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The Evidence

Page 15

Plant-based diets and longevity

One large cohort found vegetarians die at lower rates; another found no difference. The honest answer on longevity is that the evidence is split.

Vegan Brief Evidence last reviewed July 9, 2026

This is a summary of the cited evidence, not medical advice.

  • US cohort (AHS-2) 12% lower, HR 0.88
  • UK cohort (EPIC-Oxford) No difference
  • Verdict Genuinely split

The short version

Do vegetarians live longer? The two largest studies to ask disagree, and the honest answer sits in that gap. Adventist Health Study-2, tracking more than 73,000 Americans, found lower death rates for vegetarians.

Primary source 01 / 04

The adjusted hazard ratio (HR) for all-cause mortality in all vegetarians combined vs non-vegetarians was 0.88 (95% CI, 0.80-0.97).

Orlich and colleagues Loma Linda University Adventist Health Study 2, JAMA Internal Medicine, 2013

A hazard ratio of 0.88 means about 12% lower risk of dying during follow-up, and the confidence interval stays below 1.0, so the result is statistically real within this cohort. The authors stated it without inflating it.

Primary source 02 / 04

Vegetarian diets are associated with lower all-cause mortality and with some reductions in cause-specific mortality. Results appeared to be more robust in males.

Orlich and colleagues Loma Linda University Adventist Health Study 2, JAMA Internal Medicine, 2013

The other big cohort found no difference

Then the counterweight. A pooled analysis of more than 60,000 people in the United Kingdom, from the Oxford cohorts, looked for the same longevity advantage and did not find one.

Primary source 03 / 04

There was no significant difference in overall (all-cause) mortality between the diet groups

Appleby and colleagues University of Oxford EPIC-Oxford and Oxford Vegetarian Study, American Journal of Clinical Nutrition, 2016

Primary source 04 / 04

United Kingdom-based vegetarians and comparable nonvegetarians have similar all-cause mortality. Differences found for specific causes of death merit further investigation.

Appleby and colleagues University of Oxford EPIC-Oxford and Oxford Vegetarian Study, American Journal of Clinical Nutrition, 2016

Why they disagree

The gap is not a mystery. The two studies compared vegetarians against different yardsticks. In the UK cohorts, even the meat eaters were health-conscious volunteers, so the comparison group was already low-risk and the diet had less room to show a difference. The Adventist authors flagged this split themselves, noting that the UK cohort did not show an all-cause mortality advantage while their own did.

Both studies are observational, so neither proves cause. The fair reading is that the evidence for a longevity benefit is mixed for all-cause mortality and clearer for specific causes such as heart disease. Anyone selling plant-based eating as a guaranteed longer life is ahead of the data; anyone dismissing it has to explain away the Adventist result. Mixed is the accurate grade.

  • Plant-based diets and heart disease The heart-disease evidence is genuinely good for plant-based eating, and honest reporting includes the one finding that cut the other way: stroke.
  • Plant-based diets and type 2 diabetes Vegetarians and vegans get type 2 diabetes far less often, and a vegan diet helps manage it, though the trial effect on blood sugar is real and modest, not a cure.
  • Plant-based diets and blood pressure Plant-based eating lowers blood pressure by a few millimetres of mercury, small for one person but the kind of shift that moves population risk.
  • Plant-based diets and cancer risk Going plant-based nudges cancer risk down, mostly through what you stop eating. The overall effect is real, modest, and easy to oversell in either direction.

Frequently asked

Do vegans and vegetarians live longer?

It depends which study you read. Adventist Health Study-2 found 12% lower all-cause mortality in vegetarians (hazard ratio 0.88), but a large UK pooled analysis found no significant difference in all-cause mortality. Both are observational, so neither proves cause.

Why do the studies disagree on longevity?

Mostly because of the comparison group. In the UK cohorts the meat eaters were also health-conscious volunteers, leaving little room for a difference, while the US Adventist comparison group was less so. The evidence is clearer for specific causes like heart disease than for overall mortality.

The primary sources

The documents this page quotes. Read them yourself.

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