conditions at the time of study.

Procedure and Methodology: Participants were interviewed to obtain detailed dietary histories, including duration and type of diet (vegetarian or non-vegetarian). Anthropometric measurements such as height, weight, and body mass index (BMI) were recorded. Blood pressure was measured using a calibrated sphygmomanometer following standard guidelines.

After overnight fasting (8-12 hours), 5 ml of venous blood was drawn from the antecubital vein under aseptic conditions. Samples were collected in plain and EDTA vacutainers for biochemical analysis.

Sample Processing: Blood samples were centrifuged at 3000 rpm for 10 minutes to separate serum. Serum was aliquoted and stored at -20°C until analysis. All biochemical assays were performed wiin one week of collection to ensure sample integrity.

Lipid profile parameters (total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides) were measured using enzymatic colorimetric methods on an automated analyzer. High-sensitivity C-reactive protein (hs-CRP) levels were measured using immunoturbidimetric assay. Homocysteine levels were determined by enzyme-linked immunosorbent assay (ELISA).

Quality control procedures included running internal controls and calibrators as per manufacturer instructions. All assays were conducted in duplicate to improve reliability.

Statistical Methods: Data were entered and analyzed using Statistical Package for Social Sciences (SPSS) version 25.0. Descriptive statistics included means, standard deviations, and proportions. The normality of data distribution was checked using the Shapiro-Wilk test.

Comparisons between vegetarian and non-vegetarian groups were performed using independent sample t-tests for normally distributed continuous variables and Mann-Whitney U tests for non-parametric variables. Chi-square tests were used for categorical variables. Correlation analyses were done using Pearson’s or Spearman’s correlation coefficients where applicable.

A p-value of <0.05 was considered statistically significant.

Data Collection: Data were collected using a structured proforma that recorded demographic details, dietary habits, medical history, anthropometric data, and laboratory results. Confidentiality was maintained throughout the study, and participants were assigned unique identifiers to protect privacy.

Table 1: Baseline Demographic and Clinical Characteristics of Study Participants (n=140)

The baseline demographic and clinical characteristics of the 140 study participants, equally divided between vegetarians and non-vegetarians (70 each), are summarized in Table 1. The mean age of vegetarians was 42.6 ± 10.3 years, compared to 44.2 ± 9.7 years in non-vegetarians, with no significant difference observed (t = 1.07, p = 0.29). The proportion of males was similar between the groups (54.3% in vegetarians versus 58.6% in non-vegetarians; χ² = 0.29, p = 0.59). However, significant differences were noted in body mass index (BMI), where vegetarians had a significantly lower mean BMI (23.9 ± 3.1 kg/m²) compared to non-vegetarians (26.3 ± 3.7 kg/m²) (t = 4.85, p < 0.001). Smoking prevalence was also significantly lower among vegetarians, with only 4.3% current smokers compared to 20.0% in non-vegetarians (χ² = 9.43, p = 0.002). Although hypertension was more prevalent in non-vegetarians (22.9%) than vegetarians (11.4%), this difference was not statistically significant (χ² = 3.24, p = 0.07). Regular physical activity was reported by 64.3% of vegetarians and 55.7% of non-vegetarians, but this difference did not reach statistical significance (χ² = 1.15, p = 0.28).

Table 2: Lipid Profile Comparison Between Vegetarian and Non-Vegetarian Adults (n=140)

Table 2 presents the lipid profile comparison between the two dietary groups. Vegetarians exhibited significantly lower mean total cholesterol levels (172.4 ± 32.5 mg/dL) compared to non-vegetarians (194.7 ± 40.8 mg/dL), with a highly significant difference (t = 3.98, p < 0.001). Similarly, LDL cholesterol was significantly lower in vegetarians (101.8 ± 26.1 mg/dL) than non-vegetarians (123.2 ± 30.3 mg/dL) (t = 4.36, p < 0.001). Conversely, HDL cholesterol was significantly higher in vegetarians (52.6 ± 11.2 mg/dL) compared to non-vegetarians (44.9 ± 10.9 mg/dL) (t = 4.28, p < 0.001). Triglyceride levels were also significantly lower in vegetarians (115.7 ± 37.3 mg/dL) compared to non-vegetarians (141.9 ± 48.6 mg/dL) (t = 3.54, p = 0.0005).

Table 3: Inflammatory Biomarkers Comparison (n=140)

Inflammatory biomarker levels, as shown in Table 3, differed markedly between the groups. High-sensitivity C-reactive protein (hs-CRP) levels were significantly lower in vegetarians (1.72 ± 0.85 mg/L) compared to non-vegetarians (3.15 ± 1.45 mg/L) (t = 8.25, p < 0.001). Similarly, homocysteine concentrations were significantly reduced in vegetarians (8.95 ± 2.76 µmol/L) relative to non-vegetarians (11.30 ± 3.12 µmol/L) (t = 5.97, p < 0.001), indicating a lower systemic inflammatory and cardiovascular risk profile in the vegetarian group.

Table 4: Cardiovascular Risk Indicators Based on Biomarker Profiles (n=140)

Table 4 summarizes cardiovascular risk indicators derived from biomarker profiles. The Framingham Risk Score, estimating 10-year cardiovascular risk, was significantly lower in vegetarians (6.8 ± 2.5%) than in non-vegetarians (10.4 ± 3.7%) (t = 7.34, p < 0.001). Both systolic and diastolic blood pressures were significantly reduced in vegetarians (118.6 ± 12.7 mmHg and 75.4 ± 8.9 mmHg, respectively) compared to non-vegetarians (126.4 ± 15.3 mmHg systolic and 81.0 ± 10.2 mmHg diastolic), with p-values of 0.0005 for each (t = 3.56). Additionally, the prevalence of metabolic syndrome was significantly lower in vegetarians (8.6%) than in non-vegetarians (21.4%) (χ² = 5.13, p = 0.023). Collectively, these findings underscore the association of vegetarian dietary patterns with a more favorable cardiovascular risk profile.

The present study compared baseline demographic, clinical, biochemical, and cardiovascular risk parameters between vegetarians and non-vegetarians, revealing several notable differences with implications for cardiovascular health.

Baseline Characteristics (Table 1): Our findings demonstrated no significant difference in mean age (42.6 vs. 44.2 years, p=0.29) or gender distribution (54.3% vs. 58.6% males, p=0.59) between vegetarians and non-vegetarians, indicating well-matched groups and reducing confounding by these factors. Similar age and sex distributions were reported by Fontes T et al.(2024)^[8], who compared cardiovascular risk markers in vegetarians versus omnivores. Importantly, vegetarians showed a significantly lower BMI (23.9 vs. 26.3 kg/m², p<0.001), consistent with multiple studies indicating lower body weight and BMI among vegetarians. Lower BMI in vegetarians may be attributable to higher fiber intake, lower saturated fat consumption, and differences in energy metabolism Robberecht H et al.(2017)^[9]. The significantly lower prevalence of current smokers among vegetarians (4.3% vs. 20.0%, p=0.002) aligns with lifestyle patterns described in other vegetarian cohorts, where smoking and other unhealthy habits are less common Nebl J et al.(2019)[10]. Though hypertension prevalence was higher in non-vegetarians (22.9% vs. 11.4%), this difference narrowly missed statistical significance (p=0.07), mirroring trends reported by Rizzo et al. who found lower hypertension rates in vegetarian populations Kim H et al.(2021)^[11]. Physical activity rates did not differ significantly, suggesting that diet rather than exercise largely explains the biomarker differences.

Lipid Profile Differences (Table 2): Vegetarians exhibited significantly lower total cholesterol (172.4 vs. 194.7 mg/dL, p<0.001) and LDL cholesterol (101.8 vs. 123.2 mg/dL, p<0.001) and higher HDL cholesterol (52.6 vs. 44.9 mg/dL, p<0.001) compared to non-vegetarians. Triglyceride levels were also significantly lower (115.7 vs. 141.9 mg/dL, p=0.0005). These results corroborate previous meta-analyses indicating favorable lipid profiles in vegetarians, which may reduce atherosclerotic risk Kumar A et al.(2022)^[12]. Lovrenčić MV et al.(2020)^[13]. similarly reported lower LDL and triglycerides with higher HDL in vegetarians, attributing benefits to reduced saturated fat and cholesterol intake and increased antioxidant consumption. These lipid alterations in vegetarians may partially explain their reduced cardiovascular morbidity and mortality observed in large cohort studies.

Inflammatory Biomarkers (Table 3): High-sensitivity CRP (hs-CRP) and homocysteine were significantly lower in vegetarians (hs-CRP: 1.72 vs. 3.15 mg/L; homocysteine: 8.95 vs. 11.30 µmol/L; both p<0.001). Elevated hs-CRP is a well-established marker of systemic inflammation and cardiovascular risk Ganie MA et al.(2019)^[14]. Lower hs-CRP in vegetarians may result from higher intake of anti-inflammatory nutrients such as fiber, polyphenols, and omega-3 fatty acids from plant sources. Homocysteine, an independent risk factor for CVD due to its pro-thrombotic and endothelial damaging effects, was also lower among vegetarians, consistent with reports by Sungheetha A et al.(2024)^[15], although some vegetarian populations may be at risk for B12 deficiency leading to hyperhomocysteinemia. Our findings suggest adequate nutritional status and cardiovascular protective effects in the vegetarian cohort.

Cardiovascular Risk Indicators (Table 4): Framingham Risk Scores were significantly lower in vegetarians (6.8% vs. 10.4%, p<0.001), reflecting reduced 10-year risk of coronary events. Blood pressure was also significantly lower among vegetarians (systolic 118.6 vs. 126.4 mmHg; diastolic 75.4 vs. 81.0 mmHg; both p=0.0005), aligning with prior research demonstrating blood pressure-lowering effects of plant-based diets Gogga P et al.(2024)^[16]. The prevalence of metabolic syndrome was markedly lower in vegetarians (8.6% vs. 21.4%, p=0.023), which is consistent with evidence that vegetarian diets favorably influence components of metabolic syndrome including insulin sensitivity, lipid metabolism, and adiposity Wang C et al.(2024)^[17].

This study demonstrates that individuals adhering to vegetarian diets exhibit significantly more favorable blood biomarker profiles related to cardiovascular health compared to non-vegetarians. Vegetarians showed lower BMI, reduced total cholesterol, LDL cholesterol, triglycerides, and inflammatory markers such as hs-CRP and homocysteine. Additionally, cardiovascular risk indicators including the Framingham Risk Score and blood pressure were significantly lower in vegetarians. These findings underscore the cardioprotective potential of vegetarian dietary patterns, likely mediated through healthier lipid profiles and reduced systemic inflammation. Encouraging plant-based dietary habits may therefore represent an effective strategy for reducing cardiovascular risk and improving population health outcomes.

LIMITATIONS OF STUDY

1. Cross-sectional Design: The observational, cross-sectional nature limits the ability to infer causality between diet type and biomarker differences.
2. Self-Reported Dietary Status: Dietary classification was based on self-report, which may introduce recall bias or misclassification.
3. Nutritional Status: The study did not measure all micronutrient levels (e.g., vitamin B12, omega-3 fatty acids) which may influence cardiovascular biomarkers.
4. Lifestyle Confounders: Although adjustments were made, residual confounding from other lifestyle factors such as stress, socioeconomic status, and unmeasured physical activity levels cannot be excluded.
5. Sample Size and Population: The sample was relatively small and regionally limited, which may affect the generalizability of findings to broader or ethnically diverse populations.
6. Single Time-Point Measurement: Biomarkers were measured only once, which may not reflect long-term dietary effects or intra-individual variability.

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