When breathing stops dozens of times each night, the damage spreads far beyond the lungs—it travels through the gut, reshaping the microscopic ecosystem that may protect the heart. Researchers at UC San Diego have uncovered a surprising link between obstructive sleep apnea and cardiovascular disease, one rooted in the way gut microbes communicate with the body through chemical compounds called bile acids. The discovery, presented at ASM Microbe 2026, suggests that millions of people living with this common sleep disorder may one day benefit from therapies targeting the gut itself.
Sleep apnea silently damages the heart by repeatedly depriving the body of oxygen throughout the night. These interruptions trigger harmful changes in bile acids—substances produced by the liver that normally help digest fats but also act as chemical messengers, signaling to cells and tissues far beyond the digestive tract. When oxygen drops, bile acids change shape, and the microbes in the gut can modify them further. For years, researchers suspected these microbially altered bile acids played a crucial role in the cardiovascular complications of sleep apnea, but the exact mechanism remained a mystery.
Celeste Allaband, the study's first author, and her team set out to test a specific hypothesis: what if they removed the main receptor that bile acids use to communicate with the body? To find out, they studied two groups of mice genetically prone to heart disease. One group had the normal genetic makeup, while the second group was missing the farnesoid X receptor, or FXR—the primary docking station where bile acids deliver their signals. Both groups were then exposed to conditions that mimicked sleep apnea, with researchers tracking changes in gut microbes and analyzing arterial plaque buildup over time.
The results were striking. Mice without the FXR receptor developed significantly less plaque in their aortas and aortic arches during simulated sleep apnea—showing that blocking bile acid signaling through FXR protected against one of sleep apnea's most dangerous consequences. The researchers also noticed that the gut microbiome itself remained more stable and less disrupted when FXR was absent. "Strikingly, when this receptor was removed from the mice, the development of arterial plaques dropped significantly in some areas and disruptions to the gut microbiome were minimized," Allaband explained.
The findings open a new frontier in sleep apnea treatment. Rather than focusing solely on keeping airways open at night, doctors might one day prescribe targeted therapies that modify how bile acids signal in the body, or introduce beneficial microbes as preventive probiotics. Allaband's team is already planning the next steps: examining datasets from human sleep apnea patients to see if the same patterns hold in people, testing whether supplementing specific bile acids can prevent disease, and exploring whether key microbes could be given as a probiotic to reduce cardiovascular risk.
If these laboratory discoveries translate to human treatment, they could transform care for the millions of people living with sleep apnea—shifting the focus from the bedroom to the gut, and offering new hope for preventing heart disease before it takes hold.