Ageing and the gut

Abstract

The goal of this brief review is to address the role of the ageing gut in the genesis of malnutrition in the elderly. We assess the burden of malnutrition in the elderly, exploring the role of comorbid conditions and neurohumoral changes that take place to contribute towards the process of anorexia associated with ageing. Following this, the review assesses physiological changes that occur in each part of the gastrointestinal (GI) tract and what implication they may have in clinical practice. In the oropharynx and the oesophagus, changes in swallowing and oesophageal motility associated with ageing can be demonstrated using physiological testing. However, in the absence of comorbid disease, they often have little, if any, clinical significance. In the stomach, reduced fundal compliance may contribute to early satiety; however, the primary change is hypochlorhydria, which may predispose to malabsorption or bacterial overgrowth further along the GI tract. Almost uniquely, the small bowel, particularly its absorptive function, is unaffected by age and we review the literature demonstrating this. In the colon, there is evidence of a prolonged transit time related to a reduction in both neurotransmitters and receptors. Although this may cause symptoms, this aspect is unlikely to contribute to malnutrition. In addition, we assess the potential changes in the gut microbiome and how this may interact with the immune system in the process of ‘inflamm-ageing’. We conclude by summarising the main changes and their impact for the clinician along with recommendations for future areas of research.

Diet and the development of the human intestinal microbiome

“…Decline in physical mobility may limit access to the grocery store or inhibit the ability to cook. Some elderly lose the desire to eat due to loss of smell and taste or due to slow digestion and prolonged satiety (Britton and McLaughlin, 2013). Malnutrition is often an unintended consequence of age-related physiological changes that can lead to changes in the elderly gut microbiome.…”

Intestinal morphology adjustments caused by dietary restriction improves the nutritional status during the aging process of rats

“…It is known that the aging process is associated with a significant number of morphological and functional abnormalities of the gastrointestinal tract, including: the reduced amplitude and frequency of gastric emptying and peristaltic movements, which cause slow intestinal transit (Parker and Chapman, 2004;Schoffen and Natali, 2007); impairment of digestion and nutrient absorption (Schoffen and Natali, 2007) due to lower production of digestive enzymes (Parker and Chapman, 2004;Steegenga et al, 2012); changes in the composition of the intestinal microbiota as a consequence of eating habits (Steegenga et al, 2012;Britton and Mclaughlin, 2013); atrophy of the intestinal mucosa, leading to reduction in its activity (Grattagliano et al, 2004); an increase in the cell cycle (Thrasher and Greulich, 1965;Cirilo et al, 2013); reduction in the apoptotic index of epithelial cells (Holt et al, 1998;Xiao et al, 2001); and (6) neurodegeneration in the enteric nervous system (Drozdowski and Thomson, 2006;Schoffen and Natali, 2007;Cirilo et al, 2013;Mello et al, 2013;Rayner and Horowitz, 2013).…”

Medium-term effects of dietary nitrate supplementation on systolic and diastolic blood pressure in adults

“…A correct anti-hypertensive drug therapy combined with dietary and lifestyle modifications 30 attenuate the adverse effects of BP on cardiovascular health; however adequate and sustained 31 control of BP using these combined approaches is only achieved in ~60-70% of hypertensive 32 patients [3]. Therefore, the primary prevention of hypertension becomes a priority to 33 minimise the population burden of hypertension and nutritional and lifestyle approaches are 34 unanimously recognised as fundamental components of primary prevention programmes [4].…”

“…to NO [30]. Ageing may also be associated with changes in oral microflora and gastric acid 209 production which may influence the efficiency of the conversion of nitrate into NO [31,32]. of BP [38,39].…”