Can a plant-based diet reverse heart disease?

The objection

“Diet might help a little, but coronary heart disease only goes one way. The reversal stories rest on a few tiny studies of highly motivated volunteers, while statins, stents and bypass surgery have been tested in far bigger trials. Tell heart patients they can eat their way out of it and some of them will give up treatment that works.”

The answer

Doctors have tested that belief, though only in small numbers of patients. In Dean Ornish’s Lifestyle Heart Trial, 48 patients with moderate to severe coronary heart disease received either usual care or a whole-food vegetarian diet with about 10% of its calories from fat, combined with exercise, stress management, stopping smoking and group support. Among the 35 patients who had a five-year angiogram, 20 on the programme and 15 on usual care, the average narrowing of the programme group’s arteries had eased by 3.1 percentage points while the control group’s worsened by 11.8, a gap unlikely to be down to chance (P=.001; JAMA, 1998) [1]. Over those five years the 20 control patients had 45 cardiac events between them, against 25 among the 28 on the programme, a ratio of event rates for usual care of 2.47 (95% CI 1.48 to 4.20), counting repeat events per patient, which the paper calls a risk ratio [1].

The change had started early. After one year the average narrowing had gone from 40.0% to 37.8% in the programme group and from 42.7% to 46.1% in the control group, and 82% of programme patients had moved towards regression (Lancet, 1990) [2].

The trial’s own report also shows its limits [1]. The 48 were the patients who agreed to take part after 93 eligible people had been randomly assigned to the two groups and then invited, and about half of each group declined, so the groups compared were volunteers; 13 of the 48 had no five-year angiogram. Because the diet came bundled with exercise, stress management and group support, the trial can’t say how much of the benefit came from food, and nonfat dairy was part of the diet. Ornish and several of his co-authors were based at the Preventive Medicine Research Institute in Sausalito, California, so the programme was tested by its own team [1]. In the trial’s favour, the angiograms were analysed by people who didn’t know which group each patient was in.

The trial ran from 1986 to 1992, so it compared the programme with the usual care of that time, and 9 of the 15 control patients who finished took cholesterol-lowering drugs, while none of the programme group did [1]. Most of the events were hospital admissions, many of them for procedures such as angioplasty, and heart attacks and deaths were too few to compare. In the table the events column gives the programme’s 28 patients first and the 20 on usual care second, and the rate ratios compare usual care with the programme. Some patients had more than one event, so the ratios compare numbers of events per person-year of follow-up:

Over five years (1998)	Events	Rate ratio	95% CI
Any cardiac event	25 v 45	2.47	1.48 to 4.20
Cardiac hospital admissions	23 v 44	2.62	1.55 to 4.55
Angioplasty	8 v 14	2.40	0.939 to 6.60
Bypass surgery	2 v 5	3.43	0.561 to 36.0
Heart attack	2 v 4	2.74	0.393 to 30.3
Death	2 v 1	0.685	0.012 to 13.2

Hospital admissions include heart attacks, angioplasty and bypass operations [1]. Where an interval runs from below 1 to above it, as it does in every row after the first two, the trial could not rule out no difference, although the paper still reports the angioplasty result as significant (P<0.05) [1].

Did Esselstyn’s diet reverse heart disease?

Caldwell Esselstyn’s 2014 study can’t show that his diet reversed heart disease, because it had no randomised control group, though the authors reported a low rate of further cardiac events among the patients who kept to it. His team at the Cleveland Clinic’s Wellness Institute counselled 198 patients with established cardiovascular disease to cut out meat, fish, dairy and added oil, along with processed foods, sugar, refined carbohydrates, excess salt, fruit juice, avocado and nuts, and encouraged physical activity, alongside their usual cardiac care (Journal of Family Practice, 2014) [3] [4]. Of the 177 who kept to the diet for an average of 3.7 years, the authors counted one major cardiac event that they judged to be recurrent disease, a stroke [3], and the British Heart Foundation reports that most of them reported fewer symptoms and 22% had reversal confirmed by test results (2023) [4]. Of the 21 who didn’t keep to it, 13 had adverse events, which the paper counts on a different basis from the adherent group’s recurrent events, so the two figures can’t be set against each other [3]. The patients were volunteers who wanted to change to this way of eating, and as the British Heart Foundation’s dietitian points out, nobody knows what a diet of similar nutritional value that included animal products would have done, or how much came from the exercise and the weight most participants lost [4].

Does the British Heart Foundation recommend a plant-based diet?

The British Heart Foundation’s dietitian says we should all eat more fruit, vegetables, wholegrains and plant sources of protein, and counts both the traditional Mediterranean diet and the UK’s Eatwell Guide as plant-based, but she is more cautious about reversal [4]. On a page last updated in 2023, Victoria Taylor writes that changing diet and lifestyle, along with prescribed medication, helps slow the progression of coronary heart disease, that reversal “is another matter”, and that much larger numbers of people would have to be studied before official guidelines changed [4]. She adds that a well-balanced vegan diet can also be a healthy way to eat, that plant-based foods aren’t automatically healthy, and that a Mediterranean-style diet may be easier to follow than a strict vegan one [4]. A 2024 meta-analysis drawing on up to nine cohort studies and 359,740 people backs her warning: diets scoring higher for healthy plant foods were linked with less cardiovascular disease (hazard ratio 0.94 per standard deviation of the score, 95% CI 0.91 to 0.98), and diets scoring higher for less healthy plant foods with slightly more (1.03, 1.01 to 1.06), associations from observational studies that can’t prove cause (Progress in Cardiovascular Diseases, 2024) [16].

The Mediterranean diet has been tested in a much larger trial of heart patients. CORDIOPREV randomly assigned 1,002 people with coronary heart disease in Córdoba, Spain, to a Mediterranean diet or a low-fat diet and followed them for seven years (Lancet, 2022) [5]. Major cardiovascular events struck 87 patients on the Mediterranean diet and 111 on the low-fat diet, crude rates of 28.1 and 37.7 per 1,000 person-years, with adjusted hazard ratios between 0.719 and 0.753 depending on the model [5]. The benefit showed in men but not in the 175 women, the patients knew which diet they were on, and the funders included two foundations linked to olive oil [5]. The same trial measured the thickness of the carotid artery walls in the neck, a secondary outcome, in 939 of its patients: on the Mediterranean diet it fell by 0.027 mm over five years and by 0.031 mm at seven, while on the low-fat diet it didn’t change (Stroke, 2021) [15]. That low-fat diet took 28% of its calories from fat, against about 10% in Ornish’s trial, so the two trials weren’t testing the same diet [1] [15]. Neither CORDIOPREV nor the Lifestyle Heart Trial compared a vegan diet with a Mediterranean one, so these trials can’t rank them.

Does a plant-based diet lower the risk of heart disease?

Vegetarians get less heart disease than meat-eaters in long-running cohort studies, though the evidence for vegans alone is thinner and none of it can prove cause and effect. That matters because ischaemic heart disease is the world’s biggest killer: the World Health Organization (2026) says it accounts for 16% of the world’s deaths, and it caused 9.5 million deaths in 2023 [6]. A 2023 meta-analysis of 13 cohort studies with 844,175 participants put the relative risk of ischaemic heart disease at 0.79 (95% CI 0.71 to 0.88) for vegetarians against non-vegetarians, and at 0.82 (0.68 to 1.00) for vegans, an estimate from six studies that can’t rule out no difference (European Journal of Nutrition, 2023) [7]. Its authors judged the link between vegetarian diets and less heart disease probably causal, though they rated the studies’ risk of bias moderate to serious, and they found no clear difference in total stroke (0.90, 0.77 to 1.05) [7].

The UK’s EPIC-Oxford study gives absolute figures. It followed 48,188 people without heart disease or stroke for 18.1 years, and after allowing for social and lifestyle factors the vegetarians, vegans included, had a 22% lower rate of ischaemic heart disease than the meat-eaters (hazard ratio 0.78, 95% CI 0.70 to 0.87), about 10 fewer cases per 1,000 people over ten years (BMJ, 2019) [8]. Allowing also for self-reported high cholesterol, high blood pressure, diabetes and body mass index brought the hazard ratio to 0.90 (0.81 to 1.00), which can’t rule out no difference [8]. In this study the vegetarians also had a 20% higher rate of stroke (hazard ratio 1.20, 1.02 to 1.40), about three more cases per 1,000 over ten years, mostly the haemorrhagic kind [8], and the wider health record of plant-based diets covers that finding too.

Randomised trials point to ways the diet could help. A 2023 meta-analysis of 30 trials with 2,372 participants found that vegetarian and vegan diets lowered LDL cholesterol by 0.30 mmol/L compared with omnivorous diets, about 10% from baseline (European Heart Journal, 2023) [9]. Most of those trials were small and lasted under a year, with signs that small studies were overrepresented, and the authors judged statins better at lowering cholesterol while expecting the diet and the drugs to work well together [9]. The diets also lowered apolipoprotein B, the protein on the cholesterol-carrying particles that build up in artery walls, by 12.92 mg/dL (95% CI 3.20 to 22.63), and the authors concluded that plant-based diets have the potential to lessen that build-up and so reduce the risk of cardiovascular disease [9].

In people who already had coronary artery disease and were on guideline-directed medical treatment, the EVADE CAD trial randomly assigned 100 patients to eight weeks of a vegan diet or the American Heart Association’s recommended diet, with groceries provided (Journal of the American Heart Association, 2018) [10]. High-sensitivity C-reactive protein, a marker of inflammation and of the risk of major cardiovascular events, came out 32% lower on the vegan diet, and LDL cholesterol was 13% lower, short of the strict bar the trial set for significance [10]. A blood marker measured over eight weeks can’t show what would happen to heart attacks or deaths.

Is it safe to change your diet if you have heart disease?

It can be, provided your doctor or pharmacist knows first and you keep taking prescribed medicine. Esselstyn’s patients stayed on their usual cardiac care [3] and the EVADE CAD patients on their guideline-directed treatment [10]. The NHS says to talk to a doctor or pharmacist before stopping a statin, and lists grapefruit and grapefruit juice among the things that can increase its side effects [11]. If you take warfarin, talk to your doctor before any big change to your diet, because foods high in vitamin K, such as broccoli, spinach and other green leafy vegetables, can affect how it works; you can still eat them, with advice from your warfarin clinic [12]. If you cut out all animal foods you’ll need a reliable source of vitamin B12, such as fortified breakfast cereals or soya drinks or a supplement, because the NHS says vegan sources are limited [17]. If you take medicine for blood pressure or type 2 diabetes, tell your GP before you change how you eat, and don’t change or stop any medicine without speaking to them first. After a heart attack, the NHS says, you’ll usually be referred to cardiac rehabilitation to help with your recovery [13].

No diet is a substitute for emergency care. The NHS says to call 999 for chest pain that feels tight or like squeezing on your chest, or that spreads to your arms, neck or jaw [13], and outside the UK the same goes for your local emergency number. In the UK, the British Heart Foundation’s Heart Helpline is free on 0808 802 1234, 9am to 5pm on weekdays except bank holidays, and its cardiac nurses can help with questions about heart and circulatory conditions, including medicines and their side effects [14].