Diets
plant-based diet decreases cancer risk including colorectal
In plain terms: Do vegetarians get less cancer, especially gut cancers?
Part of: 🥗 plant-based diet
Modestly — large cohorts show a small reduction in overall and digestive/colorectal cancer incidence, but associations are weak, confounded, and null for several sites.
Evidence ladder
How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."
Top evidence so far: All trials, pooled (Meta-analysis)
How the studies fall
The evidence (12)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Fraser 2025 · Am J Clin Nutr | observational | mixed | moderate | In AHS-2, vegetarian diets linked to lower risk of several site-specific cancers but not uniformly across sites. |
| Parra-Soto 2022 · BMC Med | observational | mixed | moderate | UK Biobank + meta-analysis: vegetarian/low-meat diets modestly lower overall and some site-specific cancer risk, not all sites. |
| Xie 2025 · J Gastrointest Surg | meta-analysis | supports | moderate | Plant-based dietary patterns inversely associated with colorectal cancer risk, quality-dependent. |
| Dinu 2017 · Crit Rev Food Sci Nutr | observational | supports | moderate | Meta-analysis of observational studies: vegetarian/vegan diets associated with ~8-15% lower overall cancer incidence. |
| Orlich 2015 · JAMA Intern Med | observational | supports | high | Vegetarian dietary patterns associated with lower colorectal cancer incidence (HR 0.78) in AHS-2. |
| Zhao 2022 · Front Public Health | meta-analysis | supports | moderate | Meta-analysis (over 3M subjects): plant-based dietary patterns associated with lower risk of digestive-system (incl. colorectal) cancers. |
| Huang 2012 · Ann Nutr Metab | meta-analysis | supports | moderate | Vegetarians had ~18% lower overall cancer incidence than nonvegetarians in pooled cohorts. |
| Godos 2017 · J Hum Nutr Diet | meta-analysis | mixed | moderate | Vegetarian diets associated with lower colorectal cancer risk but no significant effect on breast or prostate cancer. |
| Gil-Lespinard 2026 · Eur J Nutr | meta-analysis | supports | high | Healthful plant-based diet indices associated with lower breast, colorectal and liver cancer risk in pooled cohorts. |
| Dunneram 2026 · Br J Cancer | observational | mixed | moderate | Pooled analysis of 1.8M people across 9 cohorts: vegetarian diets associated with modestly lower risk of some cancers but not consistently across all sites. |
| Ginter 2008 · Bratisl Lek Listy | observational | tested-null | low | Review citing meta-analyses with no significant vegetarian-vs-health-conscious-omnivore difference in colorectal, stomach, lung, prostate or breast cancer mortality. |
| Bai 2023 · Eur J Gastroenterol Hepatol | meta-analysis | supports | moderate | Vegetarian diets associated with 23% lower gastrointestinal cancer risk, strongest for gastric and colorectal. |
Disagree, or know a study we missed?
We grade by evidence, not opinions. The way to weigh in is to point us to a study we haven't cited (check the evidence table above first), or to flag a problem with one we have. Every submission is reviewed; if it holds up, the grade updates and shows in Science Changes Its Mind.
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Educational only, not medical advice. Grades and scores reflect published evidence weighted by study design and quality; see the methodology.