For some years now, the microbiome increasingly becoming the focus of public interest. billions of bacteria, The microbes living in our bodies have a previously underestimated influence on whether we are healthy or ill. The exact connections are not yet fully understood, but one thing is certain: We live in a close Symbiosis with our bacteria.
The better we understand this interplay, the better we can utilize it. Do we eat a lot? z.B. plant fiber Can our gut bacteria convert these into short-chain fatty acids converting these substances, which are associated with several health benefits. Maintaining the greatest possible diversity in the microbiome is also beneficial to health.
What is meant by dysbiosis?
With age, this symbiosis seems to increasingly become a Dysbiosis to become. Fewer and fewer of the "good" bacteria live in our intestines, and the "bad" ones are gaining the upper hand. This cannot be easily reduced to a single type of bacteria, as each microbiome is highly individual and depends on many factors (e.g., ethnicity, living conditions, diet, lifestyle, etc.). Changes in the microbiome are associated with several chronic diseases, such as... Diabetes, cardiovascular diseases and cancerHere you can find everything you need to know about this topic.
Our microbiome - more than just bacteria
About the microbiome Entire books could be written on the subject. Hardly a day goes by without a new study being published. And the research interest is more than justified. The microbiome depends on us, and vice versa. Exactly how this symbiosis works is gradually being revealed. In very broad terms, we need the microbiome to access some nutrients from food.Our bodies don't possess the right enzymes to break down every nutrient. And that's precisely where the microbiome comes into play.
What would normally be considered "waste" by us, how z.B. Dietary fiberIt can be digested by our microbiome. The bacteria even depend on us to "feed" them. In return, they produce several substances that are beneficial to our health. These include secondary bile acids, vitamins, amino acid derivatives and short-chain fatty acids.
Furthermore, the microbiome appears to be closely related to our Intestinal nervous system – A gigantic network of nerve cells that surrounds our intestines along their entire length. If you will, our second brain or our "gut feeling"“And this enteric nervous system is of course also in communication with our central nervous system.”
As you can see, the microbiome is complex, and its interconnections and effects are even more so. This doesn't always make it easy to conduct studies. Nevertheless, scientists have been able to discover quite a bit about aging. More on that in a moment.
Symbiosis instead of dysbiosis - What is a healthy microbiome?
Before we look at what happens when the microbiome doesn't work to our advantage, we need to ask ourselves what a microbiome actually is. A healthy microbiome isThis question is more difficult to answer than it might initially seem. There are countless studies on the subject, and the findings can be defined as follows: The microbiome is highly individual. What bacteria did we pick up in early childhood? In which country were we born? What genes do we carry? What did our diet look like in childhood? Did we have any severe intestinal infections? What is our diet like? Do we eat a lot of fiber? And so on.
It is widely recognized, that we develop our microbiome in early childhood and that it usually remains stable throughout our adulthood remains (unless one radically changes one's lifestyle or environment).
The older we get, the more the diversity of bacteria in our gut decreases. Researchers see this as one of the main reasons for age-related diseases. A one-sided microbiome makes us susceptible to an overgrowth of "bad" bacteria.
This can be impressively illustrated by the example of Clostridium difficile see. This tiny bacterium lives in our intestines and initially doesn't cause much of a stir. If we have a more severe infection, which requires specific antibiotic treatment, However, this bacterium has a survival advantage.While most of the bacteria in our gut die, some survive. C.difficile and begins to multiply rapidly, as suddenly there are no competitors left. The result is a severe intestinal infection that often requires hospital treatment.
Dysbiosis can z.B...caused by an overpopulation of the bacterium Clostridium difficile. This is often due to antibiotic therapy.
Dysbiosis using p-cresol as an example
There are hundreds of metabolic processes, all of which have a potential impact on our health. To simplify things a bit, we'll show you an example of a fairly well-researched metabolite: p-Cresol
In the ELDERMET study Five hundred people, all over 65, were tested for their microbiome and potential metabolic products. The results showed that participants with higher stool concentrations of p-cresol exhibited increased frailty.
What is p-cresol? This molecule is created by the Fermentation of the amino acid tyrosine in our intestine. The sulfated version of the molecule is excreted via our kidneys. As long as our kidneys are healthy, this doesn't seem to be a problem. However, if the filtration rate decreases and the p-cresol level in our blood rises, it appears to become problematic.
High p-cresol levels are associated with the development of cardiovascular diseases and are toxic to the filtering system in our kidneys. This seems to be a vicious cycle. People with impaired kidney function often have a Dysbiosis of the microbiome.There is an increased presence of aerobic bacteria that promote the production of toxic metabolites, including p-cresol. This may hold a potential starting point for future research.
Tryptophan metabolism: From symbiosis to dysbiosis
Another important metabolic process in our intestines is the Tryptophan pathway. Tryptophan is an amino acid that we z.BWe absorb it through food. Our gut bacteria have various ways of metabolizing this amino acid. We'll show you the three most important ones:
- Kynurenine Way (Kyn): About the enzyme I DO (Indoleamine 2,3-dioxygenase) breaks down tryptophan to kynurenine.
- Serotonin pathway: Our gut bacteria can convert tryptophan into the "happiness hormone" serotonin. A full 90% of our serotonin is located in the gut! Tryptophan can also be transported via this axis into Melatonin, the sleep hormone, are converted
- Indole WayThe third pathway for tryptophan degradation is the indole pathway. Higher indole concentrations in older people have been associated with a increased fitness This has been linked to [the following]. In mice, an increase in indole metabolites was also shown to increase lifespan.
Dysbiosis as a hallmark of aging: Balance is key.
Some studies regarding tryptophan metabolism conclude that a Disruption of the balance can contribute to illnesses. Is z.B. the aforementioned enzyme IDO (to be precise, the subclass IDO-1) is over-enabled, We find more kynurenine compared to serotonin in the body than is normal. This excess kynurenine is associated with several diseases. For example, it has been shown that Depressed individuals often have an overactivation of IDO-1, resulting in lower serotonin levels. One hypothesis is that this contributes to depression.
Note: The long-held hypothesis in science that low serotonin levels are the trigger for depression is not entirely correct. Serotonin plays a role in the disease, but it cannot be broken down so easily.
Chronic inflammation can increase IDO activity. and thus the assumption can be formulated that Inflammation This can also contribute to the dysbiosis of our microbiome.
Inflammaging and dysbiosis – two hallmarks closely linked
As we just saw, a Chronic inflammation can negatively affect our microbiomeHowever, it also seems to work the other way around, at least according to experiments on mice. Two populations of mice were used for this purpose: one of young and healthy mice and one of older, sick mice. The microbiome of the older mice was then transferred to the younger mice..The result was that the younger mice showed significantly more signs of inflammation, i.e., higher inflammatory markers.
Conclusion
The microbiome is one of the most exciting fields of research, and the disruption of its balance seems to contribute to some diseases in old age. We are losing the diversity of bacteria that keep us healthy, and that is why dysbiosis has been included as one of the hallmarks of aging.In the future, we will certainly see some therapeutic approaches that will reverse this dysbiosis.
The next article in this series will discuss the twelfth sign of aging: Altered autophagy.
