How Long Poop Stays in Your Body Could Be Quietly Shaping Your Gut Microbiome – And Disease Risk - ScienceAlert

What the report says

ScienceAlert reports that the time it takes food waste to move through the body — known as gut transit time — may be an underappreciated factor in shaping the gut microbiome and, potentially, disease risk. The article, published July 30, 2026, summarizes a 2023 review in the journal Gut by researchers from Denmark and Belgium, led by University of Copenhagen microbiome researcher Henrik Roager. The review examined existing studies and argued that transit time is often overlooked in human microbiome research despite evidence that it helps explain differences in fecal microbial communities between people.

According to ScienceAlert’s account of the review, gut transit time varies widely and can be influenced by diet, food composition, sex, age, physical activity, stress, medication and genetics. The researchers noted that transit is generally shorter in men and tends to lengthen with age, while also fluctuating within individuals. These differences may matter because they can alter which microbes thrive and what metabolic byproducts they produce.

The article says prolonged or shortened transit may have consequences for gastrointestinal conditions, including links discussed in the review with irritable bowel syndrome, inflammatory bowel disease and constipation. The researchers also highlighted broader associations between altered bowel habits and diseases beyond the gut, including Parkinson’s disease, Alzheimer’s disease and multiple sclerosis, while emphasizing that many causal pathways remain uncertain.

ScienceAlert notes that the review does not prove that a specific transit time is inherently healthy or harmful. Rather, it calls for gut transit measurements to be included more often in microbiome studies, so researchers can better understand how diet, microbes and disease are connected and whether that knowledge could improve prevention, diagnosis or treatment.