Death from any cause

All-cause mortality is the bluntest measure in nutrition research and the one most often quoted. It has a real advantage: nobody has to decide which disease to count. It has a real weakness: it mixes everything together, and a diet that changes one cause of death while worsening another can look like nothing at all.

In the Adventist Health Study 2, with 2,570 deaths among 73,308 participants over a mean 5.79 years, all vegetarians combined had a hazard ratio for all-cause mortality of 0.88 (95% confidence interval 0.80 to 0.97) against non-vegetarians, and vegans alone 0.85 (0.73 to 1.01) — an interval that includes 1.00. [1] [1]

The same study reports that associations in men were larger and more often significant than in women, and that the cohort is a North American religious population. [1] [1]

The largest cohort analysis of protein source and mortality looked at what replaced what, which is the question the dietary advice actually turns on.

Among 131,342 United States health professionals, animal protein intake was not associated with all-cause mortality (hazard ratio 1.02 per 10% of energy, 95% confidence interval 0.98 to 1.05) but was associated with higher cardiovascular mortality (1.08, 1.01 to 1.16), while plant protein was associated with lower all-cause mortality (0.90 per 3% of energy, 0.86 to 0.95). [2] [2]

In that study the associations appeared only in participants with at least one unhealthy lifestyle factor — smoking, heavy alcohol intake, overweight or obesity, or physical inactivity — and were not evident among those with none of them. [2]

In the same cohorts, substituting 3% of energy from plant protein for the same energy from processed red meat was associated with a hazard ratio for all-cause mortality of 0.66 (95% confidence interval 0.59 to 0.75), from unprocessed red meat 0.88 (0.84 to 0.92), and from egg 0.81 (0.75 to 0.88). [2]

Pooling the cohorts gives a smaller and more stable number than any single study, and it comes with its own warning attached.

A meta-analysis of 32 prospective cohort studies, with 113,039 deaths among 715,128 participants, found plant protein intake was associated with a lower risk of all-cause mortality (pooled effect size 0.92, 95% confidence interval 0.87 to 0.97) and cardiovascular mortality (0.88, 0.80 to 0.96), with an additional 3% of energy a day from plant protein associated with a 5% lower risk of death, but heterogeneity was high (I² = 57.5%). [3] [3]

Two findings outside the plant-versus-animal frame are among the few in this entry that would survive a strict reading of the evidence. Both are about carbohydrate quality and both are graded, by their own authors, above the usual standard.

A series of systematic reviews covering just under 135 million person-years, 185 prospective studies and 58 clinical trials found that the highest fibre consumers had 15% to 30% lower all-cause and cardiovascular mortality than the lowest, with the greatest risk reduction between 25 and 29 grams of fibre a day, and the certainty of the evidence graded moderate for fibre. [4] [4] [4]

A meta-analysis of 12 major food groups found that each additional daily serving of whole grains was associated with a relative risk of all-cause mortality of 0.92 (95% confidence interval 0.89 to 0.95), of vegetables 0.96 (0.95 to 0.98), of fruits 0.94 (0.92 to 0.97), of nuts 0.76 (0.69 to 0.84) and of fish 0.93 (0.88 to 0.98), while red meat was 1.10 (1.04 to 1.18) and processed meat 1.23 (1.12 to 1.36). [5]

The same meta-analysis reports that its estimate of the risk reduction from optimal intakes of risk-decreasing foods is a 56% reduction in all-cause mortality, and describes the consumption of risk-increasing foods as associated with a two-fold increased risk. [5]

Now the counter-signal, because a page that reported only the rows above would be doing the thing this project exists to avoid. A panel was convened specifically to ask whether the red-meat evidence supports the advice built on it. It read the same body of work and reached a different recommendation.

A panel convened to write dietary guideline recommendations concluded that adults may continue their current unprocessed red meat and processed meat consumption, as weak recommendations based on low-certainty evidence, and stated that considerations of environmental impact or animal welfare did not bear on them. [6] [6]

The systematic review behind those recommendations, covering 61 articles on 55 cohorts with more than 4 million participants, found low-certainty evidence that reducing unprocessed red meat by three servings a week is associated with a very small reduction in risk for cardiovascular mortality, stroke, myocardial infarction and type 2 diabetes, and named inadequate adjustment for known confounders and recall bias among its limitations. [7] [7]

The same review concludes that the magnitude of association between red and processed meat consumption and all-cause mortality and adverse cardiometabolic outcomes is very small, and the evidence of low certainty. [7]

Those two positions cannot both be the whole story, and the difference between them is how much weight to give to a small association measured in observational data. The page keeps both because the disagreement is the finding.

What this section does not show

A blunt measure

All-cause mortality mixes every cause together, so a diet that improves one and worsens another can look like nothing at all. This section names that limit where it matters.

The intervals are the finding

The vegan interval in the Adventist cohort includes 1.00, which is why it is printed rather than rounded off. An interval that crosses 1.00 is a different sentence from a benefit.

The evidence is disputed by people who read it

A guideline panel read the same red-meat studies and recommended no change, on low-certainty evidence. This section carries that recommendation beside the results it cuts against.

Nothing here predicts a life

No source in this entry establishes that any diet extends lifespan, and none of these numbers predicts how long any person will live.

All twelve elements

The entry's full limits block covers the dates, the study designs, who was and was not studied, the comparators, the adjustment sets, the uncertainty, the counter-signals and what we did not check. Read it on the entry's first page.

This page is general information about published research. It is not medical advice, and it is not a substitute for advice from a qualified health professional. No clinician-patient relationship exists, and we do not know your diet, your medications, your test results, your medical conditions or your history. Talk to a health professional before changing your diet if you are pregnant or breastfeeding, feeding an infant or child, over 65, taking medication, living with a medical condition, or if you have been diagnosed with a nutrient deficiency or have a history of disordered eating. The evidence described is about groups and diets, not about you, and not about any product listed on this site. If you are unwell, contact a health professional; in an emergency, call 911. No clinician reviewed this entry. It is a compilation of published sources by this site.

Sources for this section

Every numbered sentence above was checked against the source with that number on the date shown. The number links to the entry in this list, and the entry's first page lists every source it cites.

1. Vegetarian dietary patterns and mortality in Adventist Health Study 2. JAMA Internal Medicine. prospective cohort study. Open the source ↗
   Checked 19 September 2026. Backs 2 sentences in this section.
2. Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality. JAMA Internal Medicine. prospective cohort study. Open the source ↗
   Checked 19 September 2026. Backs 3 sentences in this section.
3. Dietary intake of total, animal, and plant proteins and risk of all cause, cardiovascular, and cancer mortality: systematic review and dose-response meta-analysis of prospective cohort studies. The BMJ. systematic review and meta-analysis. Open the source ↗
   Checked 19 September 2026. Backs 1 sentence in this section.
4. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. The Lancet. systematic review and meta-analysis. Open the source ↗
   Checked 19 September 2026. Backs 1 sentence in this section.
5. Food groups and risk of all-cause mortality: a systematic review and meta-analysis of prospective studies. The American Journal of Clinical Nutrition. systematic review and meta-analysis. Open the source ↗
   Checked 19 September 2026. Backs 2 sentences in this section.
6. Unprocessed Red Meat and Processed Meat Consumption: Dietary Guideline Recommendations From the Nutritional Recommendations (NutriRECS) Consortium. Annals of Internal Medicine. guideline recommendations. Open the source ↗
   Checked 19 September 2026. Backs 1 sentence in this section.
7. Red and Processed Meat Consumption and Risk for All-Cause Mortality and Cardiometabolic Outcomes: A Systematic Review and Meta-analysis of Cohort Studies. Annals of Internal Medicine. systematic review and meta-analysis. Open the source ↗
   Checked 19 September 2026. Backs 2 sentences in this section.