Over the last decade, the proportion of the developed world’s population over the age of 65 years has increased by more than 10%. Furthermore, it is projected to increase over 20% by 2030. Life expectancy continues to increase globally and is expected to reach the mid-70s by 2050. Maintaining health in older age depends on the appropriate function of the homeostatic systems (nervous, endocrine and immune) and correct interactions between these systems and gut microbiota. However, these systems undergo modifications in elderly persons, thus accounting for a reduction in the functional capacity of all the organs in the body, which, in turn, may evolve toward “inflammaging”, a phenomenon characterized by a low-grade inflammatory state, involved in the aetiology of several age-related chronic pathological conditions. Physiological declines in immune function are termed “immunosenescence”, which may lead to the impairment in both cellular and adaptive immunity, together with age-related oxidative stress, a low-grade inflammatory state, and intestinal dysbiosis. Overall, immunosenescence may be linked to a perturbed gut microbiota and frailty in the elderly.
Gut immune response and microbiota composition are impaired in elderly. In older adults there seems to be a decline in microbiota diversity, with lower numbers of Firmicutes and bifidobacteria and an increase in Bacteroidetes and certain Proteobacteria (which are thought to play a role in bowel disease). However, it is not yet clear how these changes are a result of the senescence of the immune system or altered dietary intake or physical activity. Despite the fact that ageing has a significant effect on the microbiota, its alterations can be consequent to conditions that occur frequently in the elderly, such as the decline of the general state of health with malnutrition and with increased need for medication. Thus, a causal relationship cannot yet be assumed between aging and gut microbiota changes.
There is therefore a growing awareness about the role of probiotics in modulating the gut microbiota to maintain health in the elderly. Clinical trials that have assessed their effectiveness in ageing populations are scarce, but may show that health benefits can be achieved through: 1) Their effect on the composition of the microbiota in elderly populations; and 2) Their effect on the symptoms of major gastrointestinal diseases. Probiotics with Bifidobacterium and Lactobacillus genera are among the most studied in clinical trials with elderly populations. They may restore a healthy microbiota and control oxidation and inflammatory processes, which can be beneficial in ameliorating immunosenescence, the risk of infections, and nervous system impairments in older adults.
In conclusion, probiotics may have a particular application in elderly populations, especially in terms of protection against infections and perhaps also in the prevention of several age-related diseases. Further studies with a double-blind, placebo-controlled design should be performed for a better assessment of probiotics’ potential to maintain a beneficial microbial balance to promote health in the elderly.
These findings were reviewed in a talk by Dr. Mónica de la Fuente, a researcher from the Faculty of Biology at Complutense University of Madrid during the 7th edition of the latest Spanish Society of Probiotics and Prebiotics (SEPyP)’s annual workshop, which was held on Seville (Spain) on January, 28-29th under the theme: “Probiotics, Prebiotics and Health: Scientific Evidence”.
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