How is my gut actually doing? This question is more present than ever, because the microbiome of our intestine is becoming more and more conscious and is now held responsible for many mechanisms in our body. Whether we live to a ripe old age is determined by many factors over which we probably have more influence than previously assumed. The latest research indicates that the intestinal flora is significantly involved in how long we live and which diseases we will contract.
The role that intestinal health plays becomes clear when we take a look at social developments. One thing becomes very clear: the age structure of the population is increasing in the industrialised nations. For this reason, our need for new solutions to reduce age-related diseases is also growing. The treatment of chronic inflammation is in the foreground, because inflammatory processes can be detected in almost every age-related disease. The gut microbiome has long been underestimated in this context - but is now increasingly the subject of new research. That's what we're talking about now, let's go!
The microbiome: a super organ?
The term microbiome is used synonymously with intestinal flora and refers to the totality of microorganisms that colonise our intestines. These are mainly bacteria, the strains of which can be divided into four types. The composition of the intestinal flora can provide information about our physical condition. In other words, a healthy intestinal flora is not only responsible for good digestion. The intestine is therefore often described as a second brain that is able to influence our body, our emotions and the entire metabolism and immune system.
The intestinal immune system, called GALT (gut-associated lymphoid tissue), houses about 70 percent of our immune cells and helps eliminate unwanted germs and foreign substances. Through an intelligent system, it can distinguish between good and bad germs and thus manages to maintain healthy intestinal flora and fight harmful invaders.
Our intestines are interwoven with millions of nerve cells. This enables it to communicate directly with the brain and exchange information. So our second brain not only sends signals, but also receives them. But before we get too carried away, let's now turn to the most exciting part, namely how the gut can ensure longevity.
The microbiome of the very old
Only very few people live to a ripe old age and are still fit and healthy. The average lifespan in which we live healthily and without diagnoses and therapies is becoming shorter and shorter. But what is the secret of very old people? Although one's own fate cannot be completely influenced, it is nevertheless certain that we can have a positive effect through a healthy lifestyle with plenty of exercise and a healthy diet. For a long time, it was assumed that genetics played the biggest role in how old and healthy we are. But studies suggest that this influence is far less than thought, estimated at 15 to 30 per cent. Who would have thought it?!
In this context, our intestinal flora has also become the focus of attention. The importance of the numerous bacteria in the human body is becoming increasingly clear and can be divided according to their function. According to a study by Keio University in Japan, the health of very old people depends to a significant extent on the bacterial composition of the intestinal flora, which influences the immune system and the entire metabolism.
It is said that every human being is unique. The unnoticed meaning behind this saying is explained in the following paragraph. The colonisation of the intestinal flora is a lifelong process that begins at birth and ends only at death. In a study published inNature Metabolism, the intestinal flora of 9000 people in an age range of 18 to 101 years was compared. The researchers found that not only the human being itself ages, but also the microbiome of the intestine. In healthy subjects over 77 years of age, changes were observed in the intestinal flora, in which rare species of bacteria dominated and the usual microbiome pattern decreased. In less healthy subjects, this uniqueness was absent.
The fountain of youth in the gut
And now we turn to one of the most interesting questions in human history: Why do some people live to a ripe old age and some don't?
Let's take a look at the development in Japan, because nowhere else do more over-centenarians live. In cooperation with scientists from the USA, the answer to this question has now come a little closer. The scientists compared the intestinal microbiome of different age groups and found that the intestinal flora of people over 100 has a characteristic composition in which microorganisms that produce certain bile acids are found in large numbers. So far, the function of these microorganisms has not been fully clarified, but it is assumed that they are able to inhibit the growth of intestinal pathogens. For example, the researchers identified a molecule called isoalloCA, which can inhibit the growth of Clostridium diffizile. Clostridium diffizile is a typical hospital germ that causes severe diarrhoea and is also resistant to antibiotics. The researchers conclude that very old people have high levels of this protective molecule, which contributes to health and longevity.
But what good is old age if we are mentally wasting away and can no longer enjoy life to the full? Studies suggest that stool transplants could help keep the brain young. For this purpose, older mice underwent stool transplantation, donated by young mice. After four weeks, the first results appeared: Indeed, some age-related cognitive impairments were attenuated by the donor microbiota in the old mice. But before we get too euphoric, we should postpone our hopes until the time when human studies can show similar results.
The microbiome in balance
We have learned that the composition of our intestinal flora is important. But many causes cause the balance to get out of sync, such as antibiotic therapy, or a poor diet. Our organism depends on this complex system and benefits from this nutrient-rich environment. A dysbiosis of the intestinal flora can have serious consequences and promote infections and inflammatory processes. To a certain extent, the intestinal flora has the power to counteract harmful factors and prevent disease processes. Once the microbiome is out of sync, it also has the ability to return to "normal" afterwards. However, if the harmful factors persist, they can be the reason for the development of diseases. A balanced diet, rich in fiber, is the basic requirement for healthy intestinal flora. Probiotics have a health-promoting effect on the intestinal flora and can help to strengthen the barrier function of the intestine.
Last but not least
"...a sick intestine is the root of all evil...", Hippocrates already knew. An intact intestine is extremely important for our health and a long life. Understanding the molecular composition is a challenge we now have to meet. More research is needed to better understand the complex interactions.
Until then: Be good to your bowels!
Sato, Yuko, et al. "Novel bile acid biosynthetic pathways are enriched in the microbiome of centenarians." Nature (2021): 1-7.
Ruby, J. Graham, et al. "Estimates of the heritability of human longevity are substantially inflated due to assortative mating." Genetics 210.3 (2018): 1109-1124.
Wilmanski, Tomasz, et al. "Gut microbiome pattern reflects healthy ageing and predicts survival in humans." Nature metabolism 3.2 (2021): 274-286.
Boehme, Marcus, et al. "Microbiota from young mice counteracts selective age-associated behavioral deficits." Nature Aging 1.8 (2021): 666-676.
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