Protocol · graded by use, three uses
Whole-food plant-based diet
Graded on: LDL Low-density lipoprotein cholesterol, the cholesterol fraction most closely tied to plaque in the arteries. cholesterol (and HbA1c A blood test that reflects average blood sugar over the previous two to three months. in type 2 diabetes).
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How this letter has changedLatest: October 2026 · First graded.
The plant-based diet page carried a Grade B with no record behind it and no citation. It now has a graded record. A meta-analysis A study that pools the numbers from several trials into one combined estimate. of 30 randomized trials found vegetarian and vegan diets lowered LDL cholesterol by 0.30 mmol/L against omnivorous diets (Koch et al., Eur Heart J, 2023; PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 37226630), and a meta-analysis of 7 trials found HbA1c 0.40 percentage points lower in type 2 diabetes (Guest et al., Adv Nutr, 2024; PMID 39415400): both Grade B, on established surrogates. Heart attacks, strokes and mortality are Grade D: no randomized trial has tested the diet on its own against them, and the Cochrane review found none of its trials reported a cardiovascular event (Rees et al., Cochrane Database Syst Rev, 2021; PMID 33629376). Against other healthy diets, the LDL difference was small or absent.PMID 37226630 PMID 39415400 PMID 33629376
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This diet is mostly plants: vegetables, fruit, beans, whole grains, nuts and seeds. Meat, eggs, dairy and junk food are cut back or left out. In many trials, it lowered LDL cholesterol more than a usual diet with meat. In people with type 2 diabetes, it lowered average blood sugar. No trial has tested if it prevents heart attacks or deaths. Next to other healthy diets, the cholesterol gap was small or gone.
The B is shared by two of the three uses graded on this record, each on its own evidence. The other one carries its own letter.
This record carries a separate letter for each thing it has been measured on. The headline grade is the best of them, and it does not transfer to the others.
Koch et al. (Eur Heart J, 2023; PMID 37226630): 30 randomized trials, LDL cholesterol 0.30 mmol/L lower against omnivorous diets. Wang et al. (J Am Heart Assoc, 2015; PMID 26508743): a separate pooling, 0.34 mmol/L lower. Landry et al. (JAMA Netw Open, 2023; PMID 38032644): identical twins, 13.9 mg/dL lower after 8 weeks. Replicated The same finding reproduced by a separate research group. A result seen once can be chance or bias; a replicated one is harder to explain away. by independent groups on an established surrogate: B. Against other active diets the Cochrane review (Rees et al., 2021; PMID 33629376) found little or no LDL difference, so the comparison this letter describes is a typical diet that includes meat.
Guest et al. (Adv Nutr, 2024; PMID 39415400): 7 randomized trials, 770 adults, HbA1c 0.40 percentage points lower, moderate certainty. Viguiliouk et al. (Clin Nutr, 2019; PMID 29960809): 9 trials, 664 participants, 0.29 lower, moderate certainty. Barnard et al. (Diabetes Care, 2006; PMID 16873779): 0.96 against 0.56 percentage points over 22 weeks, not significant when every participant was counted and significant among those whose medication did not change; the trial was led by researchers from the Physicians Committee for Responsible Medicine, which advocates plant-based diets. Lee et al. (PLoS One, 2016; PMID 27253526): an independent Korean trial, 0.5 against 0.2 percentage points over 12 weeks. HbA1c is an established surrogate and the effect is replicated across groups: B. Part of the effect may come from weight loss, which the vegan arms showed more of.
No randomized trial has tested the diet on its own against heart attacks, strokes or death. Rees et al. (Cochrane, 2021; PMID 33629376) found none of its trials reported a cardiovascular event. The evidence on these outcomes is observational Research that watches what people already do rather than assigning a treatment. It can show that two things travel together, not that one causes the other.: Wang et al. (Nutr J, 2023; PMID 37789346) found higher adherence to healthy plant-based patterns associated with lower cardiovascular disease and mortality, and unhealthy plant-based patterns with higher risk. EBL does not grade on population studies. Route 1 No human randomized trial has been run, so the record rests on animal or mechanistic evidence only. One of the two routes to the lowest letter on EBL's scale.: the trial has not been run.
LDL cholesterol compared with a typical omnivorous diet (B), and HbA1c in adults with type 2 diabetes (B). No randomized trial has tested the diet on its own against heart attacks, strokes or death (D).
Why this gradeThe reasoning, and what the grade does not cover.
Grade B on LDL cholesterol. A meta-analysis of 30 randomized trials found vegetarian and vegan diets lowered LDL cholesterol by 0.30 mmol/L and apolipoprotein B by 12.9 mg/dL against omnivorous diets (Koch et al., 2023; PMID 37226630), an earlier pooling by a different group found 0.34 mmol/L (Wang et al., 2015; PMID 26508743), and a randomized trial in identical twins found 13.9 mg/dL (Landry et al., 2023; PMID 38032644). LDL cholesterol is an established stand-in for cardiovascular outcomes, and the effect is replicated across independent groups. HbA1c in type 2 diabetes is graded B as its own use.
WHY NOT Ano randomized trial has tested the diet on its own against heart attacks, strokes or death; the Cochrane review found none of its trials reported a cardiovascular event (Rees et al., 2021; PMID 33629376).
WHAT THIS GRADE DOES NOT COVERthe comparison with other healthy diets, where the same Cochrane review found little or no LDL difference; a vegan diet built on refined grains and sugar, which is not the diet the trials tested; and mortality or longevity, graded D below.
A grade describes the human evidence for a named use. It is not advice, and it is not a judgment on any individual prescription. How the letters are decided →
No prominent contraindication A condition or medication that makes a treatment unsafe or unsuitable for a particular person.. Plants supply no vitamin B12. People taking medicines that lower blood sugar or blood pressure can see those values fall when the diet changes, which the diabetes trials handled by adjusting medication.
The evidence, in fullTen papers, each linked to its PubMed record.
Koch et al. (Eur Heart J, 2023; PMID 37226630): meta-analysis of 30 randomized trials; vegetarian and vegan diets lowered LDL cholesterol by 0.30 mmol/L and apolipoprotein B by 12.9 mg/dL compared with omnivorous diets, consistent across age, continent, duration and health status. Wang et al. (J Am Heart Assoc, 2015; PMID 26508743): meta-analysis of randomized trials; LDL cholesterol 0.34 mmol/L lower. Landry et al. (JAMA Netw Open, 2023; PMID 38032644): 22 pairs of identical twins, one of each pair randomized to a healthy vegan diet and one to a healthy omnivorous diet for 8 weeks; LDL cholesterol 13.9 mg/dL lower on the vegan diet. Rees et al. (Cochrane Database Syst Rev, 2021; PMID 33629376): vegan diets against no or minimal intervention probably lower LDL cholesterol (0.22 mmol/L, moderate certainty), against other dietary interventions probably little or no difference; none of the included trials reported cardiovascular events. Type 2 diabetes: Guest et al. (Adv Nutr, 2024; PMID 39415400): 7 randomized trials, 770 participants; HbA1c 0.40 percentage points lower, moderate certainty. Viguiliouk et al. (Clin Nutr, 2019; PMID 29960809): 9 randomized trials, 664 participants; HbA1c 0.29 percentage points lower, moderate certainty. Barnard et al. (Diabetes Care, 2006; PMID 16873779): 99 adults with type 2 diabetes, low-fat vegan diet against the American Diabetes Association diet for 22 weeks. Lee et al. (PLoS One, 2016; PMID 27253526): an independent Korean trial of a brown-rice-based vegan diet against a conventional diabetic diet for 12 weeks; HbA1c fell 0.5 against 0.2 percentage points. Termannsen et al. (Obes Rev, 2022; PMID 35672940): 11 trials of vegan diets for at least 12 weeks in overweight or type 2 diabetes; body weight 4.1 kg, HbA1c 0.18 percentage points and LDL cholesterol 0.24 mmol/L lower. Hard outcomes, observational only: Wang et al. (Nutr J, 2023; PMID 37789346): cohort meta-analysis; higher adherence to healthy plant-based patterns associated with lower cardiovascular disease and mortality, unhealthy plant-based patterns with higher risk.
Measured outcome: LDL cholesterol or apolipoprotein B at baseline and after 8 to 12 weeks, the interval over which the trials reported their effect; HbA1c at baseline and 12 weeks in type 2 diabetes. Vitamin B12 status, because plants supply none. No trial has measured heart attacks, strokes or deaths, so these markers are the only endpoints The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score. this grade rests on.
Evidence notes: randomized trial, meta-analysis
Endpoint graded: LDL cholesterol (and HbA1c in type 2 diabetes) (surrogate)
Last reviewed: October 2026
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(vegan[tiab] OR vegetarian[tiab] OR "plant-based diet"[tiab] OR "whole-food plant-based"[tiab]) AND (LDL[tiab] OR "low-density lipoprotein"[tiab]) AND (randomized controlled trial[pt] OR meta-analysis[pt])Grades move when new trials publish. A free monthly email lists every grade EBL moved, with the reason and the trial behind it: the sign-up is on the Evidence Log →