The Aging Gut: Physiology

Main Disorders of Gastrointestinal Tract in Older People: An Overview

From a physiological standpoint, aging is a progressive reduction in each organ system’s capacity to maintain homeostasis in the face of illness or stressors. With advancing age, gastrointestinal (GI) symptoms and signs may increase, not only due to the aging processes but also to the superimposed effects of comorbidities, which can badly affect digestive functions (i.e., diabetes, malignancy, etc.) and environmental exposure. In general, gastrointestinal symptoms in older people more often underlie organic pathologies, while GI functional disorders are less frequently diagnosed in this age group. Moreover, gastrointestinal disease can also present in a nuanced and atypical manner, making the diagnostic hypothesis and, consequently, the correct diagnosis and therapy more challenging. In addition, with reference to this age group, the clinical implications of gastrointestinal pathologies can be more severe due to a decreased physiologic reserve, with a higher risk for malnutrition resulting in falls, depression, social isolation, and a deterioration of functional status. In this review, we focused on the most frequent GI tract disorders, highlighting the main age-related changes, their epidemiological, pathophysiological and clinical implications, and any differences with younger patients.

The acute postprandial response of homocysteine to multivitamin and mineral supplementation with a standard meal is not impaired in older compared to younger adults

PURPOSE

B vitamins are required for the complex regulation of homocysteine and one-carbon (1C) metabolism. Nutritional supplements are frequently used by older adults to counter nutritional inadequacies. However, the postprandial use of B vitamins from supplements in 1C metabolism may be altered with age owing to impaired nutrient absorption and metabolic regulation. Despite implications for health and nutritional status, postprandial 1C metabolite responses have not been characterised in older adults.

METHODS

Healthy older (n = 20, 65-76 years) and younger (n = 20, 19-30 years) participants were recruited through online and printed advertisements in Auckland, New Zealand. Participants consumed a multivitamin and mineral supplement with a standard breakfast meal. Blood samples were collected at baseline and hourly for 4 h following ingestion. Plasma 1C metabolites (betaine, choline, cysteine, dimethylglycine, glycine, methionine, serine) were quantified using liquid chromatography coupled with mass spectrometry. Serum homocysteine, folate and vitamin B₁₂ were quantified on a Cobas e411 autoanalyzer.

RESULTS

Older adults had higher fasting homocysteine concentrations (older: 14.0 ± 2.9 µmol/L; younger: 12.2 ± 2.5 µmol/L; p = 0.036) despite higher folate (older: 36.7 ± 17.4 nmol/L; younger: 21.6 ± 7.6 nmol/L; p < 0.001) and similar vitamin B₁₂ concentrations (p = 0.143) to younger adults. However, a similar postprandial decline in homocysteine was found in older and younger subjects in response to the combined meal and supplement. Except for a faster decline of cystathionine in older adults (p = 0.003), the postprandial response of other 1C metabolites was similar between young and older adults.

CONCLUSION

Healthy older adults appear to maintain postprandial responsiveness of 1C metabolism to younger adults, supported by a similar postprandial decline in homocysteine concentrations.

Sarcopenia in Inflammatory Bowel Diseases: Reviewing Past Work to Pave the Path for the Future

Purpose of the Review

Sarcopenia is the loss of muscle quantity and strength. It is highly prevalent in patients with inflammatory bowel disease (IBD) and is associated with periods of ongoing inflammation. This review will summarize the prior work in the field and highlight areas for future research.

Recent Findings

The presence of sarcopenia has been associated with adverse outcomes in different populations. Most recently, sarcopenia has been associated with adverse postoperative outcomes and an increased likelihood of surgery in IBD. Despite this, significant heterogeneity among these studies limits the ability to draw definitive conclusions.

Summary

The importance of sarcopenia in inflammatory bowel disease (IBD) is only beginning to be recognized. Future studies assessing it utility both as a risk stratification tool and a modifiable factor in IBD are needed.

Exploring trajectories in dietary adequacy of the B vitamins folate, riboflavin, vitamins B6 and B12, with advancing older age: a systematic review

Maintaining nutritional adequacy contributes to successful ageing. B vitamins involved in one-carbon metabolism regulation (folate, riboflavin, vitamins B6 and B12) are critical nutrients contributing to homocysteine and epigenetic regulation. Although cross-sectional B vitamin intake in ageing populations is characterised, longitudinal changes are infrequently reported. This systematic review explores age-related changes in dietary adequacy of folate, riboflavin, vitamins B6 and B12 in community-dwelling older adults (≥65 years at follow-up). Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, databases (MEDLINE, Embase, BIOSIS, CINAHL) were systematically screened, yielding 1579 records; eight studies were included (n 3119 participants, 2–25 years of follow-up). Quality assessment (modified Newcastle–Ottawa quality scale) rated all of moderate–high quality. The estimated average requirement cut-point method estimated the baseline and follow-up population prevalence of dietary inadequacy. Riboflavin (seven studies, n 1953) inadequacy progressively increased with age; the prevalence of inadequacy increased from baseline by up to 22·6 and 9·3 % in males and females, respectively. Dietary folate adequacy (three studies, n 2321) improved in two studies (by up to 22·4 %), but the third showed increasing (8·1 %) inadequacy. Evidence was similarly limited (two studies, respectively) and inconsistent for vitamins B6 (n 559; −9·9 to 47·9 %) and B12 (n 1410; −4·6 to 7·2 %). This review emphasises the scarcity of evidence regarding micronutrient intake changes with age, highlighting the demand for improved reporting of longitudinal changes in nutrient intake that can better direct micronutrient recommendations for older adults. This review was registered with PROSPERO (CRD42018104364).

Immune response and gut microbiota of mice on a diet mimicking eating habits of elderly with risk of malnutrition development

The number of elderlies is increasing but prevalence of malnutrition has been reported. The aim of the study was to determine the significance of short-term nutritional deficiencies in mice. Immune status was assessed through flow cytometry of leucocytes in Peyer's patches (PP) and mesenteric lymph nodes (MLN), and intestinal microbiota was evaluated by terminal restriction fragment length polymorphism (T-RFLP). C57BL/6NCrl mice fed standard diet (StD) or experimental diet high in fat, and low in carbohydrates, protein, fibre, vitamins, and minerals (ExpD) for 2 or 4 weeks. ExpD-animals gained less weight, increased liver lipids, and developed splenomegaly. Diet affected regulatory T-cells, gut homing receptors and TLR2 and TLR4 in PP and MLN and the microbiota was influenced. Partial least squares models on flow cytometry- and T-RFLP data demonstrated correlations between microbial communities and immune phenotyping. Our model shows similarities to malnourished elderly and interactions between intestinal bacteria and the immune system.

Age-dependent changes in GI physiology and microbiota: time to reconsider?

Our life expectancy is increasing, leading to a rise in the ageing population. Ageing is associated with a decline in physiological function and adaptive capacity. Altered GI physiology can affect the amount and types of nutrients digested and absorbed as well as impact the intestinal microbiota. The intestinal microbiota is considered a key player in our health, and a variety of studies have reported that microbiota composition is changing during ageing. Since ageing is associated with a decline in GI function and adaptive capacity, it is crucial to obtain insights into this decline and how this is related to the intestinal microbiota in the elderly. Hence, in this review we focus on age-related changes in GI physiology and function, changes of the intestinal microbiota with ageing and frailty, how these are associated and how intestinal microbiota-targeted interventions may counteract these changes.

Diagnostic Comparison of CT Scans and Colonoscopy for Immune-Related Colitis in Ipilimumab-Treated Advanced Melanoma Patients

Colitis can be a life-threatening toxicity for patients treated with immune checkpoint blockade antibodies. With the anticipated widespread use of these reagents, the timely and accurate diagnosis of immune-related colitis becomes increasingly important. To better understand the clinical presentation of colitis from ipilimumab and to assess the use of CT scans of the abdomen/pelvis as a diagnostic tool, we retrospectively analyzed patients with advanced melanoma who received ipilimumab at our institution. Ninety nine (33%) of 303 patients developed diarrhea during therapy, and 46 patients (15%) received corticosteroids for colitis. Of the patients with diarrhea, 48 (48%) underwent colonoscopy and 46 (46%) underwent both CT and colonoscopy. In the 34 patients (34%) with a CT and biopsy, CT was highly predictive of colitis on biopsy (positive predictive value 96%), and the absence of CT findings was predictive of a negative biopsy (negative likelihood ratio 0.2). In patients who had symptoms and CT evaluation, CT was highly predictive of the need for steroids to reach resolution of symptoms (positive predictive value 92%, positive likelihood ratio 7.3). We conclude that CT is a fast, reliable, and noninvasive mode of diagnosing colitis, whereas colonoscopy and biopsy may not be needed to establish that diagnosis. Cancer Immunol Res; 5(4); 286-91. ©2017 AACR.

Infection in the Critically Ill Older Adult

Many challenges exist in caring for older adults with infection in critical care environments. Older adults are at high risk due to diminished reserve, age-related changes, comorbidities, subtle clinical presentations, and institutionalization. Additional risks include infections, such as pneumonia, influenza, and nosocomial infections. Age-related changes contribute to the increased risk of infection in older adults. Nursing assessments should be tailored to the needs of the older patient. To improve health care outcomes in this population, nursing care of the critically ill older adult with infection should include comprehensive assessment, surveillance for risks, and strategies aimed to aggressively treat infection.

A scoping review of anorexia of aging correlates and their relevance to population health interventions

Anorexia of aging (AA, i.e., loss of appetite and/or reduction of food intake with aging) is an important public health issue. It leads to unintentional weight loss, which is an independent risk factor for morbidity and mortality among seniors. AA has mainly been studied from a biological perspective and regarded as a normal physiological consequence of aging, rather than a negative health outcome with underlying determinants. Some potentially modifiable correlates have however been found to be associated with this geriatric condition. Here, we conducted a scoping review of the literature to: 1) identify AA correlates, and 2) discuss their relevance to population health interventions. Our results indicate two main categories of AA correlates, namely, physiopathological and non-physiopathological. The first category relates to physiological dysfunctions, pathologies involving (or culminating in) biomarker dysregulation, and polypharmacy. These correlates are difficult to modify, especially through population health interventions. The second category, which contains fewer correlates, includes potentially modifiable public health targets, such as food-related properties, psychological, sociocultural, and environmental issues. We conclude that there are several AA correlates. Some of them are modifiable and could be targeted for development and implementation as appropriate population health interventions to prevent appetite loss and promote maintenance of adequate food intake in aging.

[Intestinal microbiota and ageing: A new intervention route?]

Intestinal microbiota (IM) has continued to be the subject in all types of studies and publications. More is known on its different components and functions, as well as the changes that take place in IM through the life cycle, and the role of the factors involved in these changes. The aim of this review is to update the relationship between IM and aging. The presentation in 4 sections: (i)main factors of the human ageing process, underlining those related with gut changes; (ii)conceptual meaning of words like microbiota and other related terms; (iii)to comment on the most current findings as regards the changes in IM that occur in the ageing process, whether arising from the physiology or from disease situations, or other factors (environment, diet, drugs, etc.), and the health-consequences of these changes, and (iv)possibilities of different active positive interventions, with emphasis on diet measures.

Characterisation of the faecal bacterial community in adult and elderly horses fed a high fibre, high oil or high starch diet using 454 pyrosequencing

Faecal samples were collected from seventeen animals, each fed three different diets (high fibre, high fibre with a starch rich supplement and high fibre with an oil rich supplement). DNA was extracted and the V1-V2 regions of 16SrDNA were 454-pyrosequenced to investigate the faecal microbiome of the horse. The effect of age was also considered by comparing mature (8 horses aged 5-12) versus elderly horses (9 horses aged 19-28). A reduction in diversity was found in the elderly horse group. Significant differences between diets were found at an OTU level (52 OTUs at corrected Q<0.1). The majority of differences found were related to the Firmucutes phylum (37) with some changes in Bacteroidetes (6), Proteobacteria (3), Actinobacteria (2) and Spirochaetes (1). For the forage only diet,with no added starch or oil, we found 30/2934 OTUs (accounting for 15.9% of sequences) present in all horses. However the core (i.e. present in all horses) associated with the oil rich supplemented diet was somewhat smaller (25/3029 OTUs, 10.3% ) and the core associated with the starch rich supplemented diet was even smaller (15/2884 OTUs, 5.4% ). The core associated with samples across all three diets was extremely small (6/5689 OTUs accounting for only 2.3% of sequences) and dominated by the order Clostridiales, with the most abundant family being Lachnospiraceae. In conclusion, forage based diets plus starch or oil rich complementary feeds were associated with differences in the faecal bacterial community compared with the forage alone. Further, as observed in people, ageing is associated with a reduction in bacterial diversity. However there was no change in the bacterial community structure in these healthy animals associated with age.

Ageing and the gut

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.

Anorexia, undernutrition, weight loss, sarcopenia, and cachexia of aging

During the period between 2000 and 2030, the number of persons older than 65 years is projected to grow from 550 to 937 million worldwide. Globally, this growth represents an increase from 6.9 to 12 %. Studies have found that 74.6 % of women and 67.4 % of men aged 65 years or older suffer from many clinical and subclinical syndromes and problems, including anorexia, undernutrition, weight loss, sarcopenia, and cachexia, which are often overlooked or managed inadequately. These issues are very common in the elder. The key clinical question is whether these changes in the elder are distinct entities or an interdependent continuum. In this article, we reviewed these issues of related basic, clinical knowledge. The purpose of this review is to enhance the recognition of anorexia, undernutrition, weight loss, sarcopenia, and cachexia.

[Comparison of clinical characteristics and outcomes between geriatric and non-geriatric patients in peptic ulcer bleeding]

BACKGROUND/AIMS

In geriatric patients with peptic ulcer, the use of NSAID and prevalence of chronic illness have been increased, but the Helicobacter pylori (H. pylori) infected portion decreased. The aim of this study was to evaluate the clinical characteristics and outcomes of geriatric patients (aged 65 or older) with peptic ulcer bleeding and compare with non-geriatric patients (less than 65 years old).

METHODS

We conducted a retrospective study of 88 patients with peptic ulcer bleeding treated with therapeutic endoscopy from January 2006 to December 2006. We compared the clinical characteristics and outcomes of geriatric patients (n=34, 38.6%) with those of non-geriatric patients (n=54, 61.4%).

RESULTS

Hypertension (52.9% vs. 24.1%), cardiovascular disease (35.3% vs. 13.0%), and chronic obstructive pulmonary disease (20.6% vs. 3.7%) were more prevalent in the geriatric group, compared with the non-geriatric group (p<0.05). The geriatric group had taken more ulcerogenic drugs than the non-geriatric group (64.7% vs. 33.3%, p<0.05); aspirin plus clopidogrel (23.6% vs. 13.0%) and aspirin (20.6% vs. 11.0%). Sixteen (21.1%) of the 76 cases had H. pylori-negative ulcer. Between the two groups, there was no difference in the prevalence of H. pylori-negative ulcer (25.9% vs. 18.4%, p>0.05). The amount of transfusion length of ICU stay, rebleeding rate, operation rate and mortality were not different between the two groups. The length of hospital stay in the geriatric patients was significantly longer than the non-geriatric group (12.3+/-10.6 vs. 7.2+/-5.9 days, p<0.05). In multiple regression analysis, old age was a significant risk factor for longer hospital stay (p<0.05).

CONCLUSIONS

The geriatric patients with bleeding peptic ulcer had longer hospital stay than the non-geriatric patients in our study. The important emerging etiologies such as ulcerogenic drug and associated chronic illness should be checked and treated in these patients.

The clinical significance of gastrointestinal changes with aging

PURPOSE OF REVIEW

With the graying of the world's population, there is an increased interest in the physiological effects of aging. This review examines the physiological changes of the gut with aging and their clinical significance.

RECENT FINDINGS

Changes with aging in the gastrointestinal tract are variable, but in some cases they are responsible for a variety of symptoms. Thus, alterations in taste and smell, gastric motility, intestinal overgrowth and changes in gastrointestinal hormone release are the basis of the physiological anorexia of aging. Alterations in swallowing lead to silent aspiration. Changes in gastric emptying play a role in postprandial hypotension. Changes in gastrointestinal function can lead to constipation and fecal incontinence. Weakening of the colonic muscular wall produces diverticula. Achlorhydria is associated with malabsorption of some forms of iron and calcium. Vitamin D malabsorption aggravates the hypovitaminosis D that is so common in older persons. Changes in probiotics can lead to diarrhea and altered immune system. In the liver, aging is associated with delayed drug metabolism.

SUMMARY

Changes in the physiology of the gut play a role in the anorexia of aging, aspiration pneumonia, postprandial hypotension, constipation and fecal incontinence.