New Delhi: A large international study has found that low dietary fibre intake is closely linked to changes in the gut microbiome associated with colorectal cancer, adding to growing evidence that diet plays a crucial role in preventing one of the world’s most common cancers.
The findings, published in the journal Cell Host & Microbe, show that increasing fibre intake may help reduce the presence of gut microbes linked to colorectal cancer, potentially lowering disease risk.
Researchers from the European Molecular Biology Laboratory (EMBL) and collaborating institutions re-analysed data from 27 previously published studies, examining 6,779 publicly available gut microbiome profiles. They also analysed 906 intestinal tissue samples to compare microbial communities found in stool with those present directly in tumour tissue.
The team identified a robust microbial signature consistently associated with colorectal cancer across different populations, geographic regions, sequencing technologies and age groups. The signature was found in both early-onset and late-onset colorectal cancer, suggesting it is a common feature of the disease rather than being limited to specific patient groups.
Importantly, researchers observed a significant inverse relationship between dietary fibre intake and the colorectal cancer microbiome score. Individuals consuming more fibre had lower levels of cancer-associated microbial patterns, while dietary interventions aimed at increasing fibre intake reduced these scores in both cancer patients and healthy participants.
“The strength of this study is its comprehensiveness,” lead author Georg Zeller of EMBL Heidelberg and Leiden University Medical Center said. By combining stool and tissue analyses with dietary information and bacterial strain-level analysis, the researchers were able to identify microbial patterns that remained consistent across multiple datasets.
The study also found that cancer-associated microbes were detectable in early-stage tumour tissue. However, stool-based detection was less accurate in patients with early-stage disease or tumours located deeper within the colon, indicating that further improvements are needed before microbiome-based screening can be widely adopted.
Scientists believe dietary fibre nourishes beneficial gut bacteria that produce short-chain fatty acids, compounds known to reduce inflammation, strengthen the intestinal lining and support overall colon health. A lack of fibre may disrupt this balance, allowing potentially harmful microbes to flourish. Previous research has similarly linked higher fibre intake with healthier gut microbiota and a lower risk of colorectal cancer.
Researchers said their machine-learning approach can be applied to existing microbiome datasets, helping scientists better understand how lifestyle and dietary factors influence gut microbial communities and disease risk. They added that the findings highlight the value of combining large-scale public datasets to uncover reliable biological patterns that may have been missed in smaller individual studies.
The researchers cautioned that while the study demonstrates a strong association between dietary fibre, gut microbes and colorectal cancer, it does not prove that low fibre intake directly causes the disease. However, they said the findings reinforce existing public health advice encouraging diets rich in fruits, vegetables, legumes and whole grains to support gut health and reduce colorectal cancer risk.
