Study: White bread, alcohol may increase risk for colorectal cancer

Key takeaways:

• White bread and alcohol had positive associations with CRC risk. In contrast, fiber and magnesium had inverse associations.
• More studies are needed to confirm the findings.

Consuming high amounts of white bread and alcohol were linked to an increased risk for colorectal cancer, a recent study in Nutrients showed. Meanwhile, fiber, magnesium and other dietary components were associated with a reduced risk.

Prior research has suggested that high bread intake may reduce the risk for cancer mortality and colorectal cancer (CRC) incidence. However, researchers said the study lacked data on white bread intake.

“We aimed to validate previous findings and to explore some new dietary factors associated with CRC risk to complement the shortcomings of previous studies due to their inclusion of fewer food groups,” Dongqing Jin, from the Zhejiang University School of Medicine in China, and colleagues wrote.

The researchers examined U.K. Biobank data on 118,210 participants (44% men; mean age, 55 years), using a polygenic risk score to determine correlations between CRC incidence and 139 food and dietary intakes.

Over a mean follow-up of 12.8 years, Jin and colleagues identified 1,466 CRC incidents. They observed positive associations between CRC risk and:

• alcohol (HR = 1.08; 95% CI, 1.03-1.14); and
• white bread (HR = 1.1; 95% CI, 1.05-1.16).

However, inverse associations were found for intakes of:

• dietary fiber (HR = 0.8; 95% CI, 0.69-0.93);
• calcium (HR = 0.8; 95% CI, 0.68-0.93);
• magnesium (HR = 0.82; 95% CI, 0.69-0.97);
• phosphorus (HR = 0.81; 95% CI, 0.68-0.97); and
• manganese (HR = 0.76; 95% CI, 0.65-0.88).

In particular, Jin and colleagues reported “significant protective effects” against CRC for dietary fiber (HR per one standard deviation increment in intake per day = 0.77; 95% CI, 0.67-0.88) and magnesium (HR per one standard deviation increment in intake per day = 0.74; 95% CI, 0.63-0.88).

According to the researchers, the effects of dietary fiber were consistent with findings from previous studies.

“Dietary fiber can accelerate intestinal motility, dilute carcinogens in the colon, and ferment fiber into short-chain fatty acids by gut bacteria, all mechanisms that suggest dietary fiber intake may reduce the risk of malignancy and improve colon health,” Jin and colleagues wrote. “In addition, dietary fiber can be used as a broad pillar of CRC prevention and adjuvant therapy.”

The study was limited due to its sample consisting entirely of European participants, according to the researchers. In addition, there was no mutual adjustment for dietary exposures.

Overall, the study “provides evidence and suggestions for dietary prevention of CRC,” although “more and larger cohort studies are needed in the future to validate our results and explore more associations between dietary components and CRC risk,” Jin and colleagues concluded.