Abstract
Background
Vegetarian or vegan diets have been associated with favorable cardiovascular outcomes in the general population; however, their effects on cardiometabolic risk factors in patients with established cardiovascular disease (CVD) remain unclear. This systematic review and meta-analysis aimed to evaluate the effects of vegetarian or vegan dietary interventions on cardiometabolic risk factors in patients with CVD.
Methods
A systematic search of five electronic databases was conducted from inception to January 1, 2026. Randomized controlled trials (RCTs) comparing vegetarian or vegan diets with omnivorous diets in adult patients with CVD were included. Outcomes of interest included systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG). Pooled mean differences (MDs) with 95% confidence intervals (CIs) were calculated using fixed- or random-effects models according to heterogeneity. Subgroup and sensitivity analyses were performed to explore potential sources of heterogeneity.
Results
Six RCTs involving 325 patients with CVD were included. Compared with omnivorous diets, vegetarian or vegan diets were associated with significant reductions in TC [MD = -0.63 mmol/L (95%CI [-1.20, -0.05], P = 0.030)] and LDL-C [MD = -0.56 mmol/L (95%CI [-1.09, -0.02], P = 0.041)], but also with a modest reduction in HDL-C [MD = -0.05 mmol/L (95%CI [-0.10, -0.01], P = 0.023)]. No significant effects were observed on SBP, DBP, or TG levels. Subgroup analyses indicated that low-fat vegan diets, intervention duration, age, and BMI influenced lipid outcomes. Greater reductions in TC were observed in patients aged ≤ 60 years and those with BMI < 30, whereas LDL-C reductions were more pronounced in patients aged ≤ 60 years and those with BMI ≥ 30.
Conclusions
Vegetarian or vegan diets, particularly low-fat vegan diets, may improve lipid profiles by reducing TC and LDL-C in patients with established CVD. No significant benefits were observed for blood pressure or triglycerides. These findings suggest that plant-based dietary interventions may serve as a complementary strategy for the management of cardiometabolic risk factors in CVD patients.
Trial registration
The study protocol has been registered with PROSPERO under the registration number: CRD420261283606.
Supplementary Information
The online version contains supplementary material available at https://doi.org/10.1186/s12937-026-01373-z.
Keywords: Vegan diet, Vegetarian, Cardiovascular diseases, Cardiometabolic risk factors, Meta-analysis
Background
Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality worldwide, accounting for a substantial proportion of global deaths and health care burden despite advances in medical therapy and prevention strategies [1, 2]. Unhealthy dietary patterns, characterized by high intake of saturated fats, processed meats, and refined carbohydrates, are well-established modifiable risk factors for the development and progression of CVD and associated metabolic dysfunctions such as dyslipidemia, hypertension, and obesity [3]. In contrast, plant-based dietary patterns, including vegetarian and vegan diets, have attracted significant scientific interest due to their nutrient profile, which is typically high in dietary fiber, antioxidants, unsaturated fats, and phytochemicals, and lower in saturated fats and dietary cholesterol [4, 5]. Such diets may favorably influence cardiometabolic risk factors and consequently reduce CVD risk.
Observational studies and meta-analyses suggested that adherence to vegetarian or vegan diets is associated with a lower incidence of CVD and ischemic heart disease compared with non-vegetarian diets [6, 7]. Beyond effects on disease incidence, evidence from interventional studies suggests that plant-based diets may favorably influence cardiometabolic biomarkers. Vegetarian dietary interventions have been associated with reductions in low-density lipoprotein cholesterol (LDL-C), glycated hemoglobin, and body weight among individuals with or at high risk of cardiovascular disease, providing insight into potential cardioprotective mechanisms [8]. Similarly, evidence from meta-analyses of blood lipid outcomes suggests that vegetarian and vegan diets, compared with omnivorous diets, are associated with lower levels of total cholesterol and LDL-C, both of which are major contributors to atherosclerotic cardiovascular risk [9]. Despite this growing body of evidence, the cardiometabolic effects of vegetarian and vegan diets, specifically in patients with established CVD, have not been comprehensively synthesized. While many studies have explored dietary effects in general or high-risk populations, fewer investigations focus on individuals with diagnosed CVD, and results are variable across outcomes such as blood lipids, glycemic control, and other metabolic risk factors [10, 11]. Therefore, there is a need for a systematic review and meta-analysis to elucidate the effects of vegetarian or vegan diets on cardiometabolic risk factors in patients with CVD.
Accordingly, this systematic review and meta-analysis aim to comprehensively synthesize the current evidence on the effects of vegetarian and vegan diets on cardiovascular metabolic health in patients with established CVD, thereby providing a more robust evidence base to inform dietary recommendations and clinical practice.
Materials and methods
Protocol and search strategy
This systematic review and meta-analysis were performed in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines [12]. The study protocol has been registered with PROSPERO under the registration number: CRD420261283606.
PubMed, Scopus, Web of Science, Embase, and Cochrane Library databases were searched to identify relevant studies published up to January 1st, 2026. The relevant search strategy used various combinations of predefined search terms related to vegetarian or vegan diet and CVD, as well as Boolean search terms (AND, OR, and NOT). Details of the search strategy are shown in supplementary Table 1. In addition, the bibliographies of the included studies and related reviews were manually scrutinized to ensure a comprehensive literature search. The literature search was independently conducted by SKW and HL. Any disagreements were resolved through discussion or consultation with a third reviewer.
Inclusion and exclusion criteria
Inclusion criteria included: (1) Participants were adults with CVD (age ≥ 18 years old). (2) Participants included in the study were undergoing a vegetarian or vegan diet, and the control group followed an omnivorous diet. (3) The outcomes of the study include levels of cardiac metabolic risk factors in CVD patients (including systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides). (4) Studies were designed as randomized controlled trials (RCTs). (5) Studies were published in English.
Exclusion criteria included: (1) Participants were not adults or were pregnant. (2) Animal studies. (3) Observational studies, notes, letters, comments, case reports, and conference abstracts.
Data extraction process
Data extraction was independently performed by SKW and CHH. In case of disagreement, a third author was consulted to resolve it. The following data were extracted from the included studies: the first author, year of publication, country/region, participants’ characteristics, sample size, mean/median age of participants, gender (proportion of males), baseline mean body mass index (BMI), intervention and control diet, intervention duration, and primary outcomes.
Dietary classification
Vegetarian and vegan dietary interventions were categorized into two groups-low-fat vegan diets and lacto-vegetarian diets-according to the definitions provided in the original studies. “Low-fat vegan diets” were defined as dietary interventions excluding all animal-derived foods, including meat, fish, dairy products, and eggs. Because the specific fat restrictions varied across studies, the classification of “low-fat vegan diet” was based on the definitions reported in the original trials. “Lacto-vegetarian diets” referred to vegetarian dietary patterns that included dairy products while excluding eggs and meat products.
Risk of bias assessment
The Risk of Bias for Randomized Trials tool (RoB 2.0) [13] was used to evaluate the risk of bias in randomized trials, focusing on five components: the randomization process, deviations from the intended intervention, missing outcome data, outcome measurements, and reporting options. Outcomes of bias assessment were categorized as being rated as low risk, some problems, or high risk. According to the RoB 2.0 guidance, studies were judged as “low risk” when all assessed domains were rated as low risk of bias, “some concerns” when at least one domain raised some concerns without being classified as high risk, and “high risk” when at least one domain was rated as high risk of bias or when multiple domains raised concerns that could substantially reduce confidence in the study findings. Two investigators (SKW and HL) independently reviewed the quality of the study, and any disagreements between investigators were resolved by consensus or third-party consultation.
Statistical analyses
Statistical analyses were conducted using Stata software (version 14.0 SE; Stata Corp LP, College Station, TX, USA) and Review Manager (Version 5.3. Cochrane Collaboration, Oxford, England). Effect sizes were expressed as mean differences (MDs) with corresponding 95% confidence intervals (CIs), which were calculated based on reported means and standard deviations (SDs). A fixed-effects model was applied when heterogeneity was not significant, whereas a random-effects model was adopted in the presence of substantial heterogeneity (P < 0.10 or I² >50%) [14]. Subgroup analyses were performed to explore potential sources of heterogeneity, including vegetarian diet type, intervention duration, participants’ age, and BMI. Sensitivity analyses were conducted to examine the robustness of the pooled results by assessing the influence of individual studies on the overall effect estimates. Publication bias was evaluated using funnel plots and Egger’s linear regression test. Statistical significance was set at P-value < 0.05.
Results
Literature search and selection
An initial systematic search yielded 10,475 studies from online databases, complemented by eight additional studies identified through manual searches. After manually removing duplicates, a total of 6,604 articles were screened. Title and abstract screening excluded 6,574 articles due to non-adult participants; irrelevance; non-RCT designs; or being conference abstracts, summaries, letters, or comments. Full-text evaluation of 31 articles led to the exclusion of 25 for reasons including non-adult participants (n = 1); non-vegetarian (n = 5); irrelevant outcomes (n = 7); non-English language (n = 4); and non-RCT design (n = 8). Finally, six articles [15–20] were included in this systematic review and meta-analysis. The detailed literature retrieval process is shown in Fig. 1.
Fig. 1.
Flow diagram of included studies selection process
Characteristics of the included studies
Six studies involving 325 CVD patients, published between 1990 and 2020, were included in the meta-analysis. Sample sizes ranged from 25 to 100, with participant mean/median ages from 55.4 to 67.0 years, and the proportion of males ranged from 57.0% to 100%. Four studies [15, 17–19] implemented a low-fat vegan diet, while the other two [16, 20] adopted a lacto-vegetarian diet. The intervention duration ranged from four weeks to 48 weeks, with BMI ranging from 27.1 to 32.0 kg/m2. Detailed study information is presented in Table 1.
Table 1.
Main information extracted from included studies
| Author | Publication year | Country/Region | Participants | Sample (n); (Number of experimental/control) | Overall age (Mean ± SD) (years) | BMI (Mean ± SD) (kg/m2) | Male (%); (experimental/control) | Intervention | Comparison | Intervention duration (wks) |
|---|---|---|---|---|---|---|---|---|---|---|
| S. G. Aldana | 2007 | America/America | Patients with coronary artery disease | 93(46/47) | 62.0±9.1 | 31.0±6.2 | 57.0(47.8/64.6) | Low-fat vegan | Omnivorous | 18 weeks |
| D. Djekic | 2020 | Sweden/Europe | Patients with ischemic heart disease | 31(16/15) | 67.0±9.9 | 28.0±2.9 | 93.5(93.8/93.3) | Lacto-vegetarian | Omnivorous | 4 weeks |
| D. Ornish | 1990 | America/America | Patients with coronary artery disease | 41(22/19) | 55.4±8.2 | 27.5±4.7 | 87.8(95.5/78.9) | Low-fat vegan | Omnivorous | 36 weeks |
| D. Ornish | 1998 | America/America | Patients with coronary heart disease | 35(20/15) | 59.3±6.9 | 27.1±3.8 | 91.4(100.0/80.0) | Low-fat vegan | Omnivorous | 48 weeks |
| B. Shah | 2018 | America/America | Patients with coronary artery disease | 100(50/50) | 61.3±7.4 | - | 85.0(86.0/84.0) | Low-fat vegan | Omnivorous | 8 weeks |
| D. J. Toobert | 2000 | America/America | Patients with coronary heart disease | 25(14/11) | 63.6±10.4 | 32.0±4.8 | 100.0(100.0/100.0) | Lacto-vegetarian | Omnivorous | 48 weeks |
Risk of bias assessment
The risk of bias, assessed using the RoB 2.0 tool, indicated five high-quality studies and one with some concerns (Fig. 2). The primary concerns were related to lack of allocation concealment, lack of blinding of participants or outcome assessors, or potential selective reporting.
Fig. 2.
Results of risk of bias assessment of included studies
Effect of vegetarian or vegan diets on cardiovascular metabolic risk factors in CVD patients
Systolic blood pressure
As shown in Fig. 3A, five studies involving 225 CVD patients reported SBP as the main outcome. The meta-analysis results indicated that, compared with an omnivorous diet, vegetarian or vegan diets did not result in a statistically significant reduction in SBP among CVD patients [MD = -0.59 mmHg (95%CI [-3.06, 1.88], P = 0.640), I² = 0%].
Fig. 3.
Forest plots. A Systolic blood pressure (SBP). B Diastolic blood pressure (DBP). C Total cholesterol (TC). D High-density lipoprotein cholesterol (HDL-C). E Low-density lipoprotein cholesterol (LDL-C). F Triglycerides (TG)
Diastolic blood pressure
As illustrated in Fig. 3B, five studies comprising a total of 225 patients with CVD assessed diastolic blood pressure as the primary outcome. The pooled analysis demonstrated that vegetarian or vegan diets were not associated with a statistically significant reduction in diastolic blood pressure compared with an omnivorous diet [MD = 0.31 mmHg (95%CI [-1.92, 2.54], P = 0.790), I² = 0%].
Total cholesterol
Figure 3C showed that six studies, including 325 patients with CVD, evaluated TC as the primary outcome. The meta-analysis results indicated that, compared with an omnivorous diet, vegetarian or vegan diets significantly reduced TC levels in patients with CVD [MD = -0.63 mmol/L (95%CI [-1.20, -0.05], P = 0.030), I² = 93%]. Further subgroup analyses of TC were conducted to better estimate the results (Table 2). Subgroup analysis showed that a low-fat vegan diet reduced TC levels among patients with CVD [MD = -0.77 mmol/L (95%CI [-1.54, -0.00], P = 0.049)], whereas no statistically significant improvement was observed with a lacto-vegetarian diet. Vegetarian or vegan diets with a duration of less than 24 weeks showed greater effectiveness in reducing TC levels among patients with CVD [MD = -1.23 mmol/L (95%CI [-1.77, -0.70], P = 0.045)]. In addition, subgroup analyses indicated that vegetarian or vegan diets were more effective in lowering TC levels in CVD patients aged ≤ 60 years [MD = -1.49 mmol/L (95%CI [-1.72, -1.26], P = 0.000)] and those with a BMI < 30 [MD = -0.41 mmol/L (95%CI [-0.70, -0.11], P = 0.007)].
Table 2.
Results of subgroup analysis of included studies in the meta-analysis
| Groups | n | Total cholesterol | n | HDL-C | n | LDL-C | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| MD(95%CI) | I² (%) | P-value | MD(95%CI) | I²(%) | P-value | MD(95%CI) | I²(%) | P-value | ||||
| Vegetarian diet type | ||||||||||||
| Low-fat vegan | 4 | -0.77(-1.54,-0.00) | 94.6 | 0.049 | 4 | -0.06(-0.11,-0.01) | 0.0 | 0.012 | 4 | -0.76(-1.50,-0.01) | 95.6 | 0.047 |
| Lacto-vegetarian | 2 | -0.27(-0.84,0.31) | 50.4 | 0.358 | 2 | 0.04(-0.12,0.19) | 0.0 | 0.649 | 2 | -0.15(-0.39,0.08) | 35.9 | 0.203 |
| Intervention duration (weeks) | ||||||||||||
| ≤ 24 | 3 | -1.23(-1.77,-0.70) | 0.0 | 0.045 | 3 | -0.05(-0.11,0.02) | 0.0 | 0.155 | 3 | -0.15(-0.30,0.00) | 0.0 | 0.054 |
| > 24 | 3 | -0.63(-1.22,-0.05) | 56.3 | 0.000 | 3 | -0.06(-0.14,0.02) | 5.9 | 0.169 | 3 | -0.97(-1.81,-0.14) | 93.9 | 0.023 |
| Overall age (years) | ||||||||||||
| ≤ 60 | 2 | -1.49(-1.72,-1.26) | 4.1 | 0.000 | 2 | -0.07(-0.14,-0.00) | 0.0 | 0.039 | 2 | -1.42(-1.61,-1.22) | 0.0 | 0.000 |
| > 60 | 4 | -0.33(-0.63,-0.04) | 8.6 | 0.026 | 4 | -0.04(-0.10,0.02) | 0.0 | 0.230 | 4 | -0.17(-0.31,-0.04) | 0.0 | 0.012 |
| BMI (kg/m2) | ||||||||||||
| < 30 | 3 | -0.41(-0.70,-0.11) | 0.0 | 0.007 | 3 | -0.06(-0.13,0.00) | 0.0 | 0.054 | 3 | -0.89(-1.95,0.18) | 97.6 | 0.103 |
| ≥ 30 | 2 | -0.90(-2.00,0.21) | 96.0 | 0.112 | 2 | -0.03(-0.18,0.12) | 37.6 | 0.720 | 2 | -0.28(-0.51,-0.04) | 0.0 | 0.022 |
| Not-reported | 1 | -0.13(-0.44,0.18) | - | 0.414 | 1 | 0.00(-0.13,0.13) | - | 1.000 | 1 | -0.21(-0.46,0.04) | - | 0.102 |
HDL-C high-density lipoprotein cholesterol, LDL-C low-density lipoprotein cholesterol, BMI body mass index, MD mean difference, CI confidence interval
High-density lipoprotein cholesterol
As presented in Fig. 3D, six studies comprising 325 patients with CVD assessed HDL-C as the primary outcome. The pooled analysis demonstrated that vegetarian or vegan diets were associated with a statistically significant reduction in HDL-C levels compared with an omnivorous diet [MD = -0.05 mmol/L (95%CI [-0.10, -0.01], P = 0.023), I² = 0%]. Further subgroup analyses showed that low-fat vegan diets were associated with reduced HDL-C levels among patients with CVD [MD = -0.06 mmol/L (95%CI [-0.11, -0.01], P = 0.012)], whereas no statistically significant reduction was observed with lacto-vegetarian diets. Moreover, vegetarian or vegan diets led to a greater reduction in HDL-C levels among CVD patients aged ≤ 60 years [MD = -0.07 mmol/L (95%CI [-0.14, -0.00], P = 0.039)].
Low-density lipoprotein cholesterol
Figure 3E summarizes data from six studies involving 325 patients with CVD that assessed LDL-C as the primary outcome. The pooled analysis revealed that vegetarian or vegan diets were associated with a significant reduction in LDL levels compared with an omnivorous diet [MD = -0.56 mmol/L (95%CI [-1.09, -0.02], P = 0.041), I² = 95%]. Subgroup analyses further demonstrated that a low-fat vegan diet significantly decreased LDL-C levels in patients with CVD [MD = -0.76 mmol/L (95%CI [-1.50, -0.01], P = 0.047)], whereas no significant effect was observed with a lacto-vegetarian diet. Greater reductions in LDL-C levels were observed with vegetarian or vegan interventions lasting more than 24 weeks [MD = -0.97 mmol/L (95%CI [-1.81, -0.14], P = 0.023)]. In addition, subgroup analyses indicated that vegetarian or vegan diets were more effective in lowering LDL-C levels in CVD patients aged ≤ 60 years [MD = -1.42 mmol/L (95%CI [-1.61, -1.22], P = 0.000)] and those with a BMI ≥ 30 [MD = -0.28 mmol/L (95%CI [-0.51, -0.04], P = 0.022)].
Triglycerides
As shown in Fig. 3E, six studies involving 325 CVD patients reported TG as the main outcome. The pooled analysis showed that vegetarian or vegan diets were not associated with a statistically significant decrease in TG levels compared with omnivorous diets [MD = 0.34 mmHg (95%CI [-0.06, 0.75], P = 0.100), I² = 84%].
Sensitivity analysis
Leave-one-out sensitivity analysis indicated that no single study significantly influenced the overall results for SBP, DBP, TC, HDL-C, LDL-C, and TG, suggesting robustness of the findings (Supplementary Fig. 1). A vegetarian or vegan diet significantly reduced cholesterol-related outcomes in patients with CVD.
Publication bias and heterogeneity
Publication bias was analyzed by the funnel plot and Egger’s test. The funnel plots of studies reporting SBP, DBP, TC, HDL-C, LDL-C, and TG were visually symmetrical, and the P-values of Egger’s test were 0.573, 0.394, 0.510, 0.110, 0.829, and 0.326, respectively, suggesting no publication bias (Supplementary Fig. 2). The results of the meta-analysis revealed significant heterogeneity across outcome measures (TC: I² = 93%; HDL-C: I² = 0%; LDL-C: I² = 95%). To investigate potential sources of heterogeneity, subgroup analyses were conducted. Results suggested that vegetarian diet type, intervention duration, overall age, and BMI may be sources of heterogeneity.
Discussion
The results of the systematic review and meta-analysis indicated that vegetarian or vegan diets significantly reduced TC, HDL-C, and LDL-C levels in patients with CVD compared to an omnivorous diet. Notably, a low-fat vegan diet demonstrated superior effectiveness in reducing lipid levels among patients with CVD compared to a lacto-vegetarian diet. Additionally, vegetarian dietary interventions with a duration of ≤ 24 weeks were more effective in reducing TC levels, whereas interventions lasting > 24 weeks showed greater effectiveness in lowering LDL-C levels. Furthermore, greater lipid-lowering effects of vegetarian or vegan diets were observed in patients with CVD aged ≤ 60 years, while no clear effect was evident in those older than 60 years. Differences according to BMI were also observed, with vegetarian diets significantly lowering TC levels in CVD patients with a BMI < 30 kg/m2 and LDL levels in those with a BMI ≥ 30 kg/m2.
The reductions in lipid levels observed among patients with CVD following vegetarian or vegan dietary interventions may be attributed to several factors: Firstly, plant-based diets are characteristically low in saturated fats and dietary cholesterol, which are major determinants of circulating cholesterol levels [21]. Reduced intake of saturated fats decreases hepatic very-low-density lipoprotein (VLDL) production and LDL-C formation, leading to lower TC and LDL-C concentrations in the bloodstream [22]. In contrast to omnivorous diets, vegetarian and vegan diets emphasize foods low in animal fats, thereby attenuating endogenous cholesterol synthesis and transport pathways linked to atherogenic lipoproteins [23]. This compositional effect has been supported by meta-analytic evidence showing consistent reductions in TC and LDL-C with plant-based dietary patterns compared with omnivorous diets [24]. Secondly, these diets tend to be rich in dietary fiber and plant sterols, both of which are known to influence lipid metabolism [25, 26]. Soluble fibers (such as β-glucans from oats and pectins from fruits) bind bile acids in the intestine, enhancing their excretion and promoting the hepatic conversion of cholesterol into bile acids, thereby lowering circulating LDL-C and TC levels [27]. Plant sterols compete with dietary cholesterol for intestinal absorption, further reducing cholesterol uptake and lowering plasma LDL-C [28]. The role of these components in lipid lowering is well documented in nutrition research and forms a key mechanistic basis for the observed effects of plant-based diets on blood lipids. Finally, although HDL-C has traditionally been regarded as “protective” cholesterol, its cardioprotective role remains incompletely understood. Previous studies have shown that pharmacological elevation of HDL-C does not necessarily reduce cardiovascular risk, and extremely high HDL-C levels have even been associated with increased mortality risk [29, 30]. Therefore, reductions in HDL-C observed with plant-based dietary interventions should not necessarily be interpreted as adverse. Instead, the overall cardiometabolic benefits of vegetarian and vegan diets are more likely driven by reductions in atherogenic lipoproteins such as LDL-C and TC.
In addition, the subgroup analysis showed that the low-fat vegan diet demonstrated superior effectiveness in reducing lipid levels among patients with CVD compared to the lacto-vegetarian diet. One fundamental nutritional difference is the absence of dietary cholesterol and minimal saturated fat intake in low-fat vegan diets, as these diets exclude all animal products and typically emphasize whole plant foods with low fat content [5]. In contrast, lacto-vegetarian diets include dairy products, which contribute saturated fat and dietary cholesterol that can attenuate the lipid-lowering effects of plant-based eating patterns [31]. In addition to differences in saturated fat and dietary cholesterol intake, emerging evidence suggests that gut microbiota modulation may contribute to the superior lipid-lowering effects of low-fat vegan diets. High-fiber, plant-rich dietary patterns can increase the abundance of cholesterol-degrading bacterial taxa, such as Oscillibacter, thereby facilitating cholesterol metabolism and excretion [32]. Furthermore, fermentation of dietary fibers by gut microbiota produces short-chain fatty acids (SCFAs), including butyrate and propionate, which may regulate hepatic cholesterol synthesis and bile acid metabolism [33]. Another potential mechanism involves the direct lipid-lowering effects of plant protein. Independent of saturated fat reduction, higher intake of plant-derived proteins has been associated with decreased LDL-C concentrations, possibly through modulation of hepatic LDL receptor activity and cholesterol homeostasis [34]. Compared with lacto-vegetarian diets, low-fat vegan diets generally contain greater amounts of legumes, soy products, and other plant protein sources, which may further enhance improvements in lipid profiles. In addition, subgroup analyses revealed that vegetarian or vegan diets exerted more pronounced lipid-lowering effects in patients with cardiovascular disease aged ≤ 60 years, whereas no significant effect was observed in those older than 60 years. The age-related differences in lipid-lowering responses may reflect variations in metabolic flexibility and dietary responsiveness across the lifespan. Younger patients (≤ 60 years) generally exhibit greater metabolic adaptability, allowing dietary modifications such as vegetarian or vegan diets to more effectively reduce lipid levels [35]. In contrast, older patients (> 60 years) often present with age-related dysregulation of lipid metabolism, accumulated cardiometabolic comorbidities, and long-term pharmacological treatment, which may attenuate the lipid-lowering effects of dietary interventions [36]. Additionally, reduced dietary adherence and blunted physiological responses to nutritional changes in older adults may further contribute to the diminished effects observed in this age group [37].
Subgroup analyses further indicated that the lipid-lowering effects of vegetarian dietary interventions varied according to both intervention duration and BMI. Shorter interventions (≤ 24 weeks) were associated with greater reductions in total cholesterol (TC), whereas longer durations (> 24 weeks) favored LDL-C reduction. Moreover, TC lowering predominated in patients with a BMI < 30 kg/m², while greater LDL-C reductions were observed in those with a BMI ≥ 30 kg/m². The observed variation in lipid-lowering effects according to intervention duration and BMI likely reflects differences in underlying lipid metabolism, dietary responsiveness, and temporal adaptations to vegetarian dietary patterns. With respect to intervention duration, shorter-term vegetarian dietary interventions (≤ 24 weeks) appeared to preferentially reduce total cholesterol (TC). This effect may be primarily driven by rapid changes in dietary cholesterol intake and saturated fat consumption following the initiation of a vegetarian diet. Early reductions in dietary cholesterol and saturated fat can promptly decrease hepatic cholesterol pools and circulating TC levels through reduced intestinal cholesterol absorption and downregulation of hepatic cholesterol synthesis [38]. These short-term effects are often most pronounced soon after dietary modification, before longer-term metabolic adaptations occur. In contrast, longer intervention durations (> 24 weeks) were more strongly associated with reductions in LDL-C. Sustained adherence to vegetarian diets may induce gradual improvements in lipoprotein metabolism, including enhanced LDL receptor activity, increased bile acid excretion, and long-term alterations in hepatic lipid handling [39]. Over time, consistent intake of dietary fiber, plant sterols, and polyphenols may further suppress endogenous cholesterol synthesis and promote clearance of LDL particles from circulation, thereby exerting a more pronounced effect on LDL-C levels than on TC alone. Differences according to BMI further suggest heterogeneity in metabolic responsiveness. In patients with a BMI < 30 kg/m², TC reductions predominated, possibly reflecting relatively preserved metabolic flexibility and a more immediate response to reductions in dietary cholesterol intake. In these individuals, baseline lipid abnormalities may be less driven by insulin resistance and adiposity-related dyslipidemia, allowing TC to respond rapidly to dietary modification. Conversely, in patients with a BMI ≥ 30 kg/m², greater reductions in LDL-C were observed. Obesity is commonly associated with insulin resistance, increased hepatic VLDL production, and impaired LDL clearance [40]. Long-term vegetarian dietary interventions may improve insulin sensitivity, reduce hepatic lipid accumulation, and enhance LDL receptor–mediated clearance, leading to more pronounced reductions in LDL-C [41, 42]. In this context, LDL-C may represent a more sensitive marker of metabolic improvement than TC in individuals with higher BMI. Taken together, these findings suggested that both the duration of vegetarian dietary interventions and baseline adiposity modify their lipid-lowering effects. Short-term interventions may primarily influence overall cholesterol burden, whereas longer-term adherence and higher BMI status appear to favor improvements in atherogenic lipoproteins, particularly LDL-C. This heterogeneity underscores the importance of considering intervention duration and patient characteristics when evaluating and individualizing dietary strategies for lipid management in patients with cardiovascular disease.
Although the results of this study are robust, there were several potential limitations that should be noted. Firstly, most included studies had relatively short follow-up durations, limiting the evaluation of long-term lipid changes and the sustainability of dietary effects. Long-term intervention studies with extended follow-up are warranted to assess the durability of lipid-lowering effects and their implications for cardiovascular outcomes. Secondly, potential confounders, including lipid-lowering medications, physical activity, and other lifestyle factors, were not uniformly controlled across studies. Future trials should employ rigorous adjustment strategies or stratified analyses to account for concomitant therapies and lifestyle behaviors, thereby isolating the independent effects of vegetarian dietary interventions. Thirdly, this meta-analysis only included English-language studies, which may not capture the full scope of global research on this topic. Despite these limitations, the results of this study are still valuable, supported by a large sample size, combined factor analysis, and reliable analytical methods.
Conclusion
This systematic review and meta-analysis demonstrate that vegetarian or vegan dietary interventions are associated with significant improvements in lipid profiles among patients with CVD, particularly reductions in TC and LDL-C. The lipid-lowering effects varied according to dietary subtype, intervention duration, age, and BMI, with low-fat vegan diets showing greater efficacy than lacto-vegetarian diets, shorter interventions preferentially reducing total cholesterol, and longer interventions favoring reductions in LDL-C. In addition, younger patients and those with lower or higher BMI exhibited differential lipid responses, highlighting the heterogeneity of dietary effects across patient subgroups. Collectively, these findings suggest that vegetarian or vegan dietary patterns may serve as effective adjunct strategies for managing cardiovascular risk factors in patients with CVD. Furthermore, personalized dietary recommendations should be developed for different patient groups.
Supplementary Information
Acknowledgements
None.
Clinical trial number
Not applicable.
Abbreviations
- CVD
Cardiovascular disease
- RCTs
Randomized controlled trials
- SBP
Systolic blood pressure
- DBP
Diastolic blood pressure
- TC
Total cholesterol
- HDL-C
High-density lipoprotein cholesterol
- LDL-C
Low-density lipoprotein cholesterol
- TG
Triglycerides
- MDs
Mean differences
- CIs
Confidence intervals
- SDs
Standard deviations
- BMI
Body mass index
- VLDL
Very-low-density lipoprotein
- SCFAs
Short-chain fatty acids
Authors’ contributions
Saikun Wang contributed to Data Curation, Formal Analysis, and Writing – original draft; Hao Liu and Kiu Kun contributed to Formal Analysis and Investigation; Chao Sun contributed to Resources and Validation; Chunhua He contributed to Data Curation; Wenyu Cai contributed to Software; Yihao Zhang contributed to Conceptualization; Zhenhua Wang, Yanbin Liu, and Yang Zhang contributed to Supervision and Writing – review & editing.
Funding
This study was supported by the Shandong Provincial Medical and Health Science and Technology Project (Grant No. 202416010384), Project of Jinan Science and Technology Plan (Grant No. 202430052), Research and Innovation Team Project of Shandong University of Traditional Chinese Medicine Affiliated Hospital (Grant No. 2024-72), and Focus on Research and Development Plan in Shandong Province (Grant No. 2025CXGC010606).
Data availability
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.
Declarations
Ethics approval and consent to participate
Not applicable.
Consent for publication
All authors have read and agreed to the published version of the manuscript.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Saikun Wang, Hao Liu and Kun Liu contributed equally to this work.
Contributor Information
Zhenhua Wang, Email: 444194328@qq.com.
Yanbin Liu, Email: tiwei786@163.com.
Yang Zhang, Email: 2571301744@qq.com.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.