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Vegetarians have lower bowel cancer risk than meat-eaters

Pesco-vegetarians have much lower relative risk of colorectal cancer even than vegans

Louise Prime

Tuesday, 10 March 2015

More evidence has emerged that colorectal cancer risk is lower in people who eat a vegetarian diet. Authors of the research*, published online in JAMA Internal Medicine, say their findings, along with those from earlier studies showing the benefits of vegetarianism in reducing the risks of obesity, hypertension and diabetes, should be take into account when offering dietary guidance.

In a cohort study funded jointly by the National Cancer Institute and the World Cancer Research Fund, the researchers compared the incidence of colon cancer and rectal cancer among 77,659 men and women in the US, all of them Seventh-Day Adventists, who had at baseline reported eating different types of diet. In this study population, there were 380 incident cases of colon cancer and 110 cases of rectal cancer over a mean of 7.3 years follow up.

They calculated that compared with non-vegetarians, people who were vegetarian had a 22% lower risk of all colorectal cancers – 19% lower for colon cancer and 29% lower for rectal cancer. Vegans had a 16% lower risk of colorectal cancer than non-vegetarians; lacto-ovo vegetarians (who eat milk products and eggs) had an 18% lower risk; pesco-vegetarians (who ate fish) had a 43% lower risk; and semi-vegetarians had an 8% lower risk. Estimates were similar for women and men, and for black and non-black people.

The study authors said: “Vegetarian diets are associated with an overall lower incidence of colorectal cancers. Pesco-vegetarians in particular have a much lower risk compared with non-vegetarians.” They suggested that, if the associations they found were causal, they may be important for primary prevention of colorectal cancers, which are the second leading cause of cancer death in the US.

They concluded: “The evidence that vegetarian diets similar to those of our study participants may be associated with a reduced risk of colorectal cancer, along with prior evidence of the potential reduced risk of obesity, hypertension, diabetes and mortality, should be considered carefully in making dietary choices and in giving dietary guidance.”

* Orlich MJ, et al. Vegetarian Dietary Patterns and the Risk of Colorectal Cancers. JAMA Intern Med. Published online March 09, 2015. doi:10.1001/jamainternmed.2015.59 http://dx.doi.org/10.1001/jamainternmed.2015.59

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