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.
📅 Last reviewed: 2026-07-15 ⓘ
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
What the evidence shows
Large cohorts show plant-based and vegetarian diets associated with modestly lower overall cancer incidence, around 8 to 15 percent, and lower colorectal cancer specifically, at a hazard ratio near 0.78 in Adventist Health Study-2. The associations are weak, not uniform across cancer sites, and observational throughout, so confounding by the rest of a vegetarian lifestyle is unresolved.
The evidence (12)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Fraser GE, Butler FM, Shavlik DJ, Mathew RO, Oh J, Sirirat R, Abramov D, Sveen LE 2025 · Am J Clin Nutr | observational | supports | moderate | In AHS-2, vegetarian diets linked to lower risk of several site-specific cancers but not uniformly across sites. |
| Parra-Soto S, Ahumada D, Petermann-Rocha F, Boonpoor J, Gallegos JL, Anderson J, Sharp L, Malcomson FC, Livingstone KM, Mathers JC, Pell JP, Ho FK, Celis-Morales C 2022 · BMC Med | observational | supports | moderate | UK Biobank + meta-analysis: vegetarian/low-meat diets modestly lower overall and some site-specific cancer risk, not all sites. |
| Xie L, Li Y, Song Z, Huang Y, Yao Q 2025 · J Gastrointest Surg | meta-analysis | supports | moderate | Plant-based dietary patterns inversely associated with colorectal cancer risk, quality-dependent. |
| Dinu M, Abbate R, Gensini GF, Casini A, Sofi F 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 MJ, Singh PN, Sabaté J, Fan J, Sveen L, Bennett H, Knutsen SF, Beeson WL, Jaceldo-Siegl K, Butler TL, Herring RP, Fraser GE 2015 · JAMA Intern Med | observational | supports | high | Vegetarian dietary patterns associated with lower colorectal cancer incidence (HR 0.78) in AHS-2. |
| Zhao Y, Zhan J, Wang Y, Wang D 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 T, Yang B, Zheng J, Li G, Wahlqvist ML, Li D 2012 · Ann Nutr Metab | meta-analysis | supports | moderate | Vegetarians had ~18% lower overall cancer incidence than nonvegetarians in pooled cohorts. |
| Godos J, Bella F, Sciacca S, Galvano F, Grosso G 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 M, Iglesias-Vázquez L, Jakszyn P 2026 · Eur J Nutr | meta-analysis | supports | moderate | Healthful plant-based diet indices associated with lower breast, colorectal and liver cancer risk in pooled cohorts. |
| Dunneram Y, Lee JY, Watling CZ, Lawson I, Parsaeian M, Fraser GE, Butler FM, Prabhakaran D, Shridhar K, Kondal D, Mohan V, Ali MK, Narayan KMV, Tandon N, Tong TYN, Travis RC, Chiu THT, Lin MN, Lin CL, Yang HC, Liang YJ, Greenwood DC, Reeves GK, Papier K, Floud S, Sinha R, Liao LM, Loftfield E, Cade JE, Key TJ, Perez-Cornago A 2026 · Br J Cancer | observational | mixed | high | 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 E 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 T, Peng J, Zhu X, Wu C 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?
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Educational only, not medical advice. Grades and scores reflect published evidence weighted by study design and quality; see the methodology.