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How Caff and Decaf Coffee Affect the Risk for Colorectal Cancer

CPS-II Nutrition Cohort Study shows people who drink decaffeinated coffee have a lower risk of colorectal cancer, regardless of their smoking status.

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

In a previous American Cancer Society (ACS) study, Caroline Um, PhD, MPH, RD, and her Population Science colleagues used data from the full 1.2 million men and women in the CPS-II Nutrition Cohort to examine the link between drinking caffeinated or decaffeinated coffee. "We found that coffee drinkers who didn’t smoke had a lower risk of death from colorectal cancer," Um says. "And their risk was slightly lower if they drank decaffeinated coffee," she adds. 

In a more current study, the team limited their study group to CPS-II Nutrition cohort participants who were coffee drinkers and who developed colorectal cancer. As reported in Cancer Epidemiology, Um and 

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.”

Caroline Um, PhD, MPH, RD

Principal Scientist, Population Science

American Cancer Society

close up portrait of Caroline Um

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.