Story at a glance
- Previous research has found an association between foods rich in dietary fiber and a decreased risk of colorectal cancer.
- The latest findings include data from more than 170,000 American adults, recruited to the Multiethnic Cohort Study.
- Risk of colorectal cancer varied among men based on race and ethnicity.
Eating a healthy, plant-based diet was associated with a 22 percent lower risk of colorectal cancer among American men, new study results show. However, no association between dietary intake of healthy plant foods and the cancer risk was seen among women.
Findings are based on a study of more than 170,000 American individuals and were published in the journal BMC Medicine.
“Colorectal cancer is the third most common cancer worldwide and the risk of developing colorectal cancer over a lifetime is one in 23 for men and one in 25 for women,” said study author Jihye Kim of Kyung Hee University in South Korea, in a statement.
“Although previous research has suggested that plant-based diets may play a role in preventing colorectal cancer, the impact of plant foods’ nutritional quality on this association has been unclear.”
Researchers assessed dietary intake of healthy plant foods like whole grains, vegetables and legumes and unhealthy plant foods including refined grains, fruit juices and added sugars. They then compared those who ate the highest average daily amounts of plant-based food and those who ate the lowest amounts.
All individuals were recruited from Hawaii and Los Angeles to participate in the study between 1993 and 1996. At the start of the study, the average male age was 60 and average female age was 59. Using cancer registries, researchers calculated the incidence of colorectal cancer cases until 2017. A total of 4,976 participants developed cancer throughout the study window.
Antioxidants found in fruits, vegetables and whole grains could suppress chronic inflammation, which leads to cancer, authors hypothesized.
“As men tend to have a higher risk of colorectal cancer than women, we propose that this could help explain why eating greater amounts of healthy plant-based foods was associated with reduced colorectal cancer risk in men but not women,” Kim added.
However, risks of developing the cancer varied by race and ethnicity. Japanese American men who ate the highest amount of healthy plant foods per day had a 20 percent lower risk than those who ate the lowest amount. Among white men, risk was lowered by 24 percent. Overall, the inverse association was greater in Japanese American and white men than African American, Native Hawaiian and Latino groups.
Different colorectal cancer risk factors may have influenced the differences between racial and ethnic groups, but research is needed to confirm this, authors concluded.