March 12, 2015

Vegetarian diets linked to lower risk of colorectal cancers

Researchers at Loma Linda University Health have found that eating a vegetarian diet was associated with a lower risk of colorectal cancers compared with non-vegetarians in a study of Seventh-day Adventist men and women. The findings are described in an article published online by the Journal of the American Medical Association (JAMA) Internal Medicine. The study is part of Loma Linda University Health’s ongoing Adventist Health Study-2, which began in 2002.

Colorectal cancer is the second-leading cause of cancer death in the United States. The report notes that 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.

Among 77,659 study participants, lead author Michael J. Orlich, MD, PhD, and coauthors identified 380 cases of colon cancer and 110 cases of rectal cancer. Compared with non-vegetarians, vegetarians had a 22 percent lower risk for all colorectal cancers, 19 percent lower risk for colon cancer and 29 percent lower risk for rectal cancer. Compared with non-vegetarians, vegans had a 16 percent lower risk of colorectal cancer; lacto-ovo vegetarians (eat milk and eggs) had an 18 percent less risk; pesco-vegetarians (eat fish) had a 43 percent less risk; and semi-vegetarians (eat some meat) had an 8 percent less risk, according to the study results.

Study implications

This is the first report to come out of Loma Linda University Health’s ongoing Adventist Health Study-2 investigation that links diets to a specific form of cancer.

“If such associations are causal, they may be important for primary prevention of colorectal cancers,” Orlich says. “Prior studies have linked a vegetarian diet with the potential reduced risk of obesity, hypertension, diabetes and mortality.” 

Orlich adds, “The evidence in this online JAMA Internal Medicine article that vegetarian diets similar to those of our study participants may be associated with a reduced risk of colorectal cancer should also be considered carefully in making dietary choices and in giving dietary guidance.”

The Wall Street Journal covered these findings this week in this video.

NIH-funded study making a difference

The findings are part of Loma Linda University Health’s overarching Adventist Health Studies, which started in 1958 and is one of the world’s longest-running set of research studies on whole health, aging and longevity. This link provides more information on the studies:

CNN’s chief medical correspondent, Dr. Sanjay Gupta, recently cited Loma Linda University Health’s Adventist Health Studies on his “Vital Signs with Dr. Sanjay Gupta” show that focused on healthy aging and greater longevity. It aired in February on the CNN International channel and can be viewed online at The program is broken into three convenient clips: “The art of aging,” “The secrets of centenarians” and “The principles of living longer.”

Loma Linda University Health’s Adventist Health Study-2 started with funding from the National Cancer Institute (which is part of the National Institutes of Health). In 2011, the Adventist Health Study-2 was awarded a $5.5 million five-year grant from the National Cancer Institute to continue the study.

“We are climbing the stairway to greater knowledge and insights. This online JAMA Internal Medicine report takes us another step upward. More Adventist Health Study-2 reports will be published in the months ahead,” says Richard H. Hart, MD, DrPH, president of Loma Linda University Health. “The Loma Linda University Health team continues to research issues that aim to make a difference in people’s lives. We continue our commitment to lead people toward greater wholeness — an integrated health lifestyle that includes mind, body and spirit.”