The Ageing Gut, in Health and Disease

There is a global ageing phenomenon, which stress the importance for an improved health for the increased population of older adults. One important factor for a good health is a well-functioning gut. Hence, this thesisinvestigates several aspects of gut health for older adults, spanning from overall gut health in community-dwelling older adults, to investigating a gut disease model: inflammatory bowel disease, which includes Crohn’s disease and ulcerative colitis. When investigating community-dwelling older adults, gastrointestinal symptoms were found to be common and correlated to a lower experience of well-being. In addition, more than half of the population did not reach the recommended intake of several macronutrients, including protein and fibre. Compared to a group of active older adults, still practising orienteering, i.e., senior orienteers, community-dwelling older adult’s further showed signs of a less healthier gut microbiota, including lower levels of Faecalibacterium prausnitzii. By investigating the disease model of inflammatory bowel disease, later onset of Crohn’s disease seemed to have less hyperresponsive adaptive immune response toward the own gut microbiota, which seems to be due to a less genetic predisposition among later onset individuals. Interestingly, an environmental pollutant, per- and polyfluoroalkyl substances (PFAS), was increased in the serum of late-onset ulcerative colitis patients compared to healthy controls. A higher level of PFAS further correlated to a disturbed bile acid pool. In addition, PFAS induced an increased intestinal permeability across ileal and colonic murine tissue. In conclusion, the work included in this thesis further emphasises the importance of a maintained gut health. In addition, the work highlights diet, an active life-style, gut microbiota and environmental factors, for example PFAS, as targets of future interventions studies with the aim to improve gut health and overall health among older adults.