TABLE 2.

Inclusion criteria, diet, and outcome ascertainment about the included studies¹

Reference	Inclusion/exclusion criteria	Definition of vegan diet by study	Diet ascertainment	Details of diets of those not adhering to vegan diet	Definition of outcome	Method of outcome ascertainment
Prospective cohort studies
Orlich et al., 2013 (24)	Exclusions: missing data for questionnaire return date, birth date, sex, or race (n = 1702); age younger than 25 years (n = 434); estimated energy intake (not including write-in items) <500 kcal/d or >4500 kcal/d; improbable response patterns (e.g., identical responses to all questions on a page) or >69 missing values in dietary data (n = 4961); non-US residents (n = 4108); or history of a specific prior cancer diagnosis (except nonmelanoma skin cancers) or of CVD (n = 11,956)	Vegans consumed eggs/dairy, fish, and all other meats less than 1 time/month	Self-administered quantitative FFQ. Usual dietary intake during the previous year was assessed at baseline by a self-administered quantitative FFQ of >200 food items. Dietary patterns were determined according to the reported intake of foods of animal origin	Nonvegetarians consumed nonfish meats 1 + time/month and all meats combined (fish included) 1 + time/week	Deaths associated with CHD were identified as ICD-10 I20–25	Mortality data through 31 December 2009, were obtained from the National Death Index. ICD-10 codes for the underlying cause of death were used for causal classification. Unnatural causes of death (ICD-10 letters U, V, W, X, and Y) were considered as censoring events. Deaths associated with IHD were identified as ICD-10 I20–25; CVD deaths, as those starting with the letter I; and cancer deaths, as those starting with the letter C
Tong et al., 2019 (23)	Men and women aged 35 to 59 who were registered with participating general practices, all of whom completed a full questionnaire on their diet, lifestyle, health characteristics, and medical history	Participants who did not eat meat, fish, dairy products, or eggs as self-reported through questions in the form of “Do you eat any meat (including bacon, ham, poultry, game, meat pies, sausages)?”	A full baseline questionnaire	Participants who reported eating meat, regardless of whether they ate fish, dairy, or eggs	CHD (ICD-9: 410–414 or ICD-10: I20–5), including acute myocardial infarction (ICD-9 410, ICD-10 I21); total stroke (ICD-9 430–1, 433–4, 436; ICD-10 I60–1, I63–4); ischaemic stroke (ICD-9 433–4, ICD-10 I63); haemorrhagic stroke (ICD-9 430–1, ICD-10 I60–1)	Participants were followed up via record linkage to records from the UK's health service up to 31 March 2016. Details of events, using the relevant ICD-9 or ICD-10 codes, were obtained from hospital records or death certificates
Key et al., 1999 (22)	Subjects were eligible for analysis if they were aged 16–89 y at recruitment, if they had not been diagnosed with cancer before recruitment (except nonmelanoma skin cancer), and if they provided enough information for classifying diet group and smoking category	People who reported that they did not eat any animal products	Self-reported consumption of meat or fish	The reference group (regular meat eaters) ate meat ≥1 time/week both	Defined by ICD-9 codes: Ischemic heart disease (ICD-9 410–414) & cerebrovascular disease (ICD-9 430–438)	The Adventist Mortality Study: record linkage and personal contact. The Health Food Shoppers Study & the Oxford Vegetarian Study cohort: record linkage with the National Health Service Central Register. The Adventist Health Study; record linkage with the California death certificate file, the USA National Death Index, and church records. The Heidelberg Study; the registrar's office of the last place of residence
Esselstyn et al., 2014 (12)	Self-selection of participants	Whole grains, legumes, lentils, vegetables, and fruit. Subjects were encouraged to take a multivitamin, vitamin B12 supplement & flax seed meal. Caffeine was excluded. Initially all added oils, nuts, processed foods, avocado, excess salt, sugary foods, and drinks were excluded	Self-report adherence to the diet	Not provided	Angina—no definition of CHD—as assessed in radiographic or stress tests	Self-report or, where participant dies, next of kin
Cross-sectional studies
Fontana et al., 2007 (28)	Vegan subjects were recruited by contacting The St. Louis Vegetarian Society and a Raw Food online magazine. These subjects were consuming a low-calorie low-protein vegan diet, composed of unprocessed and uncooked plant derived foods, for at least 2 years. The second group of subjects comprised endurance runners who were matched with the low-calorie, low-protein, vegan diet group on age, gender, and BMI, and were recruited by contacting local running clubs. The third group of subjects were healthy, sedentary nonobese (BMI 30 kg/m2) subjects, who were eating typical Western diets. These subjects were recruited by local advertising and were matched with the low-calorie, low-protein, vegan diet group on age, gender, and height	Subjects were excluded from the low-calorie, low-protein, vegan diet group if they ate: 1) animal products including meat, diary, and eggs; and 2) cooked and processed foods	Subjects were instructed by a research dietitian to record all food and beverage intake, including preparation methods and portion sizes, for 7 consecutive days. Measuring spoon and cup sets, and food diaries with a ruler imprinted on the back cover were provided to the participants to assist with portion size determinations. Supplements were not included in the diet records	1) Endurance runners matched on BMI with the low-calorie, low-protein, vegan group; or 2) nonobese, sedentary subjects consuming typical Western diets	IMT was measured in the anterior wall as the distance from the trailing edge of the adventitia to the leading edge of the intima media; and in the posterior wall as the distance from the leading edge of the intima-media to the trailing edge of the adventitia. The mean of 16 measurements was for the IMT. Examinations and image analyses were performed by a trained sonographer blinded to the subjects’ dietary habits	Carotid artery IMT, which correlates with coronary artery atherosclerosis, was determined by using high-resolution, real-time B-mode ultrasonography with an 11-MHz transducer to image the right and left common carotid arteries. Arteries were scanned in the longitudinal projections over an arterial segment that included 30 mm of the distal common carotid artery. IMT was measured in the anterior wall of the vessel as the distance from the trailing edge of the adventitia to the leading edge of the intima. The average of 16 measurements was taken as the mean IMT. Examinations and image analyses were performed by a trained sonographer who was not aware of subjects’ dietary habits
Randomized controlled trials
Shah et al., 2018 (25)	Patients from New York University Langone Medical Center with angiographically defined CAD (≥50% lesion in an artery with ≥2‐mm caliber). Exclusion criteria: 1) history of an eating disorder; 2) already on vegetarian or vegan diet; 3) steroids use or nonsteroidal anti‐inflammatory medications other than aspirin; 4) history of myocardial infarction or coronary artery bypass graft surgery in last 3 months; 5) presence of infection in last 3 months; and 6) have a planned staged coronary revascularization or other surgical procedure during study period. Potential participants were also excluded if they had a score of >4 on any of the motivational items or if the relative autonomy index (defined as average of answers for the 6 autonomous items—average of answers for the 6 controlled items) was ≤0 on a treatment self‐regulation questionnaire	Participants in the vegan diet group received 1 point for abstinence from each of the following: 1) meat/poultry/eggs; 2) dairy; and 3) seafood. Participants in the vegan diet group could earn up to 3 points on each of the two 24-hour dietary recalls, and a score of 5 to 6 was defined as adherent to the vegan diet for that week	Participants were instructed to fill out a 4-day food record during the 1 week before the 3 visits to the dietician	American Heart Association–recommended diet with a focus on low fat/fat-free dairy, fish 2+ times a week, and ≤5 oz of animal protein/day. Subjects were provided with groceries, tools to measure dietary intake, and dietary counseling	Secondary outcome: clinical events (e.g., myocardial infarction)	Endothelium activity was measured, as an exploratory end point, in a subset of participants using the EndoPat Device (Itamar Medical Ltd.). Major adverse cardiovascular and cerebrovascular event was defined as the composite of all-cause mortality, myocardial infarction, stroke or transient ischemic attack, and repeat coronary revascularization. Participants were directly asked about interim clinical events during study visits. Source documents were collected, and the reported events were adjudicated by the study investigators blinded to treatment allocation
Wright et al. 2017 (26)	Inclusion criteria: age 35–70 and either obese (BMI 30 kg/m2) or overweight (BMI 25 kg/m2), with a diagnosis of CHD, hypertension, type 2 diabetes or hypercholesterolemia. Exclusion criteria: diagnoses of life-threatening comorbidities; thyroid disease; coronary artery bypass grafting within 6 weeks; myocardial infarction within 1 month; angioplasty within 6 months; >50% stenosis of the left main coronary artery; unresponsive congestive heart failure; malignant uncontrolled arrhythmias; homozygous hypercholesterolemia; severe mental health disorders; current alcohol or drug misuse; currently smoking; currently pregnant or breastfeeding women, prior bariatric surgery, other conditions that directly affect weight (e.g., lead toxicity, malignancy)	Low-fat, plant-based diet. Included whole grains, legumes, vegetable, and fruits. Participants were advised to eat until satiation. No restriction on calorie intake	3-day recall forms to track dietary indiscretions and exercise	Normal diet: no details reported	Cardiovascular events	Notification on transfer to higher cardiac-related care

¹CAD, coronary artery disease; CHD, coronary heart disease; CVD, cardiovascular disease; ICD-9, International Statistical Classification of Diseases, 9th Revision; ICD-10, International Statistical Classification of Diseases, 10th Revision; IHD, ischemic heart disease; IMT, intima media thickness.