Do Lifestyles Directly Influence the Composition of the Gut Microbiota and the Risk of Colorectal Cancer?

Colorectal cancer is among the most common and deadliest cancers worldwide. Its incidence continues to rise, particularly among young adults. While diet, sedentary lifestyle, and overweight are recognized as major risk factors, the biological mechanisms linking these lifestyle habits to the onset of the disease remain poorly understood. A promising avenue lies in the role of the gut microbiota, the community of microorganisms that inhabit our digestive system and whose balance appears closely linked to our health.

A recent analysis conducted on over 1,200 Finnish adults reveals that lifestyles associated with a high risk of colorectal cancer are accompanied by specific changes in the gut microbiota. Researchers evaluated nine key factors, such as body mass index, red meat consumption, physical activity, and alcohol consumption. They observed that individuals with less favorable habits exhibited reduced microbial diversity. This decline in diversity is often associated with an imbalance that may promote inflammation and carcinogenesis.

The study also shows that certain groups of bacteria, such as those from the Lachnospiraceae family, are more abundant in high-risk individuals. Conversely, beneficial bacteria like Bifidobacterium, known for producing protective compounds such as short-chain fatty acids, are less prevalent. These fatty acids play an important role in regulating inflammation and may help prevent the early stages of tumor formation.

Lachnospiraceae, particularly the genera Dorea and Mediterraneibacter, have already been linked to early stages of colorectal cancer in other research. Their proliferation may reflect a less healthy gut environment, promoted by a diet rich in processed meats, excess weight, or lack of exercise. In contrast, Bifidobacterium, often stimulated by a fiber-rich diet, appear to play a protective role.

These findings suggest that daily choices regarding diet and physical activity not only affect our weight or metabolism but also directly influence the composition of our microbiota. Over time, these changes could create an environment more conducive to the development of colorectal cancer. Understanding these interactions paves the way for more targeted prevention strategies, aiming to restore a favorable microbial balance from the early years of adulthood.

The study also confirms that the combined effect of multiple risk factors amplifies microbiota disruptions far more than each factor taken in isolation. For example, the combination of high alcohol consumption and overweight appears to worsen microbial imbalances, thereby increasing the risk of cancer beyond the simple sum of individual effects.

While these observations do not yet establish a direct causal link, they reinforce the idea that the gut microbiota acts as an intermediary between our lifestyle habits and our digestive health. They also highlight the importance of a holistic approach, integrating diet, physical activity, and weight management, to maintain a diverse microbiota and reduce long-term risks. These discoveries could inspire future recommendations aimed at optimizing the composition of the microbiota from the earliest stages of prevention.

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Official Study Source

DOI: https://doi.org/10.1007/s10552-026-02144-1

Title: Interplay between colorectal cancer-related lifestyles and the gut microbiome: an exploratory analysis of metagenomic data

Journal: Cancer Causes & Control

Publisher: Springer Science and Business Media LLC

Authors: Rilla Tammi; Mirkka Maukonen; Niina E. Kaartinen; Kari Koponen; Teemu Niiranen; Guillaume Méric; Demetrius Albanes; Johan G. Eriksson; Pekka Jousilahti; Seppo Koskinen; Anne-Maria Pajari; Rob Knight; Aki S. Havulinna; Veikko Salomaa; Satu Männistö