New findings from researchers at Cleveland Clinic, a top American hospital, show for the first time that the gut microbiome impacts stroke severity and functional impairment following stroke. The results, published in Cell Host & Microbe, lay the groundwork for potential new interventions to help treat or prevent stroke.

The research was led by Weifei Zhu, Ph.D., and Stanley Hazen, M.D., Ph.D., of Cleveland Clinic’s Lerner Research Institute. The study builds on more than a decade of research spearheaded by Dr. Hazen and his team related to the gut microbiome’s role in cardiovascular health and disease, including the adverse effects of TMAO (trimethylamine N-oxide) – a byproduct produced when gut bacteria digest certain nutrients abundant in red meat and other animal products.

“In this study we found that dietary choline and TMAO produced greater stroke size and severity, and poorer outcomes in animal models,” said Dr. Hazen, chair of the Department of Cardiovascular & Metabolic Sciences and director of Cleveland Clinic’s Center for Microbiome & Human Health. “Remarkably, simply transplanting gut microbes capable of making TMAO was enough to cause a profound change in stroke severity.”

Previously, Dr. Hazen and his team discovered that elevated TMAO levels can lead to the development of cardiovascular disease. In clinical studies involving thousands of patients, they have shown that blood levels of TMAO predict future risk of heart attack, stroke and death - findings that have been replicated around the world. Earlier studies, also led by Drs. Zhu and Hazen, were the first to show a link between TMAO and enhanced risk for blood clotting.

“This new study expands on these findings, and for the first time provides proof that gut microbes in general – and through TMAO specifically – can directly impact stroke severity or post-stroke functional impairment,” said Dr. Hazen.