Aging well? It relies also on gut bacteria

Article by Solongevity Research

The gut ecosystem in aging

This complex ecosystem is becoming increasingly important and recent research has linked it to the aging process. We know that our gut microbes, can influence the way we age. Understanding the microbiota  The first attempts to observe the microbiota date back to the second half of the seventeenth century, however, only recently it became the focus of research follwing the development of metagenomic techniques.

Metagenomics is the branch of science that analyses all the genetic material present in a given environment.

This is the branch of science that analyses all the genetic material active in a given organic environment. The human metagenome, for example, consists of the genetic material of the human being and that coming from bacteria, fungi and viruses that crowd our organism. ‍ The true qualitative leap in the study of the human microbiota, however, is due to the mapping of bacterial strains on the basis of 16S ribosomal Rna sequences, molecules typical of bacteria and not present in human cells. From the skin to the urogenital system, our body is teeming with microorganisms. And the intestines are no exception. The intestinal microbiota, in fact, is fundamental to our health at any age. It produces vitamins and amino acids essential for our body and is able to activate bile acids. It also metabolizes polysaccharides of vegetable origin (i.e. fiber) and supports the absorption of fats (lipids) by the intestine. Microbiota and Ageing The composition of the microbiota – unique for each individual – is influenced by many factors, such as diet and exercise. But age also counts: as time goes by, it undergoes alterations that are sometimes such as to cause real gastrointestinal pathologies.

Intestines’ microbial biodiversity decreases with advancing age. What decreases are the bacterial species that produce short-chain fatty acids, known to regulate one of the mechanisms of aging and the immune response.

The most common changes in the microbiota over time have been shown through cohort studies comparing the intestinal flora of adult individuals with that of older people. This comparison showed how microbial biodiversity, on average, decreases with advancing age. In particular, it is the bacterial species that produce short-chain fatty acids (ScFA), such as acetate and butyrate, that decrease. ScFAs, however, are known to regulate one of the molecular mechanisms underlying aging (the mTor signaling pathway) and to modulate the immune response by inhibiting inflammation mediators.
The intestinal microbiota is fundamental for our health at any age. It produces vitamins and amino acids essential for our body and is able to activate bile acids. It also metabolizes polysaccharides of vegetable origin (i.e. fibers) and supports the absorption of fats (lipids) by the intestine.
It is possible, therefore, that this explains why the intestines – and the body in general – of the elderly are more fragile. In the last 10 years, moreover, it has been shown that intestinal flora is linked to the formation of the blood-brain barrier and to myelination and neurogenesis processes, suggesting that an alteration of the intestinal microbiota may predispose to the development of neurodegenerative diseases. Studies on the bacterial flora of centenarians and those, who suffer from conditions such as diabetes and obesity, suggest that there are “good” and “bad” bacteria. ‍ On the other hand, the analysis of the centenarian microbiota has reserved some surprises. The intestinal flora profile of people living over 100 years is unique and is characterized by the presence of species such as Akkermansia, Christensenellaceae and Bifidobacterium. This evidence, combined with studies comparing the intestinal microbiota of healthy individuals with that of people suffering from diseases such as diabetes and obesity, suggests that there are good and bad microbial species. Here, however, an explanation is necessary: there are no good and bad bacterial species at all, but the goodness of a bacterial strain depends more on its balance in the intestinal ecosystem. If a bacterium proliferates too much at the expense of other species, it becomes bad. Ageing less, ageing better how we live potentially affects the intestinal microbiota, diet first and foremost. With age, therefore, maintaining the diversity of bacterial strains becomes increasingly important, so that we age more slowly and better.  But how? Microbes are sensitive to the environment, such as the stimuli coming from the host organism. Therefore, everything we do has a potential impact on the intestinal microbiota, diet first and foremost. Today we have the possibility to monitor the microbiota thanks to tests on faecal samples that give us useful information for planning a personalized nutritional plan . ‍ due to everyone’s microbiota uniqueness, there is no diet that is good for everyone. The general rule is to follow a varied diet, which includes both animal and vegetable derived foods, helps to increase microbial biodiversity in the intestine. However, today we have the possibility to monitor the microbiota thanks to tests on faecal samples that give us useful information for the management of a personalized diet.
the analysis of the centenarian microbiota has come as a surprise. The profile of the intestinal flora of people living over 100 years is unique and is characterized by the presence of species such as Akkermansia, Christensenellaceae and Bifidobacterium.
Probiotics, prebiotics and symbiotics can also help. Probiotics are foods that contain good bacterial strains that can reach our intestines alive and colonize them. Prebiotics, on the other hand, are undigestible substances such as water-soluble fibres, which reach the intestinal tract and feed the bacteria. The process by which bacteria break down the fibres is called fermentation and its waste products are actually useful to our organism.  Finally, compounds that contain both probiotics and prebiotics are called symbiotics. Although further studies are needed, the data suggest that these small intestinal microbiota modulation interventions, when taken under medical supervision and criteria, may be effective on overall health, reducing inflammation and improving immune system function. Finally, keeping active and well integrated into the social environment would also have a weight. The biodiversity of the intestinal microbiota in the elderly, in fact, appears to decrease in contexts of greater isolation.

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