Healthy aging is a process we all would like to pass through without enduring all the complications associated with our body as it gets older. For our sakes, we are keen to minimise trips to the hospital and ward off illness as best we can. If we can find ways and means to extend life or at least reduce the vicissitudes of old age then we’ll grasp at them.
In this article we examine how our gut microbiota changes as we age naturally. Incidentally, microbiota refers to all the bacteria, yeasts and fungi which live in our guts. What does it mean for example to this important bacterial population that inhabits our space when we change our diet or where we end up living. There is evidence that our microbiota changes when we have to have extended stays in hospital – an increasing occurrence for the elderly (O’Toole and Claesson, 2010).
Before We Start: What Gut Microorganisms Are We Interested In !
When we discuss microorganisms, we have lots of different genii to refer to. I’ll list them here because I’ll refer to them as we progress through the article. The ones of most interest and discussed in gut microbiota circles are:-
Alistipes, Bacteriodes, Blautia, Clostridium, Coprococcus, Eubacterium, Faecalibacterium, Lachnospira, Oscillospira, Parabacteriodes, Prevotella, Ruminococcus and Roseburia.
Some are still unclassified and being discovered as we sit here whilst others are so small in number they don’t get a mention yet.
The General Effect Of Aging
Older people will have a tendency to be more at risk from a host of hazards. All of us have to deal at some time in our lives with diseases, infectious or otherwise, and we are usually treated with antibiotics to clear them up. We also seem as we get older to have to deal with chronic conditions such as inflammation and obesity. The infection itself and the treatment have quite a dramatic impact on our gut microbiota. As we get older, the incidences of these two impacts has a tendency to rise let alone us having to deal with a number of specific issues related to our gut health.
A research group at the MRC’s Department of Molecular and Cellular Pathology in the University of Dundee, Scotland looked at how our gut microbiota changes as we age. Firstly, the gut flora and fauna changes as we age and not the better ! The composition and make-up of the microflora and fauna in the gut becomes less and less protective. We see an overall loss of diversity in our microbes Beneficial microorganisms like Lactobacillus and Bifidobacteria which are prevalent as children simply start disappearing as we get older (Hopkins et al., 2001). Meanwhile less benign bacteria such as the Enterobacteriaceae or Gram-negative bacteria which includes the group called Bacteriodes simply remain the same in number or actually rise as we age.
As children we can expect to have about 10 to the log10 counts of viable total anaerobes which include a similar number of Bifidobacteria and Bacteriodes and about 6 to the log 10 of Lactobacillus. This is the typical healthy situation for our gut microbiota.
The loss of benign bacteria is quite significant when we reach 67 years of age and above. The total number of anaerobes and the Bacteriodes in particular might remain the same or just increase. Meanwhile, the number of Bifidobacteria drops to 7 to the log10 viable count and the Lactobacillus drop to 5.5 to the log10.
The Effect Of Where We Live And The Implications For The Elderly As We Move Into Residential Care
Where you live and how long you must stay in hospital also changes the type of microbiota in your gut. A large team based in various institutions in University College Cork in Ireland , the food organisation Teagasc and numerous hospitals worked together to understand how our gut bacteria changed with where people were living. Principal Component Analysis (PCA) which you might encounter in sensory science for example was used to show how clusters of gut microbiota are distributed when we move from one environment to another (Claesson et al., 2012).
It’s possible to see a distinct progression in species from people who have very brief stays in hospital, through to rehabilitation and then to long-term visits to hospital or residential care. In that study microbiota composition could be separated to such an extent that there was a significant correlation with ‘measures of frailty, co-morbidity, nutritional status, markers of inflammation and with metabolites in faecal water’.
The young for example served as a control in that study and had similar microbiota to those in the community. None of them had the microbiota of those who had been in residential care for some time. That study also showed similar findings to the Dundee study. The diversity of microbiota of people in long-term care significantly dropped compared to those living in the community. That loss of community-associated microbiota correlated with increased frailty. It implies then that as we age, from a gut microbiota view point, we are better off being exposed to the general milieu of diverse peoples than being house bound or restricted in our exposure.
Diet – Community Effects Versus Long-Term Stay
When you examine the quality of the diet i.e. the healthy one and the less healthy one in community dwellers, and compare it with those in a long stay home such as residential care, it’s not surprising to see differences in that diet (Jeffrey et al., 2016). A healthy or less healthy diet is still just under 50% vegetables and fruit including fruit juices. The differences in healthiness mean slightly more brown then white bread, more unrefined cereals, marginally less meat and lower fat contents as the diet gets healthier. The amount of dessert and sweets remains a significant portion for all although a less healthy diet sees a marginal increase in sugary substances.
When we have to stay for some time in care, the diet changes quite radically. For the elderly this has quite major implications. It is also surprising that such a diet is much worse for our gut microbiota than even what is described as an unhealthy diet This diet is distinguished from the others by being known as the long-stay like diet (LS- Like). In the LS-Like diet, the amount of sugar and sweet stuff in the diet rises significantly as does high fat foods. We end up eating less fruit and vegetables. The implication is that we are not enjoying the healthy diet of our community dwellers. The other implication is that all those different bacteria alter with that diet. In the healthy diet we have lost of unclassified bacteria and a balanced set of all the representatives from different species. In the less healthy diet, the number of unclassified bacteria drops to almost a third that level whilst the Enterobacteria like Bacteroides rise significantly. In the Long-stay diet we also see a rise in the Alistipes numbers which suggests less benign bacteria are rising and the diverse range of good bacteria is dropping away. This situation is most significant for those in residential care because even a mildly less healthy diet seems better for you than the long-stay diet.
Are there ways round it for the elderly ? Of course. Whilst only three articles have been examined, it would be worthwhile increasing their exposure to a greater range of foods, increasing the variety and returning to what would be described by nutritionists as a healthy diet. Improving exposure to the general community would also be a benefit which means reducing the length of long-term stay. It isn’t possible for everybody but the evidence suggests the elderly’s gut microbiota would certainly benefit. It also means supplementing the diet with certain foods like probiotics and prebiotics to increase the range and number of healthy bacteria like Lactobacillus and Bifidobacteria.
References
Claesson, M. J., Jeffery, I. B., Conde, S., Power, S. E., O’connor, E. M., Cusack, S., … & Fitzgerald, G. F. (2012). Gut microbiota composition correlates with diet and health in the elderly. Nature, 492(7427), pp. 178 – 184 http://doi:10.1038/nature11319
Jeffery, I. B., Lynch, D. B., & O’Toole, P. W. (2016). Composition and temporal stability of the gut microbiota in older persons. The ISME Journal, 10(1), pp. 170-182
Hopkins, M.J., Sharp, R., Macfarlane, G.T. (2001) Age and disease related changes in intestinal bacterial populations assessed by cell culture, 16S rRNA abundance, and community cellular fatty acid profiles. British Medical Journal 48(2) pp. 198-205 http://dx.doi.org/10.1136/gut.48.2.198
O’Toole, P. W. & Claesson, M. J. (2010) Gut microbiota: changes throughout the lifespan from infancy to elderly. Int. Dairy J. 20, pp. 281–291
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