Research
Mixed
Vegetarian and vegan diets do not show clear differences in total mortality, stroke mortality, or cancer rates (colorectal, breast, prostate) compared to non-vegetarians, although IHD mortality is lower.
Switching to a vegetarian diet improves heart health but does not necessarily extend your total lifespan compared to a healthy omnivorous diet. Focus on the specific benefits for heart health and weight management rather than expecting a dramatic increase in overall longevity.
GoodRefutesHIGH confidence
Cohort studies of vegetarians have shown a moderate reduction in mortality from IHD but little difference in other major causes of death or all-cause mortality in comparison with health-conscious non-vegetarians from the same population. Studies of cancer have not shown clear differences in cancer rates between vegetarians and non-vegetarians.
Why this rating
Based on large collaborative analyses of prospective studies and EPIC-Oxford.
Source
Health effects of vegetarian and vegan diets
Timothy J. Key et al. · Proceedings of The Nutrition Society · 2006
DOI 10.1079/pns2005481
narrative_reviewCited 406×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
More from this paper
- Adopting a vegetarian or vegan diet is associated with a moderate reduction in mortality from ischemic heart disease (IHD) compared to non-vegetarian diets, primarily driven by lower plasma cholesterol levels and lower body mass index (BMI).Good
- Vegetarian and vegan diets are consistently associated with a lower Body Mass Index (BMI) and slower weight gain over time compared to non-vegetarian diets, although obesity prevalence can still be high in specific subgroups.Good
- Vegetarian and vegan diets are associated with suboptimal Vitamin B12 status and elevated homocysteine levels, requiring careful monitoring and supplementation to avoid potential health risks.Good
Related findings · Mixed
- Bariatric surgery (VSG and RYGB) is the most effective and sustainable treatment for obesity, producing marked and sustained weight loss that non-surgical interventions cannot match.Strong
- Severely protein-deficient diets (2–3% energy) induce lean body mass loss and metabolic imbalance, whereas adequate protein intake (0.66 g/kg/d minimum) is a prerequisite for maintaining muscle, bone, and physiological function.Strong
- For patients with Class III obesity (BMI >39.9 kg/m2), metabolic bariatric surgery (MBS) is significantly more effective than any currently approved medication, with BilioPancreatic Diversion (BPD) showing the highest estimated weight loss.Strong
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