The Benefits of Plant-Based Nutrition: Treatment and Prevention of Cardiovascular Disease

Populations consuming diets of whole plant foods have better cardiovascular risk profiles and lower rates of cardiac events and mortality. Lifestyle medicine practitioners should encourage patients to adopt a whole food, predominantly plant-based diet.

Abstract

The burden of cardiovascular disease (CVD) is increasing globally and continues to be the leading cause of death worldwide,1 responsible for roughly one in four deaths in the U.S. alone.2 Modifiable lifestyle risk factors are associated with most acute myocardial infarctions,3 including many dietary risk factors including red and processed meat, saturated fat, refined carbohydrates, excess sodium, and inadequate fiber. Populations consuming diets centered on whole plant foods have better cardiovascular risk profiles and lower rates of cardiac events and mortality.4 Lifestyle medicine practitioners can best support cardiac health in patients by encouraging adoption and maintenance of a whole food, predominantly plant-based diet.

Cardiovascular Disease in Context

Cardiovascular disease (CVD) is a group of heart and blood vessel disorders that include coronary heart disease, cerebrovascular disease, rheumatic heart disease, and other circulatory conditions, including heart failure, arrhythmias, and stroke.^{5, 6} The most common cause of CVD is Ischemic Heart Disease (IHD), often developed by atherosclerotic narrowing of the coronary arteries. Over the past fifty years, there has been a significant drop in CVD-related mortality.⁷ However, despite substantial advances over the past decade in all areas of cardiovascular medicine, CVD remains the leading cause of death across the world.^2–6

As outlined in the most recent Global Burden of Cardiovascular Disease data, the risk factors for CVD and the associated burden of heart disease continue to rise in low- to middle-income nations.⁶ In addition to conventional risk factors (hypertension, smoking, diabetes, obesity, hyperlipidemia, chronic kidney disease), psychological factors⁸ and social determinants of health^{6, 9} play a significant role.

Food insecurity as a social determinant of health is an important factor contributing to CVD burden.¹⁰ At a population level, 90% of the attributable cardiovascular risk is modifiable through lifestyle changes.⁸ Diet-induced risk is an important contributor to CVD risk.^{11, 12} Atherosclerosis has been shown to be associated with dietary intake of red and processed meat,¹³ saturated fat,^{14, 15} and refined carbohydrates.^{16, 17} Globally, the diet-induced risk is primarily due to increased consumption of sodium and low intake of whole grains and fruits,¹⁸ as well as overconsumption of ultrapocessed foods.^19–21 The cost of healthcare and lost productivity due to CVD in the U.S. is in excess of $300 billion per year,^{22, 23} and suboptimal diet has been shown to be contributing to over 18% of this spending.²⁴

Pathophysiology of CVD

CVD begins with progressive endothelial injury,²⁵ inflammatory oxidative stress, diminution of nitric oxide production, foam cell formation, and development of plaques that may rupture to cause a myocardial infarction (MI) or stroke.²⁶ Heart attacks and strokes are usually acute events caused by blockages that prevent blood from flowing to the heart or brain. The most common reason for this is a buildup of deposits made of fat, cholesterol, calcium, and other substances on the inner wall of the blood vessels that supply the heart or brain.¹ Diet has long been implicated in the pathophysiology of CVD with excess amounts of added oils, dairy, meat, fowl, fish, and sugary foods. Insufficient micronutrient density and disproportioned macronutrients are also studied variables.^{18, 27} These foods can injure or impair endothelial function after each ingestion, making food choices a major, if not the major, cause of coronary artery disease.^{25, 28–31} Most CVD can be prevented by addressing behavioral risk factors such as unhealthy diet and obesity, physical inactivity, tobacco use, and harmful alcohol use.³²

Inflammation

Inflammation, as it relates to atherosclerosis and CVD, is a complex and highly regulated interaction between many cellular and molecular mechanisms.³³ There are multiple sources of inflammation, some modifiable and others non-modifiable. Smoking, dyslipidemia, diabetes, obesity, perivascular fat deposition, reactive oxygen species, diet, and gut microbiome have been shown to contribute to arterial inflammation, and increased risk of CVD.³⁴ Diet plays a significant role in inflammation and cardiovascular risk.

In a recent analysis of the Nurses’ Health Study and the Health Professionals Follow-up Study, it was shown that diets with high inflammatory potential (red meat, processed meat, organ meat, refined carbohydrates, sugar-sweetened beverages) are associated with increased risk of CVD.^{35, 36} Diets high in saturated fat have been shown to increase levels of C-Reactive Protein (CRP), Tumor Necrosis Factor Alpha (TNF alpha), Interleukin 6 (IL-6), Vascular Cell Adhesion Protein 1(VCAM-1) and Intercellular Adhesion Molecule 1 (ICAM-1).^{37, 38} The consumption of hydrogenated trans fats has been shown to increase the levels of multiple markers of inflammation and the overall risk of CVD,^{39, 40} as have diets high in refined carbohydrates⁴¹ and sugars.⁴² Diets rich in polyunsaturated fats and fiber have been shown to lower inflammatory markers.⁴³

Inflammation and hypertension interact as CVD begins to make structural changes in the arteries. Inflammation is marked by circulating inflammatory molecules, including CRP and IL-6,⁴⁴ which are predictors of future CVD.⁴⁵ One study of men and women in their 40’s with high BMIs (n=29) showed a significant and drastic reduction in systemic inflammation, as indicated by decreased CRP. Reducing systemic inflammation appears essential, considering that increased inflammation and oxidative stress emerge as underlying pathophysiologic mechanisms of aging and age-related diseases.^46–48 An inability to scavenge and quench reactive oxygen and nitrogen species that can harm endothelial cells is linked to oxidative stress and CVD.⁴⁹

According to some research, added oils are not causally implicated in CVD, though it does appear that the type of fat is more important to oxidative stress and inflammation, notably saturated fatty acids, which come from animal foods. On the other hand, vegetable oil used in place of animal fat has consistently shown to lower CVD.^{50, 51}

Trimethylamine N-oxide (TMAO) 

Dietary nutrient intake and its metabolism by the gut microbiome have recently been associated with CVD risk. In particular, TMAO, a metabolite of the gut microbiota, is a predictor of incident CVD events.⁵² L-carnitine, an abundant nutrient in red meat, accelerates atherosclerosis in mice via gut microbiota-dependent formation of trimethylamine (TMA) and TMAO. This production happens via a multistep pathway involving an atherogenic intermediate, γ-butyrobetaine (γBB). The contribution of γBB in gut microbiota-dependent L-carnitine metabolism in humans is still unknown. However, studies with oral d3-L-carnitine or d9-γBB before versus after antibiotic exposure reveal that gut microbiota contributes to the initial two steps in a metaorganismal L-carnitine→γBB→TMA→TMAO pathway in subjects.^{52, 53} Observational research, including Mendelian randomization studies, find reverse causation between TMAO levels and chronic disease like CVD, in that the disease is causally associated with TMAO levels.³⁸

The gut flora processes dietary carnitine into TMA, which the liver converts into TMAO.⁵⁴ Elevated levels of TMAO have been shown to be associated with increased risk of coronary artery disease, myocardial infarction, and peripheral arterial disease, independent of conventional risk factors.⁵⁵ Elevated levels of TMAO have also been shown to predict risk of major adverse cardiac events such as myocardial infarction, stroke, and death.^{54, 56} Fasting levels of TMAO have been shown to predict atherosclerotic burden and extent of coronary artery disease.⁵⁷ Similar prognostic utility of TMAO has been demonstrated in individuals with diabetes,⁵⁸ peripheral arterial disease,⁵⁹ and congestive heart failure.⁶⁰ These findings are independent of traditional cardiovascular risk factors and have been validated in two systematic reviews and meta-analyses.^61–63 Based on these observations, TMAO levels of greater than 6 μM are predictive of high risk and adverse cardiovascular events.⁶⁴ While TMAO levels predict risk, the mechanisms and causal link are now well established. It appears that elevated TMAO levels could be markers of reverse causation.⁶⁵

Effects of Plant-Based Diets on CVD and CVD Risk Factors

There are a variety of mechanisms by which plant-based nutrition can lead to decreased blood pressure, including improved vasodilation,⁴⁵ anti-inflammatory effects,^{45, 66, 67} greater antioxidant content,^68–70 improved insulin sensitivity,^{68, 71–74} decreased blood viscosity,^{75, 76} altered baroreceptors,⁶⁸ modifications in both the renin-angiotensin (cardiac blood outcome),^{71, 77, 78} and sympathetic nervous systems,^78–80 as well as modification of the gut microbiota.⁷⁸

A whole food, plant-based (WFPB) diet can restore the ability of endothelial cells to produce nitric oxide (NO).⁸¹ NO maintains vascular homeostasis, including modulation of vascular dilator tone, regulation of local cell growth, and protection of the vessel from injurious consequences of platelets and cells circulating in the blood, playing a crucial role in normal endothelial function.⁸¹

Protective benefits of the plant-based dietary pattern on cardiovascular function include lower risk of hypertension, obesity, inflammation, and insulin resistance.^{18, 82–84} Studies demonstrate that dietary cholesterol, saturated fat, and animal foods increase risk for CVD, while WFPB diets are associated with a more favorable cardiovascular disease biomarker profile and better vascular structural and functional parameters.^{18, 82–84} Dietary patterns that minimize or avoid dairy, meat, other animal products, and oils reduce modifiable risk factors of CVD.^{27, 82, 85–109} WFPB diets not only contain protective components that decrease risk, such as high fiber and antioxidants, but are also low or devoid of food components that increase risk, including saturated fat and added sugar, both associated with risk of CVD.¹¹⁰

Plant-Based Benefits for Cardiovascular Risk and Risk Factors

Accumulating evidence indicates the merits of plant-based diets to control and manage CVD due to the beneficial changes in cardiometabolic risk factors such as lower total serum cholesterol and glucose, BMI, inflammation, and blood pressure.¹¹⁰ Vegetarians have been found to have lower blood pressure and lower cardiovascular mortality.¹¹¹ These positive effects may be due to lower intakes of dietary cholesterol and saturated fat from red and processed meat, and conversely higher intakes of fiber, plant protein, and phytonutrients from whole grains, fruits, nuts, and vegetables,¹¹⁰ which can protect against risk factors including type 2 diabetes, as well as high sensitivity to CRP and the inflammatory IL-6 molecule.¹¹² It appears that a WFPB diet reduces inflammation, possibly due to eliminating these risk factors.^{66, 67, 113}

Population studies show that increased intake of plant foods reduces risk for CVD, including the Adventist Health Study-2, which found that ‘meat’ proteins are associated with increased risk, whereas nut and seed proteins are associated with lower risk.¹¹⁴ A systematic review and meta-analysis found that vegetarian-based dietary patterns have been associated with favorable biomarkers of low-grade inflammation as indicated by immune biomarkers (CRP, TNF alpha, fibrinogen, natural killer cells, leukocytes, lymphocytes, thrombocytes, interleukins, and immunoglobulins).¹¹⁵ These markers work synergistically as a protective response to environmental, mechanical, or pathological challenges and are predictors of CVD risk, all-cause mortality, diabetes, and some cancers. Evidence suggests that plant-based diets may attenuate markers or chronic inflammation.¹¹⁵

The Nurses’ Health Study data provided compelling evidence that diet and lifestyle strongly influence CVD incidence and point to high levels of heme iron and saturated fatty acids in red meats. A significant inverse association was observed in this study between those adhering to a plant-predominant Mediterranean dietary pattern and CVD risk.³² In the MESA study (Multi-Ethnic Study of Atherosclerosis), apolipoprotein C-III found on 6%-7% of HDL particles are adversely associated with CVD. Apolipoprotein C-III is a proinflammatory atherogenic lipoprotein that appears to impair the removal of triglycerides from the blood.¹¹⁶

Long-term practices associated with the pillars of lifestyle medicine, particularly the consumption of a whole food, plant-predominant diet, and/or regular endurance exercise, are associated with lower cardiometabolic risk.¹¹⁷ Additionally, plant-based diets provide beneficial effects on blood pressure and are inversely associated with sodium intake, as demonstrated in the Dietary Approaches to Stop Hypertension (DASH) study, the Coronary Artery Risk Development in Young Adults (CARDIA) study, and three prospective cohorts of the Nurses’ Health Study I and II.¹¹⁸ A 2021 meta-analysis of 13 studies (N= 1,427,989) found that unprocessed meat consumption was associated with a 9% higher incidence (95% CI 1.06, 1.12; n=12 studies) of IHD, and processed meat was associated with an 18% higher risk (95% CI, 1.12 to 1.25; n=10 studies).¹¹⁹ In this same analysis, poultry consumption was unrelated to IHD risk.¹¹⁹ This underscores the benefit of plant-based diets that avoid both red and processed meat.

Those with obesity are more likely to develop CVD.^120–122 For those at higher genetic risk for obesity, a plant-based dietary pattern has been shown to significantly attenuate the risks of CVD. A large prospective study (N= 121,799) published in 2021¹²³ found that those with this genetic predisposition may be more responsive to the benefits of a healthy plant-based eating pattern and that healthy plant-based dietary patterns can attenuate their genetic risk for obesity and CVD comorbidities.¹²³ Researchers saw a 26% decreased risk for myocardial infarction (HR 0.74 [0.60, 0.91]).¹²³ This confirms an earlier study showing a 25% reduced risk of ischemic heart disease among participants using a vegetarian diet (RR 0.75, 95% CI 0.68 to 0.82).¹²⁴ The modified risk factors included controlling blood pressure and HDL cholesterol levels.¹²³

Plant-Based Interventions

Intervention studies find that plant-based diets are effective in improving all cardiometabolic markers, such as in an intensive, 10-day health promotion program (n=16) that significantly reduced body weight, body mass index, triglyceride, total cholesterol, low-density lipoprotein cholesterol, blood glucose, and the homeostasis model assessment of insulin resistance.¹²⁵ The Lyon Diet Heart Study, a randomized, single-blind trial, demonstrated that a Mediterranean-type diet rich in omega-three fats, fruits, and vegetables may reduce the rate of recurrence after an initial myocardial infarction and that the protective effects of the diet are maintained up to four years after the first infarction.¹²⁶ A multicenter randomized controlled GEICO study corroborates these results, demonstrating that a low-fat, plant-based diet yielded significant improvements in health metrics, including plasma lipids and weight.¹²⁷ These simple nutrition interventions in widely divergent regions demonstrate that dietary changes towards a plant-predominant pattern yield cardio-protective results.^{126, 127}

Dietary intakes can also modify TMAO. An increase in d3-TMAO generation was observed in omnivores over vegans/vegetarians (>20-fold; P = 0.001) following oral d3-L-carnitine ingestion, whereas fasting endogenous plasma L-carnitine and γBB levels were similar in the vegans/vegetarians (n = 32) versus omnivores (n = 40).⁵³ In humans, dietary L-carnitine is converted into the atherosclerosis- and thrombosis-promoting metabolite TMAO via two sequential gut microbiota-dependent transformations: (a) initial rapid generation of the atherogenic intermediate γBB, followed by (b) transformation into TMA via low-abundance microbiota in omnivores and, to a markedly lower extent, in vegans/vegetarians. Gut microbiota γBB→TMA/TMAO transformation is induced by omnivorous dietary patterns and chronic L-carnitine exposure.⁵³

Plant-Based Benefits for Comorbidities with CVD

Hypertension

Hypertension is a leading risk factor for heart failure and stroke. Though first-line therapies for all stages of hypertension include weight loss and exercise, studies show that a plant-based diet is the more effective intervention. This has been demonstrated since the late 1930s with Dr. Walter Kempner’s rice diet, which demonstrated normalization of blood pressure with a high complex carbohydrate diet,¹²⁸ and the Dietary Approaches to Stop Hypertension (DASH) controlled feeding study, which reduced both systolic and diastolic blood pressure by 5.5 mmHg and 3.0 mmHg, respectively, in their intervention group.¹²⁹ The diet high in fruits and vegetables but otherwise similar to the control diet also lowered blood pressure but not to the same extent as the DASH diet. However, other studies have shown that the specific components of the DASH diet, fruits, vegetables, whole grains, and nuts, were each associated with decreased blood pressure.^{11, 27, 82, 83, 85, 130} A prospective cohort study of N=4,¹⁰⁹ nonsmokers (n=3423 non-vegetarians and n=686 vegetarians) demonstrated that vegetarian diets may protect against hypertension beyond lower abdominal obesity, inflammation, and insulin resistance.¹³¹

Studies show that the nutritional and lifestyle factors that determine the lipid profile in populations suggest that the known age-dependent rise of atherogenic plasma lipoproteins is partly preventable.¹³² Individuals diagnosed with congestive heart failure (CHF) have a 50% five-year mortality rate,¹³³ and approximately 650,000 new cases of CHF are diagnosed annually. Low-fat, plant-based diets have been shown to improve plasma lipid concentrations, reduce blood pressure, and lead to the regression of atherosclerotic lesions compared to progression of lesions on a usual care control group diet.¹⁰⁷ However, a scarcity of data exists with regard to plant-based diets in the treatment of CHF.¹³⁴ In one study where three patients consumed a plant-based diet for an average of ~79 days, follow-up cardiac magnetic resonance images revealed significant improvements in angina, shortness of breath and fatigue: 92% increase in ejection fraction [mean ± standard deviation for all data] (22.0 ± 6.9% vs 42.2 ± 18.4%), 21% reduction in left ventricular mass (214 ± 90 g vs 170 ± 102 g), 62% increase in stroke volume (55.8 ± 24.3 cc vs 90.3 ± 30.6 cc) and 17% increase in cardiac output (3.6 ± 1.2 L/min vs 4.2 ± 1.6 L/min).¹³⁴

Diabetes

Although the Framingham cohort study first established diabetes as a major risk factor for CVD,¹³⁵ the American Heart Association now considers this risk factor to be controllable. Adults with diabetes are more likely to die from heart disease than from diabetes itself.¹³⁶ Cardiologists should be prepared for this common comorbidity and be involved in the diabetes care of their patients. Though diabetes care was traditionally in the purview of primary care physicians and/or endocrinologists, the two diseases mandate a multidisciplinary approach¹³⁷ that lifestyle medicine is well-positioned to address.¹³⁸ Expertise in type 2 diabetes (T2D) care may fall under a cardiovascular specialist with or without endocrinology specialist care. Plant-based diets have demonstrated effectiveness in controlling blood sugar and insulin sensitivity, thus ameliorating T2D, as they help control excess body weight through dietary fiber intake and decreased saturated fat. Dietary fiber regulates and controls macronutrients, particularly glucose,and supports a healthy gut lining to avoid inflammation and toxins leaking into the blood. Further, animal protein and fat have been linked to insulin resistance and higher incidence of T2D.^139–141 More information on the benefits of plant-based diets for T2D can be found in the paper on T2D in this series.

Hyperlipidemia

Diets high in saturated fat have been shown to increase LDL-C,¹⁴² a known causal factor in atherosclerosis development, and CVD.¹⁴³ Apolipoprotein B, the main structural protein of LDL, is directly associated with CVD. Both apolipoprotein C-III and apolipoprotein B are lipoproteins that promote macrophage foam cell formation, which is the hallmark of the fatty streak phase of atherosclerosis. These deposits in the arterial wall initiate an inflammatory response.¹⁴⁴

Mechanisms include a decrease in fat intake, particularly LDL particles, to lessen oxidation, which controls nitric oxide damage to fragile endothelial cells.^145–148 Inversely, plant-based diets may reduce reactive oxygen species (ROS), which induces aortic stiffness potentially progressing to heart failure.^149–151

Obesity

Overweight and obesity is a leading risk factor and comorbidity of CVD.¹⁵² Though mortality from heart disease substantially declined in the first decade of the 21st century due to medical therapies, obesity may be responsible for the tremendous rise in chronic disease rates, including cancer and diabetes, and a deceleration of CVD mortality since 2011.¹⁵³ Weight loss, even a modest amount (5% of body weight), has demonstrated risk reduction of CVD and comorbidities.^{154, 155} The paradox is that though weight loss decreases risk factors for CVD, there may be a protective effect of obesity resulting in an inverse correlation between body mass index (BMI) and mortality in certain groups of people, including those mildly overweight (class I), those with kidney disease, and the elderly.^{156, 157} Though cardiorespiratory fitness may be a better gauge of CVD risk than BMI, weight loss among overweight individuals can reduce physiologic and hemodynamic risk factors for CVD.¹⁵⁷

Though traditional weight loss has relied on calorie restriction or surgical intervention, plant-based diets have the advantage of higher diet quality to improve overall health.¹⁵⁸ In control trials, vegan groups lose more weight than with more traditional therapeutic diets that reduce saturated fat and calories, indicating that the adoption of a low-fat vegan diet improves several aspects of macronutrient intake, provided that adequate attention is paid to micronutrient-rich foods shown to decrease the risk of heart disease.^{159, 160} More information on the benefits of plant-based diets for obesity can be found in the paper on obesity in this series.

Common Questions and Concerns

Will patients get enough protein, fat, and vitamin B12 to support cardiometabolic health?

A well-planned whole food, plant-based diet provides all nutrients needed for optimal health and healing for the general public and those with CVD,^{164, 165} with the potential exception of vitamins B12 and D.¹⁶⁵ For treatment of chronic disease, beneficial effects are dose-dependent, where patients experience benefits dependent on sufficiently dosed lifestyle changes.^{164, 166}

Is there a risk to the consumption of all meat, or just red and processed meat?

Red and processed meat have been linked to cardiovascular disease in multiple studies.^{167, 168} Some studies show a dose-dependent relationship between animal food consumption and cardiovascular disease and mortality.¹⁶⁹ Yet others show no associations between unprocessed meat and poultry intake and CVD or mortality.¹⁶⁷ A 2020 prospective cohort study found that processed meat, unprocessed red meat, or poultry were significantly associated with incident cardiovascular disease, though fish intake was not.¹⁷⁰ Many studies have suggested that CVD can be effectively treated and, in some cases, the progression halted by lowering saturated fat, cholesterol, and animal protein, and incorporating nutrients from a plant-based diet.^{117, 124, 125, 171–174} Plant-based diets are associated with lower risk and incidence of CVD, ^{117, 145, 164, 174} for instance, in the European Prospective Investigation into Cancer and Nutrition-Oxford study, vegans had the lowest prevalence of hypertension.¹⁷⁵

Will patients be willing to make this significant change to their diet?

Research indicates that better adherence to a plant-based diet is associated with lower risk for CVD and better treatment results.^{117, 164} As their most trusted authority, healthcare practitioners can successfully guide their patients to implement this behavior change. It may need to be a collaborative effort;¹⁷⁶ it can take a village. For instance, a group may consist of a team made up of the primary care physician, nutritionist, nurse/nurse practitioner, and wellness coach, along with support group meetings or group sessions.¹⁷⁷ Behavior change techniques have been shown to aid in compliance, such as discovering the behavior change determinants of the patient to access at what stage of change the patient is presently at to ensure their ability to make goals for themselves. Using motivational interviewing can be a useful tool for the practitioner to convey empathy through reflective listening and to recognize resistance.^{176, 178, 179} Inclusion of the patient’s family, support group, or confidant is helpful.^{180, 181}

Will patients adhere to a plant-based diet?

Caring, empathetic practitioners increase the likelihood of patient adherence to their recommendations.^{176, 179} Knowing the patient’s concerns, beliefs, cultural context, and attitudes are important to their adherence.¹⁷⁶ Research shows that adherence to any diet depends on the same measures, including the patient’s motivation.¹³² Further, practitioners who demonstrate healthy lifestyle habits themselves have the most success in helping their patients to adopt healthier habits.¹⁸² Incorporating counseling, motivational interviewing and collaboration can inspire behavior change.^{176, 183} The POUNDS LOST study demonstrated that weight loss was contingent on adherence and that fiber exerted the most considerable influence on adherence.^{184, 185} A safe and healthy plant-based dietary treatment that induces weight loss will lower CVD risk.¹⁸⁶ In a randomized crossover trial of adults (N=62) with high BMI (30 kg/m2 to 37 kg/m2), adherence was high to both diets.¹⁶³

Early Studies and Case Studies Highlighting a Path Toward Halting CVD Disease Progression

Esselstyn Patient Cohort

Dr. Caldwell Esselstyn, physician at the Cleveland Clinic, had demonstrated the arrest of coronary artery disease (CAD) in both a small study (N=19),⁸⁹ as well as a more recent case series following N=198 consecutive patients.⁹³ All participants were intensively counseled in plant-based nutrition and instructed to consume minimal to no amounts of nuts and seeds, avocado, and nut butters, and avoid all refined foods, added sugars, and animal foods. The results demonstrated that a strict low-fat (<10%) plant-based diet can lower serum cholesterol to <150 mg/dl to stabilize severe CVD.⁸⁸ Most of the volunteer patients with CVD responded to intensive counseling, and those who sustained plant-based nutrition for a mean of 3.7 years experienced a much lower rate of subsequent cardiac events than the nonadherent patients. This dietary approach to treatment provides proof of concept that a low-fat, plant-based diet can, on its own, produce meaningful symptom improvement in patients and deserves a wider test to see if adherence can be sustained in broader populations.⁹²

Lifestyle Heart Trial

In the Lifestyle Heart Trial, a prospective, randomized, controlled trial to determine whether comprehensive lifestyle changes affect coronary atherosclerosis after one year, n=28 patients were assigned to an experimental group (low-fat vegetarian diet, smoking cessation, stress management training, and moderate exercise), and n=20 to a usual-care control group.¹⁷³ A total of 195 coronary artery lesions were analyzed by quantitative coronary angiography. The average percentage diameter of stenosis regression was from 40.0 (SD 16.9)% to 37.8 (16.5)% in the experimental group yet progressed from 42.7 (15.5)% to 46.1 (18.5)% in the control group.¹⁷³ When only lesions greater than 50% stenosed were analyzed, the average percentage diameter stenosis regressed from 61.1 (8.8)% to 55.8 (11.0)% in the experimental group and progressed from 61.7 (9.5)% to 64.4 (16.3)% in the control group.¹⁷³ Overall, angiographic findings in the experimental group following a comprehensive lifestyle program found regression in 82% and less progression of angiographic stenosis compared to a control group following usual care after only one year, without the use of lipid-lowering drugs.¹⁷³

Patients in the experimental group sustained a weight loss of 5.8 kg (12.8 lbs) at 5 years; weight in the control group did not change significantly from baseline.¹⁷³ LDL levels were decreased at 5 years by 20% below baseline in the experimental group and 19.3% in the control group. HDL levels and blood pressure did not differ between the 2 groups.¹⁷³ Reported frequency of angina at 5 years decreased 72% in the experimental group and 36% in the control group perhaps by changing platelet endothelial interactions, vasomotor tone, or other dynamic characteristics of stenoses.¹⁷³ Cardiac events occurred significantly more frequently in the control group compared with the experimental group during the 5-year follow-up (risk ratio for any event for the control group=2.47, 95% CI 1.48-4.20).¹⁷³

The LDL reductions seen at 5 years are comparable to those achieved with lipid-lowering drugs in an ambulatory population. The study was relatively small, though provided a promising proof-of-concept path forward to halting the natural progression of coronary atherosclerosis and reducing cardiac symptoms and events.¹⁷³

CVD and Plant-Based Diets: A Summary of Key Randomized Trials, Systematic Reviews, and Meta-Analyses Studies

Beyond the work on diet and disease treatment, we explored the growing body of research examining the role of plant-based diets on the prevention of various forms of cardiovascular disease and extracted data from our strongest studies, the details of which are in Appendix Table 1 below. Of the 13 studies reviewed, four were randomized controlled trials,^{127, 162, 187, 188} and nine were a mix of systematic reviews and/or meta-analyses.^{124, 174, 189–195} Multiple studies examined the effect of plant-based diets on risk factors like anthropometric measurements and blood lipids,^{127, 162, 187, 188, 190–192, 194} while other studies examined the effects of plant-based diets on cardio- and cerebrovascular disease incidence and mortality.^{124, 174, 189, 193, 195}

Many studies examining plant-based diets and anthropometric and blood measurements showed a beneficial effect of plant-based diets. Mishra et al. found that an 18-week low-fat vegan diet intervention significantly improved BMI and cholesterol markers compared to the control group.¹²⁷ Macknin et al. found that both children and their parents had reductions in weight and blood risk markers for cardiovascular disease after four weeks on a low-fat, plant-based (PB) diet.¹⁶² The plant-based diet also outperformed the American Heart Association’s dietary recommendations in terms of blood markers and weight loss. Shah et al. confirmed these findings, showing superior improvements to CVD risk profiles in those assigned a PB dietary intervention.¹⁸⁸ The CARDIVEG study showed similar weight and blood lipids reductions between Mediterranean and vegetarian diets, though vegetarian diets showed a more drastic drop in LDL-cholesterol.¹⁸⁷ In meta-analyses, findings of reduced weight and blood lipids were mostly confirmed, except for in Lopez et al., where beneficial effects of PB diets were only found in blood pressure reduction in individuals with >130 mmHg systolic blood pressure at baseline.¹⁹⁴

As Aggarwal et al. found in their 2018 systematic review, weight management is pivotal among lifestyle modifications in managing heart failure.¹⁹⁶ A cross-sectional study corroborates this and suggests that a plant-based diet is a more important intervention.¹¹⁸ Several studies show that those on plant-based diets significantly lower systolic and diastolic blood pressure and significantly lower odds of hypertension (0.37 and 0.57, respectively) compared to non-vegetarians, which was achieved with the use of fewer antihypertensive medications and with a lower blood pressure reading.^{131, 197–202}

For studies examining incidence and mortality from various forms of CVD, there seems to be consistency in risk reduction for IHD but conflict in results involving other forms of CVD. Kwok et al. found significant reduction in risk for IHD in vegetarians, but this was primarily observed in Adventist Health Cohorts.¹⁸⁹ Dinu et al. confirmed these results, finding a significant risk reduction of IHD and a non-significant risk reduction for cerebrovascular disease in vegetarians.¹²⁴ A systematic review on heart failure presented suggestive evidence that risk of heart failure was decreased in vegetarian populations in multiple cohort studies.¹⁷⁴ Another study by Glenn et al. found no reduction in risk with vegetarian diets and stroke but a significant risk reduction in coronary heart disease incidence and mortality.

The Complete Health Improvement Program (CHIP), which centers on a whole food, plant-based eating pattern, has demonstrated rapid and meaningful reductions in chronic disease risk factors using lifestyle intervention centering on a plant-based diet. A total of 1003 people (aged 56.3 ± 12.1 years, 68% female) participated in one of 27 CHIP interventions throughout Canada between 2005 and 2011. Significant overall reductions (P<0.001) were recorded in the participants’ BMI (-3.1%), systolic blood pressure (-7.3%), diastolic blood pressure (-4.3%), total cholesterol (-11.3%), low-density lipoprotein cholesterol ([LDL-C] -12.9%), triglycerides (-8.2%), and fasting blood sugar (-7.0%). Participants with the highest classifications of these markers at program entry experienced approximately 20% reductions in these measures in 30 days.²⁰³ Encouragingly, protective effects from plant-based diets may mitigate genetic susceptibility to CVD from obesity.

Conclusion

Modern cardiology has had significant success in managing the acute and potentially fatal presentations of CVD, but efforts have been unsuccessful in halting the disease, addressing potential methods to halt CVD progression, and managing a worldwide epidemic.⁸⁸ Nutritional and other lifestyle medicine methods applied in an intensive or interventional manner similar to other CVD treatments with a focus on prescription of a plant-predominant diet would benefit patients as part of a comprehensive treatment plan for individual and population health.²⁰³

 

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