New gut microbiome study connect obesity with certain types of cancer

A new review pulls together research suggesting that the gut microbiome, the community of microbes living in the intestines, links obesity and colorectal cancer. That connection now looks central rather than a side note.

In the United States, about 40 percent of adults now meet criteria for obesity, according to a national survey.

Colorectal cancer is also a leading cause of cancer death, so linking these conditions through gut microbes could reshape prevention efforts.

Linking obesity and cancer

The work was led by Hashim Muhammad Moseeb, a medical researcher at the University of Missouri. His research focuses on how changes in gut bacteria influence obesity, cancer, and other metabolic diseases.

“The gut microbiome functions as both a biomarker and therapeutic target across metabolic and neoplastic diseases,” said Moseeb.

In this context a biomarker, a measurable signal in the body that tracks disease risk, turns gut microbes into both clues and levers for health.

Because gut microbes respond quickly to diet and medications, they can also be changed more easily than human genes.

That makes them an appealing focus for strategies that aim to prevent disease rather than only treating it after it appears.

How gut microbes drive obesity

Many adults living with obesity also develop metabolic syndrome, a group of risk factors tied to heart disease.

The review highlights that people with this pattern often show lower microbial diversity and more bacteria that drive inflammation in fat tissue.

In one large European study, people with fewer gut microbial genes tended to have more body fat, insulin resistance, and signs of chronic inflammation.

This finding supports the idea that a thinner, less varied microbial community can go hand in hand with higher metabolic risk.

Certain gut bacteria break down dietary fiber into short chain fatty acids, small molecules that feed colon cells and calm inflammation.

Recent research shows that these molecules strengthen the gut barrier and quiet some of the immune signals that drive chronic inflammation.

When the balance of microbes skews toward species that leak inflammatory molecules into the bloodstream, fat tissue becomes less responsive to insulin. 

This pattern, often called dysbiosis, an unhealthy imbalance in microbial communities, may help explain why obesity and insulin resistance cluster in the same people.

How microbes aid cancer

Scientists have also noticed that some bacterial species are far more common inside colorectal tumors than in nearby healthy tissue.

One early genomic study found that Fusobacterium sequences were highly enriched in cancer samples compared with matched normal colon tissue.

Laboratory experiments suggest that Fusobacterium can activate inflammatory pathways, interfere with DNA repair, and blunt the immune cells that normally attack emerging tumors. 

Other microbes, including certain strains of Escherichia coli, make toxins that damage DNA in colon cells and leave lasting scars in their genomes.

Because these microbial fingerprints differ between healthy and cancerous tissue, they can be measured in stool samples.

The review points to screening tools that could add microbial markers to current colon cancer tests and help flag higher risk earlier.

How to support microbes

Diet is one of the most powerful levers for shifting gut microbes, and some experiments show how fast those changes happen.

In one study, African American volunteers ate a high fiber, low fat diet for two weeks while rural Africans tried a Western menu.

The high fiber menu boosted protective fermentation products and lowered bile acids tied to cancer risk, while the Western menu did the reverse. 

These findings underline that everyday choices, like eating more beans, whole grains, fruits, and vegetables, help gut microbes produce compounds that protect the colon.

Highly processed foods full of fat, sugar, and additives tend to push microbial communities toward more inflammation and extra energy harvest. Over time, that shift may lock in both weight gain and a colon environment friendlier to tumor growth.

Obesity, cancer, and microbiota

Beyond diet, doctors are testing ways to change gut microbes more directly, including probiotics and fecal microbiota transplantation (FMT), the transfer of screened stool from a healthy donor into another person’s intestines to reset their microbial community. 

Regulators are now approving standardized microbiota therapies, and the first FDA approved fecal microbiota product was cleared in 2022 to prevent recurrent Clostridioides difficile infections in adults.

Although that condition differs from obesity or colorectal cancer, it shows that live microbial products can be regulated and prescribed like other drugs.

This opens the door to more targeted microbiome based treatments for metabolic disease and cancer in the future.

Fair microbiome progress

In the United States, obesity and colorectal cancer do not strike all communities equally, with higher burdens in Black, Hispanic, and low income neighborhoods. 

Microbiome research that only enrolls people from a few backgrounds risks designing tests and treatments that work poorly for everyone else.

One tool for untangling this complexity is Molecular Pathological Epidemiology, a field that links tumor features with lifestyle and exposure data in large studies. 

By connecting tissue changes with how a person lives, it aims to spot combinations of exposures and microbes that push specific cancers forward.

“The emerging discipline of Molecular Pathological Epidemiology integrates lifestyle, microbiome, and biomarker data,” said Moseeb. 

He sees this framework as a way to turn data on diet, pollution, and medications into practical guidance about who needs which screening tests.

For now, gut microbiome science is still being translated from lab benches and cohort databases into doctor offices and community clinics. 

If health agencies, clinicians, and communities work together, gut microbes could help reduce the load of these conditions for future generations.

The study is published in Oncoscience.

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