Your gut microbiota — the trillions of tiny bacteria, viruses, and fungi dwelling deep within your intestinal tract — play a big role in your health. Beyond helping with digestion, these microbes also make certain nutrients and release substances that have wide-ranging effects throughout the body, including on the cardiovascular system. To continue reading this article, you must log in . Subscribe to Harvard Health Online Plus (HHO+) to unlock expert-backed health insights, personalized tools,