A small swallowable pill containing modified bacteria can detect intestinal bleeding by glowing on contact with heme, a component of blood dye. Initial tests in mice have shown that this could serve as a rapid and non-invasive method of monitoring intestinal disease. Such diagnostics could help detect problems such as inflammatory bowel disease, infections or bleeding caused by polyps or colon cancer. The advantage is that the pill makes it possible to monitor the condition of the bowel without the need for invasive examinations. Results so far have come from experimental animal studies, with further research needed to confirm efficacy in humans. This technology could improve the early diagnosis and treatment of intestinal diseases.