High-fiber, low-fat diet can restore gut microbiome after antibiotics

Mice fed a Western-style diet cannot rebuild a healthy, balanced gut microbiome after antibiotic treatment, flag researchers from the University of Chicago, US. However, on a diet that mimics a Mediterranean diet, the mice were able to restore a healthy and resilient gut microbiome after antibiotics quickly.

In addition, mice eating a high-fat, low-fiber Western-style diet were more susceptible to infection by pathogens like Salmonella. The researchers note that these mice had a lower variety of microbes in the digestive system and metabolites, which increases the risk for immune system-related conditions, such as inflammatory bowel disease. 

“We were surprised by how dramatically different the recovery process is in the mice on the Western-style diet versus the healthier one,” says lead author Megan Kennedy, a student in the Medical Scientist Training Program at the university.

Instead of transplanting fecal microbiota from healthy subjects to restore a healthy balance in the gut, the authors recommend using diet to treat infections in patients following cancer treatment or organ transplants, who often receive potent antibiotics. 

They conclude that their data “demonstrate that specific dietary interventions are, at a minimum, an essential prerequisite for effective fecal microbiota transplant and may afford a safer, more natural and less invasive alternative.”

Impact of antibiotics

The study, published in Nature, sought to investigate how overuse of antibiotics and Western diets, high in processed foods, red meat, dairy, and sugar, affect gut health. They note that antibiotics can devastate the gut microbiome, as they can wipe out entire microbial communities, both disease-causing pathogens and “good” bacteria. 

They fed mice either a regular, low-fat mouse chow with diverse plant fiber sources or food mimicking a typical Western-style diet. The researchers treated both groups with antibiotics, after which some mice continued the same diet and some switched to the other diet. 

After the mice received the antibiotics, the team reintroduced microbes to them through fecal microbiota transplants, which aim to restore a healthy equilibrium in the gut microbiome by transferring microbes from the stool of healthy animals to other animals. 

The authors suggest using diet to treat infections in patients following cancer treatment or organ transplants, who often receive potent antibiotics.However, when the researchers analyzed the microbes in these test groups, they found that only the mice on their regular diet could recover a healthy microbial equilibrium before and after receiving antibiotics.  

“The mammalian gut microbiome is like a forest, and when you damage it, it must have a succession of events that occur in a specific order to restore itself to its former health,” explains senior author Eugene Chang, professor of Medicine at the University of Chicago. 

“When you are on a Western diet, this does not happen because it doesn’t provide the nutrients for the right microbes at the right time to recover. Instead, you end up with a few species that monopolize these resources and don’t set the stage for other organisms required for recovery.”

Crucial foundation for a diverse microbiome

Additional analysis concluded that the low-fat, high-fiber Mediterranean-style diet promotes networks of metabolites that set the stage for microbes to rebuild a healthy ecosystem. 

At the same time, fecal microbial transplant had a negligible impact on microbiome recovery in mice on the Western-style diet after antibiotics.  

“It doesn’t seem to matter what microbes you’re putting into the community through fecal microbial transplant, even if it’s matched in every way possible to the ideal transplant,” stresses Kennedy. 

“If the mice are on the wrong diet, the microbes don’t stick, the community doesn’t diversify, and it doesn’t recover.”

Fecal microbial transplant had a negligible impact on microbiome recovery in mice on the Western-style diet after antibiotics.The researchers say their findings demonstrate how diet builds a crucial foundation for a diverse, robust, and resilient gut microbiome. In addition to promoting overall good health, they suggest using diet to treat infections in patients who take powerful antibiotics or immunosuppressant drugs, which can lead to infections with multidrug-resistant bacteria. 

“Maybe we can use diet to rebuild the commensal microbes that have been suppressed under these therapies,” suggests Chang. “We can restore the healthy microbiome much quicker and prevent the emergence of more multidrug-resistant organisms.”

Increase fruit and vegetable intake

The authors underscore the importance of increasing fruit and vegetable consumption for gut health. Kennedy suggests that people add more healthy foods to their diet before undergoing surgery that requires antibiotics. 

In addition, Chang examines how people may take personalized supplements to bolster their gut health without drastic dietary changes. 

“I’ve become a believer that food can be medicinal,” he says. “Food can be prescriptive, because we can ultimately decide what food components affect which populations and functions of the gut microbiome.”

Research continuously supports nutrition-based interventions’ health and economic benefits in a growing Food is Medicine movement. A review of such interventions published this month calls for making food a key part of lifestyle medicine. 

Meanwhile, researchers at the US Food is Medicine Institute predict that medically tailored meals could save the US US$32.1 billion in healthcare costs in one year if implemented nationwide. 

In addition, a study examining midlife diets and health outcomes of over 105,000 participants concluded that dietary patterns rich in plant-based foods, moderate healthy animal-based foods, and lower ultra-processed food intake enhance healthy aging.