Nursing Home Living Reshapes the Aging Gut, and Diet May Be the Lever to Fix It

Why it matters: The global population aged 60 and over is projected to reach 2.1 billion by 2050, which will increase demand for long-term care. Gut dysbiosis is now proposed as a hallmark of aging, yet the microbiome of nursing-home residents is understudied. These residents combine frailty, immunosenescence, multimorbidity, polypharmacy and a high risk of undernutrition, all of which can affect gut ecology.

What was reviewed: This narrative review brings together geriatric, nutritional and microbiome literature on institutionalized older adults. The available text covers the aging gut microbiome, the effect of place of residence, age-related physiological changes affecting nutrition, and early diet–microbiota evidence in nursing homes. According to the abstract, the review also covers immune decline, infection risk, sarcopenia, cognitive deterioration and medication burden, and then proposes interventions.

Key findings: Aging is typically linked to lower microbial diversity, greater interindividual variability, fewer short-chain fatty acid producers (Faecalibacterium prausnitzii, Eubacterium, Bifidobacterium), and more Enterobacteriaceae and other potentially harmful groups. Healthy centenarians often have more diverse microbiomes enriched in Christensenellaceae, Akkermansia and Bifidobacterium, and beneficial metabolites such as indolepropionate have been tied to longevity. In the ELDERMET work cited (Claesson et al.), nursing-home residents had less diverse microbiota than community dwellers, and this was associated with greater frailty, lower muscle mass and poorer health. Length of stay matters. Dysbiosis, including early rises in Enterococcus faecalis, Klebsiella pneumoniae and Haemophilus parainfluenzae, appears in the first 6–12 months. Frailty-related microbiome changes accrue over about 18 months, and residents with lower baseline diversity shift most. Afterward, the microbiome may settle into a more stable state.

Diet is a central driver. Age-related loss of taste and smell, tooth loss, dysphagia, reduced digestive enzymes, slower transit and hormonal changes in appetite all alter intake. Malnutrition prevalence in care facilities is reported at 1.5% to 66.5%. Over half of new residents have a BMI under 23 kg/m², while obesity among US residents rose from 22% to 28% between 2005 and 2015. Nursing-home diets tend to be low in fiber and are associated with more Proteobacteria and Clostridia and fewer Lactobacillus and Bifidobacterium.

Implications: Because diet, activity and medication practices in institutions are modifiable, the authors propose multimodal, microbiota-informed care. This includes individualized dietary adaptation, targeted supplementation, physical activity programs, and digital and AI tools for personalized nutrition. They also call for standardized protocols and implementation-science frameworks to support clinical translation.

Caveats: This is a narrative review, and the authors acknowledge that the institutionalized-elderly microbiome is understudied. Much of the evidence is observational, so residence, diet, frailty and medication use are hard to separate causally. The text provided here ends partway through the diet–microbiota section, so the intervention details rest largely on the abstract.