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Researcher: Caroline Um, PhD, MPH, RD
Institution: American Cancer Society
Area of Focus: Population Science
“In a previous ACS study that used data from the full 1.2 million men and women in the CPS-II cohort, we found that coffee drinkers who didn’t smoke had a lower risk of death from colorectal cancer, and their risk was slightly lower if they drank decaffeinated coffee.
“To explore further, in this study we looked at coffee drinkers who developed colorectal cancer in the CPS-II Nutrition cohort. We found that only those who drank decaffeinated coffee had a lower risk of colorectal cancer, regardless of their smoking status.
"Next, we’ll examine stool samples from CPS-3 participants in the Gut Microbiome Sub-study to learn more about the relationship between caffeinated and decaffeinated coffee with the gut microbiome.”
The Challenge: Many people around the world drink coffee, and the number keeps rising. Experimental studies suggest that coffee and caffeine may potentially help protect against the development of colorectal cancer, but observational studies have not shown a beneficial relationship.
The Research: Caroline Um, PhD, MPH, RD, and her colleagues at the American Cancer Society (ACS) examined the link between drinking caffeinated or decaffeinated coffee and the risk of colorectal cancer among more than 107,000 participants, ages 47 to 96, in the CPS-II Nutrition Cohort. These male and female participants answered surveys about what they ate and drank in 1999 and 2003. By 2015, 1,829 cases of colorectal cancer were verified.
As reported in Cancer Epidemiology, Um and her colleagues found that people who drank 2 or more cups of decaffeinated coffee a day had a lower risk of colon and rectal cancer, compared to people who didn’t drink decaffeinated coffee. In comparison, people who drank 2 or more cups of caffeinated coffee had a higher risk of rectal cancer, but not of colon cancer.
Why Does It Matter? Although these results need to be replicated in a future study, the findings suggest that there may be different associations between colorectal cancer risk and drinking caffeinated or decaffeinated coffee. For instance, differences in risk may be related to how the body metabolizes different types of coffee, including potential metabolism by gut microbiota. Plus, associations may vary by the area where cancer develops in the colon or rectum.
Improving our understanding of the relationship between different foods and beverages, including coffee, and colorectal cancer risk can help inform dietary guidelines and recommendations to lower cancer risk.