Need another reason not to subsist mostly on burgers, wings, and steaks? A new study suggests that men who eat a mostly plant-based diet have a lower risk of bowel cancer.
For the U.S. study, researchers examined the eating habits of 79,952 men. They found that men who consumed the most vegetables, whole grains, nuts, and legumes were 22 percent less likely to develop bowel cancer than their counterparts who rarely ate these foods.
But this was true only for men. Among the 93,475 women in the study, whether or not they followed a more plant-based diet didn’t appear to influence their bowel cancer risk, according to the study results, published November 29 in BMC Medicine.
And the protective effect of a plant-based diet was more pronounced for certain men. The cancer risk reduction associated with this type of diet was greater for people who identified as Japanese, Native Hawaiian, and white than for individuals who identified as Black or Latino.
“These findings emphasize the potential importance of the quality of plant foods on the prevention of colorectal cancer and suggest that the benefits from plant-based diets may vary by sex, race and ethnicity, and anatomic subsite of tumor,” wrote the senior study author, Song-Yi Park, PhD, of the cancer epidemiology program at University of Hawaii Cancer Center in Honolulu, and her colleagues.
To assess eating habits in the study, researchers asked participants how often they ate and drank 180 different types of foods and beverages and inquired about portion sizes. Researchers looked at a variety of food groups, including animal products like meat, dairy, eggs, fish, and seafood; healthier plant-based options like vegetables and legumes; and less healthy plant-based choices like french fries and heavily processed grains.
Over an average follow-up period of almost two decades, there were a total of 4,976 colorectal cancer cases among study participants.
While the study wasn’t designed to prove whether or how specific foods might directly cause cancer, it’s possible that people with healthier plant-based diets consumed more foods rich in fiber, antioxidants, and other nutrients associated with a lower cancer risk, the study team wrote. Conversely, it’s also possible that people who ate the most red and processed meats and refined grains consumed more sugars and fats that are associated with an increased risk of some cancers.
One limitation of the study was that researchers looked at all types of animal proteins as a single food group. This means they didn’t separate less-healthy options like red and processed meats from foods associated with a lower cancer risk like fish and dairy. Another drawback of the new study is that researchers lacked data on long-term eating habits to determine whether any changes over time might have influenced participants' cancer risk.
Colorectal cancer is the third most common type of cancer and the fourth main cause of cancer fatalities in the world, with about 1.8 million new cases and more than 881,000 deaths in 2018, a study published in the June 2019 International Journal of Cancer found.