The risk of colorectal cancer is reduced by consuming a healthy plant-based diet, according to a study published in the journal BMC Medicine conducted in a multiethnic population.^1,2

The association between plant-based diet and the risk of colorectal cancer was investigated in 79,952 men and 93,475 women, aged 45-75 years, from the Multiethnic Cohort Study. The follow up period was 19.2 years (average). Information about diet was self-reported through a questionnaire. Three plant-based diet scores - the overall plant-based diet index (PDI), healthful plant-based diet index (hPDI) and unhealthful plant-based diet index (uPDI) were calculated. Healthy plant-based foods included whole grains, fruits, vegetables, vegetable oils, nuts, legumes, tea, and coffee, whereas refined grains, fruit juices, potatoes and added sugars were included as unhealthy plant-based foods.

A total of 4976 new cases of colorectal cancers were detected over the course of the study. Eating a healthy-plant based diet lowered the risk of colorectal cancer in men but not in women. This association with overall plant-based diet index was found to be more significant among the Japanese American, Native Hawaiian and White population vis a vis the other groups, where the reduction in risk with a healthy plant-based diet index was consistent across all participants. This association was also more robust for rectal and left colon tumors than for right sided tumors. Expectedly, no beneficial effect of an unhealthy plant-based diet was observed.

This study emphasizes the impact of lifestyle on the risk of cancer. The beneficial effects of a healthy plant-based diet in this study differed by ethnicity, sex and the anatomic location of the tumor. The American Cancer Society also recommends eating a diet rich in fruits and vegetables and whole grains to reduce the risk of colorectal cancer.

References

1. Kim J, et al. Plant-based dietary patterns defined by a priori indices and colorectal cancer risk by sex and race/ethnicity: the Multiethnic Cohort Study. BMC Med. 2022 Nov 29;20(1):430. doi: 10.1186/s12916-022-02623-7.
2. Katharine Lang. https://www.medicalnewstoday.com/articles/new-evidence-links-healthy-plant-based-diets-with-lower-colorectal-cancer-risk, dated Nov. 30, 2022. Accessed Dec. 3, 2022.