Differences in Gut Microbiome Composition between Senior Orienteering Athletes and Community-Dwelling Older Adults

Abstract

Background: Gastrointestinal (GI) health is an important aspect of general health. Gastrointestinal symptoms are of specific importance for the elderly, an increasing group globally. Hence, promoting the elderly's health and especially gastrointestinal health is important. Gut microbiota can influence gastrointestinal health by modulation of the immune system and the gut-brain axis. Diverse gut microbiota have been shown to be beneficial; however, for the elderly, the gut microbiota is often less diverse. Nutrition and physical activity, in particular, are two components that have been suggested to influence composition or diversity.

Materials and methods: In this study, we compared gut microbiota between two groups of elderly individuals: community-dwelling older adults and physically active senior orienteering athletes, where the latter group has less gastrointestinal symptoms and a reported better well-being. With this approach, we explored if certain gut microbiota were related to healthy ageing. The participant data and faecal samples were collected from these two groups and the microbiota was whole-genome sequenced and taxonomically classified with MetaPhlAn.

Results: The physically active senior orienteers had a more homogeneous microbiota within the group and a higher abundance of Faecalibacterium prausnitzii compared to the community-dwelling older adults. Faecalibacterium prausnitzii has previously shown to have beneficial properties. Senior orienteers also had a lower abundance of Parasutterella excrementihominis and Bilophila unclassified, which have been associated with impaired GI health. We could not observe any difference between the groups in terms of Shannon diversity index. Interestingly, a subgroup of community-dwelling older adults showed an atypical microbiota profile as well as the parameters for gastrointestinal symptoms and well-being closer to senior orienteers.

Conclusions: Our results suggest specific composition characteristics of healthy microbiota in the elderly, and show that certain components of nutrition as well as psychological distress are not as tightly connected with composition or diversity variation in faecal microbiota samples.

Keywords: Faecalibacterium prausnitzii; aged; gut microbiota; metagenomics; orienteering.

Figure 1

Factors affecting the composition of gut microbiota.

Figure 2

Relative abundance of the 10 most abundant genera across 98 samples.

Figure 3

Relative abundance of significantly different genera and selected species stratified for group (senior orienteers compared to older adults). Cut-off for significance was set at false discovery rate (FDR) <5%. Descriptive p-values for each comparison are shown. (A) Genera; (B) Species.

Figure 4

Comparison of covariates. Boxplots of covariates stratified for older adults and senior orienteers, including descriptive p-values from Welch’s t-test. (A) Macronutrients measured by energy percentage (E%). (B) Fibre measured by grams per megajoule (MJ). (C) Hospital Anxiety and Depression Scale (HADS) score. (D) Bar plot for medication covariates for older adults and senior orienteers, including descriptive p-values from chi-square test.

Figure 5

Significance of difference between older adults and senior orienteers after correction for macronutrients, psychological distress, and medication variables. Corrected bacterial composition values were compared between groups for each species and false discovery rates (FDRs) calculated. The dots represent negative log10 p-values belonging to respective species, where blue denotes significance and red denotes non-significance, with a significance threshold at FDR <5%. A Results for models with a single macronutrient variable and with all macronutrient variables in a multi-variable model. B Results for models with single medication variables and with all variables in a multi-variable model. C Results for models regarding anxiety and depression separately with single Hospital Anxiety and Depression Scale (HADS) variables and with both HADS variables in a multi-variable model. D Results for models with sex and age.

Figure 6

Assessment of relative importance of all covariates. A complete model comprising all covariates for assessing variable importance. The relative importance of each covariate was measured as likelihood-ratio chi-square statistics.

Figure 7

Principal coordinates analysis (PCoA) plots. Principal coordinates were estimated using Bray–Curtis distance on the predicted species. Each dot represents an individual sample, shape depicts groups, and blue scale codes for the gastrointestinal symptom scores measured with Gastrointestinal Symptom Rating Scale (GSRS) values. Dotted ellipse indicates 95% confidence region of older adults and dashed ellipse indicates 95% confidence region of senior orienteers. CEA = 95% confidence ellipse area. (A) PCoA using all predicted species; (B) PCoA using four selected species that were significantly different between older adults and senior orienteers.

Figure 8

Comparison of covariates when older adults are stratified for typical and atypical. Atypical older adults are defined as samples outside of the confidence ellipse area in Figure 7. Statistically significant differences are marked with an asterisk. (A) Macronutrient intake measured by energy percentage (E%). (B) Fibre measured by grams per megajoule. (C) Anxiety and depression scores. (D) Mean score of gastrointestinal symptoms. (E) Representation of proportion of subjects with medications.

Figure 9

Correlation between Faecalibacterium prausnitzii and fibre intake. Shape depicts different groups. Dotted line, solid line, and dashed line represent regression lines for senior orienteers, typical older adults, and atypical older adults, respectively. Confidence interval (95%) values are given in brackets for respective observed correlations.