Eating a vegetarian diet was associated with a lower risk of colorectal cancers compared with nonvegetarians according to a recent study of Seventh-Day Adventist men and women.
Findings from the study appear in an article published March 9 on the website of JAMA Internal Medicine.
Colorectal cancer is the second leading cause of cancer death in the U.S., according to the CDC. Although great attention has been paid to screening, primary prevention through lowering risk factors remains an important objective. Dietary factors have been identified as a modifiable risk factor for colorectal cancer, including red meat which is linked to increased risk and food rich in dietary fiber which is linked to reduced risk, according to the study background.
Data for the study came from the Adventist Health Study 2, which is a large, prospective cohort trial including Seventh-Day Adventist men and women enrolled between 2002 and 2007. Researchers assessed participants’ diets using a food frequency questionnaire at baseline.
Participants were categorized into four vegetarian dietary patterns — vegan, lacto-ovo vegetarian (eat milk and eggs), pescovegetarian (eat fish) and semivegetarian — and a nonvegetarian dietary pattern.
Among the 77,659 study participants, Michael J. Orlich, MD, PhD, of Loma Linda (Calif.) University and coauthors identified 380 cases of colon cancer and 110 cases of rectal cancer. Compared with nonvegetarians, vegetarians had a 22% lower risk for all colorectal cancers, 19% lower risk for colon cancer and 29% lower risk for rectal cancer, the findings showed. Compared with nonvegetarians, vegans had a 16% lower risk of colorectal cancer, 18% less for lacto-ovo vegetarians, 43% less in pescovegetarians and 8% less in semivegetarians, according to study results.
“If such associations are causal, they may be important for primary prevention of colorectal cancers,” the authors wrote. “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.”
The project was supported by grants from the National Cancer Institute and World Cancer Research Fund.