1.8 million-person study finds mixed cancer links for vegetarian, pescatarian and vegan diets
Mar 2nd 2026
A pooled analysis of nine prospective studies with 1.8 million people shows some diet specific associations with cancer risk: pescatarian and vegetarian patterns linked to lower risks for several cancers while vegans and vegetarians showed higher risks for particular cancers, but most effects were small, inconsistent across sensitivity tests, and cannot establish causation.
- Analysis pooled 1.8 million people from nine prospective cohorts and recorded about 220,000 incident cancers.
- Pescatarians had a lower risk of colorectal cancer (hazard ratio 0.85) and lower risks for some other cancers.
- Vegans showed a higher colorectal cancer risk (HR 1.40) but the finding is based on small numbers and was not consistent across sensitivity checks.
- Vegetarians had a higher risk of squamous cell carcinoma of the oesophagus (HR 1.93) and a lower risk of kidney cancer (HR ~0.72), with the kidney finding robust in sensitivity analyses.
- Vegetarians and pescatarians had slightly lower postmenopausal breast cancer risk, much of which was reduced after accounting for body mass index.
- Many associations were modest or lost significance after excluding early follow up or in never smokers, and the study is observational so it cannot prove cause and effect.
- Most participants were from the UK and USA and vegans were few, so results may not generalize and could be affected by dietary misclassification or residual confounding.