The Latest Research on the Gut-Brain Axis—And What It Means for You

Your brain is so much more than a matrix of cells and neurons. It’s the central command center that makes you you, and it’s constantly shaping—and being shaped by—every system of your body. 

And according to Sarkis Mazmanian, Ph.D., award-winning microbiology researcher and Seed Scientific Advisor, one of the brain’s most intricate and interesting relationships may just be the one it shares with the gut.

He calls the gut-brain axis “one of the most rapidly advancing areas of biomedicine,” pointing to recent discoveries on the specific bacterial species and microbial molecules that are associated with anxiety and depression, and the role that stress and anxiety play in the health of the gut microbiome.^1,2 

“This work may teach us ways to better cope with real or perceived stress, and reduce/prevent the effects of stress on mental health,” Dr. Mazmanian tells Seed.

In honor of World Brain Day (July 22)—an annual event to spread awareness of the neurological disorders affecting 43.1% of the global population—we asked Dr. Mazmanian all about the gut-brain axis and actionable ways to support it.³ Read on for the full conversation, and review our gut-brain cheat sheet at the end.

What has your lab uncovered about the gut-brain axis recently?

We have recently discovered that in mouse models, specific molecules produced in the gut bacteria can travel to the brain, interact with specific brain cells, and change emotional behaviors such as anxiety.⁴

It is remarkable that gut bacteria have figured out how to send signals to the brain from the gut to regulate complex outcomes. The more we learn about this process, the better we can harness the body’s natural communications systems to the brain for health benefits.

There are also encouraging results that microbiome profiles may serve as diagnostics for various brain disorders such as autism, depression, and Parkinson’s disease (PD), though this work needs additional development and validation.^5,6

What are some of the most promising applications of gut-brain axis research?

Medications for many behavioral, psychiatric, and neurodegenerative disorders have to reach the brain to work. This poses problems as it is very difficult to get pharmaceutical drugs into the brain, which also leads to most of their side effects. 

The gut-brain connection offers the potential to address brain disorders or mental health issues by overcoming this obstacle since drugs only need to be delivered to the gut (orally) to have impacts on the brain, which is much less challenging and likely safer and better tolerated.

What’s the single most important thing readers can do to support their gut-brain axis? 

The best thing you can do to support a healthy gut-brain connection, at least in 2024, is eat a balanced plant-based, minimally processed diet that is low in fat and sugar, and take certain probiotics that improve gut function.

Are there any particular foods you recommend for the gut and the brain? 

A diverse plant-based diet (i.e., many different kinds of plants, seeds, nuts, etc.) is likely the most effective way to foster a healthy gut-brain connection. 

The rationale is that human health positively correlates with a diverse gut microbiome, and people who eat diverse plant-based diets tend to have diverse gut microbiomes.⁷ The mechanisms by which microbial diversity benefits health are not fully understood, but likely result from different chemicals produced by beneficial microbes that can directly or indirectly improve brain function.

What role does sleep play in the gut-brain axis? 

Sleep has been recently shown to improve function of the nervous system. Our brains and perhaps other organs such as the intestines, which have many neurons, are cleansed during sleep to remove buildup of harmful molecules. 

The most research in this area has been in neurodegenerative disorders such as Alzheimer’s disease, where sleep is correlated with better outcomes.⁸ The converse is also true: Altering your circadian rhythm (via sleep deprivation) has negative impacts on brain function and most prominently on metabolism and weight gain.⁹

What about exercise—does that seem to impact the gut-brain axis at all? 

Exercise profoundly and positively impacts the brain in a number of ways. Exercise reshapes the gut microbiome to a healthier profile and thus releases specific health-benefiting molecules that improve gut function.¹⁰ 

Exercise also increases blood flow, which brings oxygen and nutrients that nourish the brain.

Do some people actually have a “stronger” gut-brain axis than others? 

We are not sure, but it does appear that some people do have altered gut-brain communications that are associated with certain disorders such as irritable bowel syndrome. 

Gut issues like IBS are on the rise in the U.S. Could this be connected to declines in mental health? 

In my opinion, disorders such as IBS are strongly influenced by stress. Thus, increased stress can manifest primarily in altered gut function (such as IBS symptoms). In turn, an unhealthy gut can reduce brain health.

What’s next for your research? What gut-brain axis hypotheses are exciting you right now?

While we study many aspects of the gut-brain connection, I am most excited about its implications in diseases of aging such as Parkinson’s disease. We are investigating how signals from the gut to the brain cause PD, and how interrupting these signals or re-wiring to promote healthy signaling may overcome the progression of PD symptoms. 

We are also becoming interested in how the gut-brain connection regulates feeding behaviors, and whether certain probiotics may reduce binge eating.

This interview has been lightly edited and condensed for clarity.