People with inflammatory bowel disease have a more permeable intestinal barrier than healthy people, even when they are not experiencing symptoms. This is measured by higher levels of two sugars,...

We analyzed the available evidence and found that people with inflammatory bowel disease (IBD) tend to have a more permeable intestinal barrier even when they are in remission and not experiencing symptoms. This conclusion is based on measurements of two sugars—13C-mannitol and lactulose—that appear in higher amounts in urine after being consumed, which suggests the gut lining is letting more substances pass through than it should in healthy individuals [1]. The evidence we’ve reviewed so far includes 58 studies or assertions that support this observation, with none that contradict it. These findings suggest that the gut barrier may remain altered even when inflammation has quieted down. Intestinal permeability, sometimes called “leaky gut,” refers to how easily molecules move through the lining of the intestines. In IBD, this barrier may not fully recover, even during periods of remission. It’s important to note that we are not saying this causes symptoms or disease flare-ups—only that the evidence shows a consistent pattern of increased permeability in people with IBD, regardless of whether they feel well. The exact reasons why this happens, or what long-term effects it might have, are still unclear from the data we’ve reviewed. What this means for someone with IBD in remission is that the gut may still be functioning differently than in someone without the condition. Monitoring diet, stress, or other factors that influence gut health could be worth considering, even when symptoms are absent. But more research is needed to understand how this finding connects to daily health outcomes.