High-Fat Diet & Colorectal Cancer Risk | Gut Bacteria Study
- A new study from the Salk Institute and UC San Diego suggests a connection between high-fat diets, changes in gut bacteria, and an increased risk of colorectal cancer.
- 22,2023,in Cell Reports,highlights how diet can influence the gut microbiome and potentially create conditions favorable for cancer development.
- "The balance of microbes in the gut is shaped by diet, and we are discovering how alterations in the gut microbial population (the gut microbiome) can create problems...
Discover the link between high-fat diets and increased colorectal cancer risk. New research reveals that high-fat diets can trigger changes in gut bacteria, which then alter bile acids, possibly leading to inflammation and increased cancer risk. Studies show how a high-fat diet influences the gut microbiome and reshapes bile acid pools, fostering a disease-associated state via specific bacteria. News Directory 3 keeps you in the know with the latest health breakthroughs. Learn how modified bile acids from certain bacteria, like Ileibacterium valens and Ruminococcus gnavus, impact intestinal stem cell proliferation and contribute to the development of cancer. Discover what’s next regarding methods to reverse these effects.
High-Fat Diets Linked to Gut Bacteria Changes, Increasing Colorectal Cancer Risk
Updated June 29, 2025
A new study from the Salk Institute and UC San Diego suggests a connection between high-fat diets, changes in gut bacteria, and an increased risk of colorectal cancer. Researchers found that high-fat diets in mice led to specific changes in gut bacteria,which in turn altered bile acids,digestive molecules that can promote inflammation and affect intestinal stem cell replenishment.
The research, published Aug. 22,2023,in Cell Reports,highlights how diet can influence the gut microbiome and potentially create conditions favorable for cancer development. Bile acids, produced by the liver, aid in the digestion of fats, cholesterol, and nutrients.
“The balance of microbes in the gut is shaped by diet, and we are discovering how alterations in the gut microbial population (the gut microbiome) can create problems that lead to cancer,” said Professor Ronald Evans, director of Salk’s Gene Expression Laboratory.
The team’s work builds on previous findings from 2019, which showed that high-fat diets in mice increased overall bile acid levels, shutting down a key gut protein and increasing cancer prevalence. The current study further investigates how the gut microbiome and bile acids are affected by these diets.
The scientists examined the microbiomes and metabolomes in mice with a genetic predisposition to colorectal tumors.They discovered that while high-fat diets increased bile acids, the collection was less diverse and contained more of certain bacteria-modified bile acids. These modified bile acids impacted the proliferation of stem cells in the intestines. Reduced stem cell replenishment can lead to accumulated mutations, a critical step in cancer development.
“We are only just begining to understand these bacterially-conjugated bile acids and their roles in health and disease,” said michael Downes, a staff scientist at Salk.
The study also revealed that high-fat diets considerably altered the gut bacteria composition, with less diversity and the presence of different bacteria compared to mice on normal diets. Ileibacterium valens and Ruminococcus gnavus were identified as bacteria capable of producing the modified bile acids.
Interestingly, the impact of a high-fat diet on the microbiome and modified bile acids was greater than the impact of a genetic mutation that increases cancer susceptibility.
“We’ve pinpointed how high-fat diet influences the gut microbiome and reshapes the bile acids pool,pushing the gut into an inflamed,disease-associated state,” said Ting Fu,former postdoctoral fellow in the Evans lab.
Researchers believe that high-fat diets encourage the growth of bacteria like I. valens and R. gnavus, leading to increased levels of modified bile acids. This creates an inflammatory surroundings that further alters the gut bacteria composition.
“We’ve deconstructed why high-fat diets aren’t good for you,and identified specific strains of microbes that flare with high-fat diets,” Evans said.
What’s next
Future research will focus on the speed at which the microbiome and bile acids change after starting a high-fat diet,as well as methods to reverse the cancer-associated effects by targeting the FXR protein.