Vegetarian Diets Tied to Lower Risk for Some GI Cancers

Megan Brooks

September 29, 2023


Vegetarian diets may reduce the risk for gastric and colorectal cancers, according to the results of a meta-analysis.


  • Researchers did a systematic review and meta-analysis of seven original studies (six cohorts and one case-control) involving 686,691 people.

  • Pooled relative risk (RR) for gastric, colorectal, and upper gastrointestinal (GI) cancers were assessed with confidence intervals in multivariate analysis accounting for potential confounders.


  • Compared with nonvegetarian diets, vegetarian diets were inversely associated with the risk for GI tumor development (RR, 0.77).

  • In a subgroup analysis, vegetarian diets were negatively correlated with the risk for gastric cancer (RR, 0.41) and colorectal cancer (RR, 0.85) but not with upper GI cancer (excluding stomach; RR, 0.93).

  • Vegetarian diets were negatively correlated with the risk for GI cancer in men (RR, 0.57) but not women (RR, 0.89).

  • Vegetarian diets were negatively correlated with the risk for GI cancer in North American (RR, 0.76) and Asian populations (RR, 0.43) but not in European populations (RR, 0.83).


"The results of this systematic review indicate that adherence to vegetarian diets can reduce the risk of gastrointestinal cancers compared with non-vegetarian diets. This study provides a reference for primary prevention strategies for gastrointestinal cancers," the authors write.


The study, with first author Tongtong Bai, of Nanjing University of Chinese Medicine, Nanjing, China, was published online on September 18 in the European Journal of Gastroenterology & Hepatology.


The effects of vegetarian diets on GI tumorigenesis may be influenced by gender and geographical region. The heterogeneity of effects of vegetarian diets on different GI cancers could be due to the small number of studies included and could represent chance variation. The results need to be confirmed by studies of populations in other regions. There was evidence of publication bias.


The study had no specific funding. The authors have disclosed no conflicts of interest.

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