Ageing has long been associated with decreased gastrointestinal (GI) function and adaptive capacity. It is also associated with changes in the composition of gut microbiota. A review by Ran An et al (2018) analyzed the association between age-related changes in gut microbiota and ageing.
Summary | The gut microbiota may be a potential target to improve health outcome in various elderly populations, such as the frail elderly, those with specific comorbid conditions and/or medication use (1). More research is needed on the impact of gut microbiota manipulation, using a targeted approach and with a focus on well characterized and relevant elderly populations.
This figure of Ran et al (2018) shows non-exclusive listing of key changes in GI function and the intestinal microbiota during ageing, including potential influencing factors as well as interventions to beneficially manipulate the intestinal microbiota
*Frailty related; ≈no significant difference; a few or the minority of studies
showing a significant increase; several or the majority of studies showing a significant increase; a few or the minority of studies showing a significant decrease; several or the majority of studies showing a significant decrease. CCK, cholecystokinin; NK, natural killer; NR, not reported. This figure is used with permission from the journal BMJ (1).
According to the review, it is difficult to define a ‘typical’ gut microbiota for the elderly. There has been inconsistent findings for gut microbiota composition among the frail elderly, healthy elderly, centenarians and young adults (1). This may be due to the large interindividual variation and wide range of potential confounding factors.
The gut microbiota of the elderly is more likely to be influenced by factors such as lifestyle (i.e., diet and smoking), comorbidity, medical treatment and living situation rather than by ageing per se. The wide range of potentially confounding factors make it difficult to discover the causes and consequences of age-related alterations in the gut microbiota.
Generally, ageing is linked to various changes in gastrointestinal (GI) physiology and function, which can affect the amount and types of nutrients delivered to the small intestine and colon. This can lead to changes in the composition and functionality of the gut microbiota. An example is impaired masticatory function and taste, which is more pronounced in the frail elderly. The impaired masticatory function and taste causes reduced food intake and poor nutritional status. The decline in nutritional status can in turn affect the composition and activity of gut microbiota. However, the direct impact of age-related alterations in GI function on nutrient digestion and absorption, as well as on the intestinal microbiota composition and functionality remains a point for research (1).
As the gut microbiota is linked to various body functions, it may be a potential target for improved health outcomes in some elderly subgroups. The review recommended for future research to focus on the role of GI physiology and gut microbiota, and their role in specific, well-characterized elderly subgroups (1).
- An R, Wilms E, Masclee AAM, Smidt H, Zoetendal EG, Jonkers D. Age-dependent changes in GI physiology and microbiota: time to reconsider? Gut 2018; 67(12): 2213-2222. https://gut.bmj.com/content/67/12/2213