The intestinal barrier is a protective layer that lines the intestines, playing a crucial role in maintaining gut health. It consists of epithelial cells that are tightly joined together, preventing harmful substances, such as bacteria and toxins, from entering the bloodstream while allowing nutrients to pass through. This barrier also includes a layer of mucus and immune cells that help defend against pathogens. When the intestinal barrier is compromised, it can lead to conditions like leaky gut syndrome, where unwanted substances leak into the body, potentially causing inflammation and other health issues.