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avje starostnikov | health of the elderly 192 disorders. Nutritional strategies aiming at microbiota and immune
modulation in the elderly are especially relevant due to their higher
susceptibility to disease, malnutrition, impairment of the gut microbiota
and a pro-inflammatory status of the immune system. Animal studies
show that interventions with antibiotics, microbial infections, prebiotics,
probiotics and faecal microbiota transplantation not only affect gut
microbiota composition, but also influence cognitive impairment related
to AD. Analysis of the gut microbiota and its potential for modulation
to improve health are important elements in the process of improving
health of the elderly. Discussion and conclusions: Nutritional strategies
for the elderly should consider the nutritional deficiencies and needs,
but also the gut microbiota, the immune system and cognitive function.
More research is needed to better understand the changes in gut
microbiota over the lifespan and associated pathologies.
Keywords: gut microbiota, aging, elderly, intestine, nutrition

Introduction
The human gastrointestinal tract contains more than 1012 of microorganisms
per millilitre and represents the biggest microbial community in the human
body. Gut bacteria are key regulators of extraction, synthesis and absorption
of many nutrients and metabolites, such as bile acids, lipids, amino acids, vita-
mins and short-chain fatty acids (SCFA) (Rinninella et al., 2019). Gut microbio-
ta can affect distant organs by regulating the absorption of nutrients or the pro-
duction of microbial metabolites such as SCFA or vitamins, by regulating the
immune system and by translocating bacteria or their products through dis-
rupted mucosal barriers (Shimizu, 2018). For the last two centuries the lifespan
has been increasing by two years per decade in the developed countries (Sala-
zar et al., 2017). Most western countries have experienced a significant increase
in the proportion of elderly citizens (65 years and older) due to improved sani-
tation, hygiene and healthcare (O’Toole and Jeffery, 2015). One of the most rec-
ognized effects of aging is the age-associated immune deregulation (Salazar et
al., 2017). Gut dysbiosis can trigger the innate immune response and chronic
low-grade inflammation, leading to many age-related degenerative pathologies
and unhealthy aging (Kim and Jazwinski, 2018). An adequate nutritional sta-
tus is important to maintain the functionality of the immune system and pre-
venting frailty and cognitive function in the elderly (Salazar et al., 2017). Analy-
sis of the gut microbiota and its potential for modulation to improve health are
important elements in the process of improving health of the elderly (O’Toole
and Jeffery, 2015).

Methods
We performed a literature search accessing the databases PubMed, Google-
Scholar and ScienceDirect using following keywords and their combinations:
»gut microbiota«, »gut microbiome«, »elderly«, »longevity«, »Alzheimer’s dis-
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