Microbial Targets for the Development of Functional Foods Accordingly with Nutritional and Immune Parameters Altered in the Elderly

Abstract

The results obtained in this study suggest potential targets for the development of functional foods for the elderly population.

Nutrition and the gut microbiome in the elderly

“…21 Similarly, variable results have also been observed for lactobacilli, with some studies reporting a reduction 22,28 and others an increase in the levels of these microorganisms at older ages. 24,27,29 It is still unclear whether this variability in the results obtained for certain microbial groups is related to actual population differences or to methodological issues, such as the different techniques used for determining microbial abundancies ( Table 1).…”

“…This is especially relevant in this human population since aging is related with dietary changes and a subsequent increase in the risk of malnutrition, as well as, with changes in the immune system. 24,33,34 All these alterations considered together, may explain the higher susceptibility of elderly people to disease. Besides, differences among elderly from different geographical locations have been also observed.…”

“…The levels of short chain fatty acids (SCFA), the main bacterial metabolites in the colon, are lower in elderly and the ratios among the different fecal SCFA also vary with respect to healthy younger adults. 20,24 These changes in the production of bacterial metabolites have been suggested to be related with variations in the colonic bacterial metabolism, which shifts from the predominantly saccharolytic metabolism normally observed in adults toward a predominantly putrefactive metabolism. 30 It is important to highlight that a change in the gut microbiota may not necessarily mean a detrimental health effect.…”

“…[19][20][21] The gut microbiota of elderly subjects is characterized by a reduced bacterial diversity, shifts in the dominant species, a decline in beneficial microorganisms, increase of facultative anaerobic bacteria and a decrease in the availability of total short chain fatty acids. 11 More specifically, when comparing the microbiota of elderly with that of younger adults, lower levels of Firmicutes, mainly Clostridium cluster XIVa and Faecalibacterium prausnitzii, and Actinobacteria (mainly bifidobacteria), and increased populations of Proteobacteria have been found [19][20][21][22][23][24] (Table 1). With regard to other relevant intestinal microbial populations such as the phylum Bacteriodetes, the results are more variable, with some studies reporting lower levels 19,[23][24][25][26][27] while others have indicated increases of this microbial group in elderly subjects.…”

“…11 More specifically, when comparing the microbiota of elderly with that of younger adults, lower levels of Firmicutes, mainly Clostridium cluster XIVa and Faecalibacterium prausnitzii, and Actinobacteria (mainly bifidobacteria), and increased populations of Proteobacteria have been found [19][20][21][22][23][24] (Table 1). With regard to other relevant intestinal microbial populations such as the phylum Bacteriodetes, the results are more variable, with some studies reporting lower levels 19,[23][24][25][26][27] while others have indicated increases of this microbial group in elderly subjects. 21 Similarly, variable results have also been observed for lactobacilli, with some studies reporting a reduction 22,28 and others an increase in the levels of these microorganisms at older ages.…”