Western diet disrupts intestinal recovery and increases risk of infection

According to a study published this week by the University of Chicago, a high-fat, low-fiber Western diet seriously impairs the gut microbiome’s ability to recover from antibiotic treatments, which may leave individuals vulnerable to dangerous infections.

The study shows that mice consuming Western diets suffered a long-term microbiome damage after antibiotics, while those mice consuming fiber-rich foods recovered quickly through natural succession processes, thus restoring microbial diversity and protective functions.

“We were really surprised how different the recovery process in the Western diet is from a healthier diet,” said Megan Kennedy, lead author and student of the Uchigago Medical Scientist Training Program.

The research team, led by Eugene B. Chang, professor of medicine at Uchicago, found that after a carefully planned series of ecological steps, mice with a conventional food diet (high plant fiber content and low fat) quickly reconstructed their gut microbial community after antibiotic treatment. By contrast, mice with a Western diet (high fat, low fiber) remained at least nine weeks in severely damaged states.

This disruption makes Western diet mice susceptible to Salmonella infections, which usually fail to establish infections in mice with healthy gut communities.

The researchers used complex metabolic modeling to reveal why the dietary environment affects recovery so much. Their analysis shows that a fiber-rich diet promotes beneficial cross-eating relationships between different bacterial species—basically creating an ecosystem in which microorganisms support each other’s growth through metabolic byproducts.

However, the Western diet promotes dominance through a bacterial strain that monopolizes available nutrients without supporting community diversity. This ecological imbalance prevents the development of healthy, complex microbial communities that can resist pathogens.

Chang compared the effects of antibiotics on gut bacteria to forest fires. “The gut microbiome of a mammal is like a forest, and when you damage it, it must have a series of events that happen in a specific order to restore itself to its former health,” he explained. “When you are on a Western diet, this doesn’t happen because it doesn’t provide nutrition to the right microorganisms at the right time.”

Perhaps most surprisingly, the team found that fecal microbiota transplant (FMT) (FMT), a program that introduces healthy bacteria from donors, was ineffective in restoring the microbial community of mice in Western diets. Only dietary interventions can successfully restore the health of the microbiome.

“Even if you match your ideal transplant in all possible ways, what microorganisms can be put into FMT,” Kennedy noted. “If the mice have a wrong diet, the microorganisms won’t stick, the community won’t diversify, and they won’t recover.”

These findings represent a paradigm shift in our understanding of microbiome recovery. Although FMT has become a treatment for stubborn intestinal infections, this study suggests that dietary interventions may be a more basic approach to microbiome recovery.

This study has had a significant impact on human health, especially given Americans’ high consumption of Western-style diets and frequent use of antibiotics. Patients receiving cancer treatment or organ transplants often receive multiple antibiotic courses that may benefit from dietary interventions that rebuild a healthy gut community.

The study also highlights the potential of food as medicine. “I already believe food can be medicinal,” Chang said. “In fact, I think food can be prescriptive because we can ultimately decide which food ingredients affect the population and function of the gut microbiome.”

For those about to be treated with antibiotics, the study shows that consumption of fiber-rich foods such as fruits, vegetables, and whole grains may help their gut microbiome recover faster.

Now, researchers are exploring ways to achieve similar benefits without the need for huge dietary changes, which can support target supplements for microbiome recovery even in suboptimal diets.

The study was supported by collaborators from the National Institutes of Health, the Chicago Gastrointestinal Research Foundation, the Simmons Foundation, the U.S. Department of Energy, and the Chinese University of Hong Kong.