Implicated in Crohn's disease, ulcerative colitis, and IBS. Fiber (butyrate), omega-3s, cocoa/green tea polyphenols, and probiotics such as L. plantarum reduce it.
View the study (meta-analysis) →It is the main vehicle of metabolic endotoxemia, which connects the Western diet with obesity, diabetes, and cardiovascular disease.
View the study (preclinical) →Zonulin rises before the onset of type 1 diabetes; a link between permeability and autoimmunity.
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A single layer of epithelial cells lines the entire digestive tract, facilitating the exchange of nutrients between the gut and the bloodstream, and this layer, called the intestinal epithelium, must be permeable to nutrients but impermeable to pathogens; when gaps form between the tight junctions that join the enterocytes, a phenomenon known as leaky gut, pathogens can cross the intestinal barrier and pass directly into the bloodstream, promoting inflammation through toll-like receptors.
The intestinal barrier has a surface area of approximately 30 square meters, equivalent to that of a small studio apartment, and its multiple layers of defense include the mucus layer secreted by goblet cells, Paneth cells that distinguish friendly bacteria from pathogens, and the gut microbiota that colonizes the space near the mucus layer to displace unfamiliar microorganisms; all of these coordinated defenses protect the body from harmful substances that enter with food and drink.
Intestinal permeability is involved in the pathogenesis of numerous conditions, including Crohn's disease, ulcerative colitis, and other inflammatory bowel diseases in which specific genotypes predispose to increased permeability in response to certain environmental triggers; irritable bowel syndrome, in which an excess of T cells and mast cells compromises the barrier; and type 1 diabetes, in which concentrations of zonulin, a protein that modulates intestinal permeability, rise just before the onset of the disease, suggesting a link between increased permeability and the development of autoimmunity.
Bacterial lipopolysaccharide (LPS) is the main mediator of the systemic damage produced by leaky gut: it exploits permeability to access the bloodstream, where toll-like receptors detect its presence and trigger an immune response that drives protein expression and inflammation, which in turn can contribute to the pathogenesis of cardiovascular, neurodegenerative, and metabolic diseases, behavioral disorders, and cancer, and can also engage with brain microglia to initiate a vicious cycle of neuroinflammation.
Dietary fiber undergoes microbial fermentation to produce butyrate, a short-chain fatty acid that provides more than 70% of the energy of colon cells and strengthens the tight junction proteins that maintain the integrity of the intestinal barrier; whole grains are the main dietary sources of fermentable fiber, but fruits and vegetables such as apples, sunflower seeds, oats, and potatoes also provide pectin, beta-glucans, inulin, and resistant starch that feed butyrate-producing bacteria.
Omega-3 fatty acids reduce intestinal permeability, modify the composition of the gut microbiota by favoring butyrate-producing species, and resolve inflammation through specialized pro-resolving mediators; polyphenols from cocoa and green tea may reduce the risk of intestinal permeability in older adults by supporting populations of butyrate-producing bacteria; and probiotics such as Lactobacillus plantarum can increase the integrity of the intestinal barrier by regulating the tight junction proteins that hold intestinal epithelial cells together.
Information, not medical advice. Scientific evidence reflects the quality of the studies.