Does a vegan diet lower cholesterol?

Yes, and the evidence is unusually clean. In 22 pairs of identical twins, the vegan twin's LDL was 13.9 mg/dL lower than their own genetically identical co-twin after eight weeks. Because genetics and upbringing are controlled by the design, that finding is hard to explain any other way, though calories were not matched so part of it runs through a 1.9 kg weight difference.

Do vegans live longer?

The two large cohorts disagree, and this is the honest answer rather than a hedge. A North American Adventist cohort found 12 percent lower all-cause mortality for vegetarians overall, with the vegan estimate not reaching significance. A UK pooled analysis built around a comparable health-conscious meat-eating comparison group found no difference at all. Both are observational and neither settles it.

What about the stroke finding?

EPIC-Oxford found vegetarians had 20 percent higher total stroke over 18 years, driven by haemorrhagic stroke, about 3 more cases per 1,000 people over ten years. It is in the paper's published title and it is routinely omitted from summaries. Unlike the heart disease benefit in the same paper, it did not attenuate when disease risk factors were adjusted for. The mechanism is unestablished and a cohort cannot establish one.

Is the hip fracture risk real?

It is the largest adverse signal in this pattern: an adjusted hazard ratio of 2.31 in vegans, equal to 14.9 more hip fractures per 1,000 people over ten years. Adventist data indicates the excess is confined to those not taking both calcium and vitamin D, which makes it a solvable problem. Solving it means actually supplementing and testing, not assuming your diet covers it.

Can I build muscle on it?

Yes, and you have to plan the protein rather than expect it. Plant proteins run lower in leucine and lower on digestibility scores, so reaching a high target needs deliberate use of legumes, soy and isolated protein. The lean mass data inside these trials is too thin to quote, which is itself worth knowing.

Plant-forward10 human studies cited

Vegan and vegetarian

Written by Aaron CuhaReviewed Sep 2026

Also called: Plant-based, Plant-exclusive, Vegetarian

Strong randomised data on LDL and weight, and the best trial is 22 pairs of identical twins. The cohorts disagree with each other on mortality, and the two findings advocates leave out are stroke and hip fracture.

What it actually is

Vegan excludes all animal foods. Vegetarian excludes meat and usually fish while allowing dairy and eggs. The distinction matters more than it looks, because in the mortality data the patterns behave differently and the strictest version is not the one with the best numbers.

The mechanism its advocates propose

Lower saturated fat and no dietary cholesterol lower LDL. High fibre and high volume at low energy density reduce intake without hunger. Absence of processed meat removes an exposure associated with colorectal cancer. All three are mechanistically sound and the first two are measurable within weeks.

What happened when calories were controlled

Strongest design available: ad libitum

Both groups ate freely. A difference here is the diet and its effect on appetite and adherence combined, which is a fair question but a different one.

Almost never, which is the central caveat of this literature. The best randomised trials provided food but did not match calories, so part of every result runs through weight loss rather than through the pattern itself.

Landry 2023, the Stanford twin study, is the strongest design here: 22 pairs of identical twins, one twin per pair randomised to healthy vegan or healthy omnivorous for eight weeks, meals delivered for the first four. Vegan twins against their own co-twins: LDL minus 13.9 mg/dL, fasting insulin minus 2.9 microIU/mL, body weight minus 1.9 kg. Genetics and shared upbringing are controlled, which is rare and genuinely strong. Calories were not matched, so part of the LDL and insulin difference runs through the 1.9 kg.
Kahleova 2020 randomised 244 overweight adults to a low fat vegan diet or to make no dietary changes at all. Weight minus 5.9 kg, HOMA-IR minus 1.3, thermic effect of food plus 14.1 percent. This compares a diet against no diet. It establishes that a supported intervention beats changing nothing, and says nothing about the vegan pattern against another active pattern.
Barnard 2006, 99 adults with type 2 diabetes, vegan against an American Diabetes Association guideline diet for 22 weeks, food not provided. HbA1c across all participants minus 0.96 against minus 0.56 percentage points, p = 0.089, not significant. Weight minus 6.5 against minus 3.1 kg, p < 0.001. Excluding those who changed medication the HbA1c difference reached significance, which is a legitimate analysis and a secondary one.
Barnard 2022 is the only direct randomised comparison of vegan against Mediterranean in this evidence base: 62 adults, crossover, 16 weeks per arm. Vegan won on weight, minus 6.0 kg against zero, and on LDL. Mediterranean won on systolic blood pressure by 5.9 mmHg, p = 0.02. Insulin resistance was not significantly different. It was run by a plant-based advocacy organisation and still published the blood pressure result against its own pattern, which is worth noting.

What happened when people just ate it

Adherence is better than the stereotype suggests. In the Barnard diabetes trial, all 99 completed 22 weeks, and at 74 weeks 86 percent of the vegan arm and 90 percent of the guideline arm were still in. Diet-specific adherence criteria were met by 67 percent of the vegan arm against 44 percent of the guideline arm. But the 74-week results are largely null on the headline comparisons: weight minus 4.4 against minus 3.0 kg (p = 0.25) and HbA1c minus 0.34 against minus 0.14 percentage points (p = 0.43). The lipid advantages persisted where medication had not changed. That is the pattern across this literature: strong early, attenuating, with lipids the most durable.

Protein, and whether it confounds the result

Reaching a high protein target is harder here and it is not impossible. The practical constraints are that plant proteins are generally lower in leucine, that digestibility scores run lower, and that hitting 150 to 200 g a day requires deliberate planning around legumes, soy and isolated protein powders rather than happening by accident. Lean mass data in these trials is thin: one of the main vegan trials reported 3.9 kg of fat mass loss out of a 5.9 kg total weight loss and did not decompose the remainder, so no lean mass figure can be quoted from it. Anyone combining this pattern with a weight loss drug or a training programme should treat protein as the thing to solve first.

The measured intakes behind the protein figures are on the protein page.

What reliably moves

Marker	Direction	From
LDL cholesterol	Down, reliably	Minus 13.9 mg/dL against an identical twin at eight weeks. This is the most robust finding in the pattern and the twin design makes it hard to explain away.
Body weight	Down	Minus 1.9 kg against a co-twin in eight weeks, minus 5.9 kg against no intervention in sixteen weeks, minus 6.5 kg against a guideline diet in 22 weeks.
Fasting insulin and HOMA-IR	Down	Minus 2.9 microIU/mL against a co-twin; HOMA-IR minus 1.0 to minus 1.3 across trials. Change in HOMA-IR correlated with change in BMI and visceral fat, so part of it is the weight.
Vitamin B12	Down without supplementation, and this is not contested	52 percent of British vegan men were deficient by serum B12 in a cohort where supplementation was not universal, while a Swiss cohort with widespread supplement use showed low deficiency prevalence. Status tracks supplementation, which means this is entirely solvable and must actually be solved.
Zinc and iodine	Down	Zinc was the leading deficiency in Swiss vegans at 47 percent prevalence. Iodine measured low in vegan cohorts in both Norway and Boston, without measured thyroid dysfunction in the Boston sample.
Long-chain omega-3	Down, and it does not recover	EPA and DHA proportions are lower and do not improve with longer time on the diet, which argues against adaptation and for either algal supplementation or acceptance of a lower index.

Long term, and hard outcomes

This is where the pattern gets genuinely complicated, and where most summaries stop reading. Two large cohorts disagree. The Adventist Health Study 2, 73,308 people, found all-cause mortality hazard ratio 0.88 for vegetarians combined, with the vegan estimate at 0.85 and not significant while the pesco-vegetarian estimate at 0.81 was. A pooled analysis of two UK cohorts, 60,310 people including 2,228 vegans, deliberately built around a comparable health-conscious meat-eating reference group, found no difference in overall mortality at all: vegetarians 1.02, fish eaters 0.96, low meat eaters 0.93. Neither settles it, and the most obvious structural difference is the comparator. Two findings run against the pattern and are routinely omitted. EPIC-Oxford found vegetarians had 22 percent lower ischaemic heart disease, which partly attenuated on adjustment for cholesterol, blood pressure, diabetes and BMI, and 20 percent higher total stroke driven by haemorrhagic stroke, which did not attenuate. The stroke finding is in the paper's published title. And the fracture data is the starkest number in this pattern: adjusted hip fracture hazard ratio 2.31 in vegans against meat eaters, equal to 14.9 more cases per 1,000 people over ten years. Adventist data indicates that excess is confined to those not taking both calcium and vitamin D, which makes it a solvable problem rather than an argument against the diet, and it has to be solved rather than waved away.

Citations

Human2023
Cardiometabolic effects of omnivorous vs vegan diets in identical twins: a randomized clinical trial
JAMA Network Open
22 pairs of identical twins, one twin per pair randomised for eight weeks. Vegan against co-twin: LDL minus 13.9 mg/dL, fasting insulin minus 2.9 microIU/mL, weight minus 1.9 kg. Calories not matched. Lead author disclosed funding from Beyond Meat outside the submitted work.
Human2020
Effect of a low-fat vegan diet on body weight, insulin sensitivity, postprandial metabolism, and intramyocellular and hepatocellular lipid levels in overweight adults
JAMA Network Open
244 overweight adults randomised to a low fat vegan diet or to make no dietary change. Weight minus 5.9 kg, HOMA-IR minus 1.3, thermic effect of food plus 14.1 percent. Conducted by an organisation that advocates plant-based diets; this compares a diet against no diet.
Human2006
A low-fat vegan diet improves glycemic control and cardiovascular risk factors in a randomized clinical trial in individuals with type 2 diabetes
Diabetes Care
99 adults with type 2 diabetes, vegan against an ADA guideline diet, 22 weeks. HbA1c minus 0.96 against minus 0.56 percentage points, p = 0.089, not significant across all participants. Weight minus 6.5 against minus 3.1 kg, p < 0.001.
Human2009
A low-fat vegan diet and a conventional diabetes diet in the treatment of type 2 diabetes: a randomized, controlled, 74-wk clinical trial
American Journal of Clinical Nutrition
The 74-week extension, and largely a null on the headline comparisons. Weight minus 4.4 against minus 3.0 kg (p = 0.25) and HbA1c minus 0.34 against minus 0.14 (p = 0.43). Lipid advantages persisted where medication had not changed.
Human2019
Risks of ischaemic heart disease and stroke in meat eaters, fish eaters, and vegetarians over 18 years of follow-up: results from the prospective EPIC-Oxford study
BMJ
48,188 participants, 18.1 years. Vegetarians 22 percent lower ischaemic heart disease (HR 0.78), attenuating to 0.90 on adjustment for cholesterol, blood pressure, diabetes and BMI. Vegetarians 20 percent higher total stroke (HR 1.20, 1.02 to 1.40), driven by haemorrhagic stroke, and that did not attenuate. Observational.
Human2013
Vegetarian dietary patterns and mortality in Adventist Health Study 2
JAMA Internal Medicine
73,308 participants, 2,570 deaths. All vegetarians combined HR 0.88 (0.80 to 0.97). Vegans 0.85 (0.73 to 1.01), not significant. Pesco-vegetarians 0.81 (0.69 to 0.94). Observational, single baseline food frequency questionnaire.
Human2016
Mortality in vegetarians and comparable nonvegetarians in the United Kingdom
American Journal of Clinical Nutrition
The UK null that deserves equal prominence. 60,310 people including 2,228 vegans, 5,294 deaths. All-cause mortality against regular meat eaters: vegetarians HR 1.02 (0.94 to 1.10), fish eaters 0.96, low meat eaters 0.93. No significant difference in overall mortality.
Human2020
Vegetarian and vegan diets and risks of total and site-specific fractures: results from the prospective EPIC-Oxford study
BMC Medicine
54,898 participants, mean 17.6 years. Hip fracture adjusted for lifestyle and BMI against meat eaters: fish eaters HR 1.26, vegetarians 1.25, vegans 2.31 (1.66 to 3.22), equal to 14.9 more cases per 1,000 over ten years. No differences for wrist or ankle in any group.
Human2009
Type of vegetarian diet, body weight, and prevalence of type 2 diabetes
Diabetes Care
Cross-sectional prevalence, not incidence. 60,903 participants. Type 2 diabetes prevalence 2.9 percent in vegans against 7.6 percent in nonvegetarians, with adjusted odds ratio 0.51 for vegans even after adjusting for BMI.
Human2022
A Mediterranean diet and low-fat vegan diet to improve body weight and cardiometabolic risk factors: a randomized, cross-over trial
Journal of the American College of Nutrition
The only direct randomised comparison of these two patterns. 62 adults, crossover, 16 weeks per arm. Vegan won on weight (minus 6.0 kg against zero) and LDL; Mediterranean won on systolic blood pressure by 5.9 mmHg (p = 0.02); HOMA-IR not significant (p = 0.21).

What people report

These are uncontrolled self-reports, not evidence. They are here because they tell you what to expect and what to watch for, which the trial literature does not. They cannot tell you whether anything works.

Improved digestion and regularity, attributed to fibre, reported very consistently.
Increased food volume for the same calories, described as the main reason it feels sustainable.
Early bloating and gas as fibre intake rises, usually settling in two to four weeks.
Fatigue that resolves on addressing B12, iron or overall calorie intake, and often did not resolve because none of those was tested.
Difficulty reaching protein targets while training, the most common complaint from people combining this with lifting.
Strong social and ethical support structures, which shows up in the trial data as unusually good adherence.

Sources: r/vegan, r/PlantBasedDiet and r/veganfitness, plus the adherence data inside the trials, which is unusually good: 86 to 90 percent completion at 74 weeks in the Barnard diabetes trial. Uncontrolled self-report, useful for what to expect and for nothing else.

Who this is wrong for

Anyone who will not supplement B12. This is not a preference, it is the one nutrient that is absent from plant foods and where deficiency causes irreversible neurological damage.
Anyone who will not address calcium and vitamin D, given a hip fracture hazard ratio of 2.31 in vegans that the Adventist data suggests is confined to those not taking both.
Anyone with a history of haemorrhagic stroke or at high risk of one, until the EPIC-Oxford stroke finding is better understood. It did not attenuate on adjustment for disease risk factors and the mechanism is unestablished.
Anyone with iron-deficiency anaemia that is not being actively monitored, and children, where lower height and lower ferritin have been observed on a very low certainty evidence base.
Anyone trying to reach 1 gram of protein per pound of goal bodyweight without planning for it. It is achievable and it does not happen by default.

Questions

Does a vegan diet lower cholesterol?: Yes, and the evidence is unusually clean. In 22 pairs of identical twins, the vegan twin's LDL was 13.9 mg/dL lower than their own genetically identical co-twin after eight weeks. Because genetics and upbringing are controlled by the design, that finding is hard to explain any other way, though calories were not matched so part of it runs through a 1.9 kg weight difference.
Do vegans live longer?: The two large cohorts disagree, and this is the honest answer rather than a hedge. A North American Adventist cohort found 12 percent lower all-cause mortality for vegetarians overall, with the vegan estimate not reaching significance. A UK pooled analysis built around a comparable health-conscious meat-eating comparison group found no difference at all. Both are observational and neither settles it.
What about the stroke finding?: EPIC-Oxford found vegetarians had 20 percent higher total stroke over 18 years, driven by haemorrhagic stroke, about 3 more cases per 1,000 people over ten years. It is in the paper's published title and it is routinely omitted from summaries. Unlike the heart disease benefit in the same paper, it did not attenuate when disease risk factors were adjusted for. The mechanism is unestablished and a cohort cannot establish one.
Is the hip fracture risk real?: It is the largest adverse signal in this pattern: an adjusted hazard ratio of 2.31 in vegans, equal to 14.9 more hip fractures per 1,000 people over ten years. Adventist data indicates the excess is confined to those not taking both calcium and vitamin D, which makes it a solvable problem. Solving it means actually supplementing and testing, not assuming your diet covers it.
Can I build muscle on it?: Yes, and you have to plan the protein rather than expect it. Plant proteins run lower in leucine and lower on digestibility scores, so reaching a high target needs deliberate use of legumes, soy and isolated protein. The lean mass data inside these trials is too thin to quote, which is itself worth knowing.