Lungcast: The Lung-Gut Axis - Where Nutrition & Lung Health Intersect with Neal Barnard, MD

Nutrition has long been recognized as a pillar of health, but only in recent decades has science begun to unravel its profound influence on the microbial ecosystems that inhabit our bodies. Central among these is the gut microbiome, a dynamic and diverse collection of microbes that perform essential roles in metabolism, immunity, and even neural signaling. Accumulating evidence has linked alterations in the gut microbiome to the risk and progression of numerous chronic diseases, including inflammatory bowel disease, obesity, cardiovascular disease, and certain cancers. As research continues to map the interplay between diet and microbial diversity, the therapeutic potential of modulating the microbiome through nutrition is becoming increasingly compelling.

But the microbiome’s reach doesn’t stop at the gut. Once considered sterile, the lungs are now understood to host their own microbial communities—albeit at lower densities and with distinct characteristics compared to the gastrointestinal tract. The discovery of the lung microbiome, confirmed by culture-independent techniques in the early 2010s, has reshaped long-standing assumptions in respiratory medicine. Alongside this has emerged the concept of the gut-lung axis: a bidirectional communication pathway whereby changes in the gut microbiome may influence lung immunity and inflammation, and vice versa. This axis is believed to be particularly relevant in chronic lung diseases such as asthma, chronic obstructive pulmonary disease, and interstitial lung disease, where immune dysregulation and microbial imbalance often coexist.

In this episode of Lungcast, host Albert Rizzo, MD, is joined by Neal Barnard, MD, Adjunct Associate Professor of Medicine at the George Washington University School of Medicine and Health Sciences and president of the nonprofit Physician's Committee for Responsible Medicine, to explore how nutrition shapes both the gut and lung microbiome, and what that means for the prevention and management of chronic respiratory diseases. Together, they examine the emerging science linking diet, microbial balance, and lung health—and why clinicians should pay closer attention to the microbial threads connecting what we eat to how we breathe.

"The gut is not sterile, the lungs are not sterile, and perhaps most worrisome of all, the brain is not sterile," Barnard said. "But if our diet is a healthful diet, we are selected for good immunity and for hopefully casting out the more pathogenic microorganisms."

Lungcast is a monthly respiratory news podcast series hosted by Albert Rizzo, MD, chief medical officer of the ALA, and produced by HCPLive.

Subscribe to Lungcast on Spotify here, or listen to the episode below.

REFERENCE

Lipinksi JH, Ranjan P, Dickson RP, O’Dwyer DN. The Lung Microbiome. J Immunol. 2024;212(8):1269-1275. doi: 10.4049/jimmunol.2300716