A modern Western-style diet rich in processed foods, red meat, dairy, and sugar, and low in fruits, vegetables, and whole grains significantly alters the gut microbiome reducing microbial diversity and beneficial metabolites. This shift increases the risk of immune-related conditions like inflammatory bowel disease.

In a new study published in Nature researchers from the University of Chicago found that mice fed a Western-style diet struggled to restore a healthy diverse gut microbiome after antibiotic treatment and were more vulnerable to infections such as Salmonella. In contrast, mice given a diet resembling the Mediterranean style high in plant-based fiber from fruits, vegetables, and whole grains recovered quickly and maintained a more resilient gut microbiome.

We were really surprised by how dramatically different the recovery process is in the mice on the Western-style diet versus the healthier one said Megan Kennedy lead author and Medical Scientist Training Program student at UChicago.

Antibiotics while effective at targeting harmful pathogens can severely disrupt the gut microbiome by indiscriminately eliminating both harmful and beneficial bacteria. This widespread microbial loss can compromise gut health and overall immunity.

Eugene B. Chang, MD, Martin Boyer Professor of Medicine at the University of Chicago and senior author of the study, compares this disruption to a forest fire requiring a structured ecological succession for recovery. Co-author Joy Bergelson, PhD, formerly of UChicago and now at NYU and the Simons Foundation, brings her expertise in plant-microbe interactions to this microbial analogy.

The gut microbiome functions like a forest said Chang. After damage it needs a sequence of events to recover properly. A Western-style diet disrupts this process by failing to provide nutrients at the right time for the right microbes to repopulate. As a result only a few species dominate, blocking full recovery.

Given the widespread use of antibiotics and prevalence of the Western diet in the U.S., Kennedy and Chang investigated how this combination affects microbiome recovery. In their study, mice were fed either a Western-style diet (WD) or regular chow (RC) rich in plant fiber and low in fat. After receiving antibiotics some mice remained on their original diets, while others were switched to the alternate diet to assess its impact on gut microbial restoration.

Researchers used fecal microbial transplant (FMT) to try restoring gut balance after antibiotics by introducing microbes from healthy mice. However, only mice on the regular chow (RC) diet before or after antibiotics successfully regained a healthy microbial equilibrium. Computational analysis by Argonne’s Christopher Henry revealed that the RC diet supports metabolite networks essential for microbial recovery. In contrast FMT had little effect on mice fed the Western diet (WD) who remained vulnerable to Salmonella infection. As Kennedy noted without the right diet beneficial microbes can’t thrive or restore gut diversity even with FMT.

Kennedy and Chang emphasize that diet lays the foundation for a resilient gut microbiome and could aid recovery in patients after cancer treatments or transplants. While the message is clear eat more fruits and vegetables they acknowledge that drastic dietary shifts aren’t always realistic for everyone.

Source: https://www.newswise.com/articles/food-as-medicine-how-diet-shapes-gut-microbiome-health/?ad2f=1&aid=830986