Few people grow old and live to be over 100 years old. They are often still fit and healthy, while others suffer from chronic diseases decades earlier. What’s your secret? What is certain is that this fate is not entirely in your own hands, even if a lifestyle with little stress, a happy social life, a healthy diet and a lot of exercise is certainly helpful.
But whether you live long also depends on the genetic make-up. The genetic influence is possibly much less than expected. So one came study three years ago to the conclusion that the lifespan is less than ten percent predetermined by the genes; not 20 to 30 percent, which was previously the common doctrine. Other popular declarations such as so-called Longevity Islands – in other words, places where a particularly large number of extremely old people live, e.g. Sardinia or Okinawa in Japan – are rather controversial in age research.
The microbiome is also aging
In the search for new answers to the great differences in life expectancy, the microbiome has recently become the focus of attention. It is becoming increasingly clear how important the countless bacteria in and on the human body – e.g. in the intestines, in the mouth and on the skin – are for disease protection and health. They could also play a key role in aging.
Like the researchers around Yuko Sato from the Japanese Keio University in their just published in “Nature” study write that the state of health of older people depends, among other things, on changes in intestinal bacteria. The metabolism, bone health, immune defense and neurological functions are influenced by this.
How much colonization of the intestine changes in the course of life is shown by a publication published this year in the specialist magazine “Nature Metabolism” study. To do this, the microbiome of 9,000 people between 18 and 101 years of age was compared. The researchers found, among other things, that in healthy people who are over 77 years old, bacteria that were previously common are fewer, whereas rare species become more. This creates more anti-inflammatory metabolic products.
Accumulation of useful germs
Yuko Sato’s group has now come across a similar connection. She analyzed stool samples from Japanese: 47 young people (21 to 55 years old), 112 older people (85 to 89 years old) and 160 over-centenarians, in Japan there is generally an above-average number of very old people.
In the intestines of the centenarians, some types of bacteria were found much more frequently than in the younger ones. These microbes are involved in the formation of secondary bile acids in the intestine. According to the researchers, the acids are in turn important for various biological processes, such as metabolism and the immune system. Experiments in the laboratory and with mice confirmed the strong antimicrobial effect against common pathogens, such as those that cause diarrhea.
The accumulation of beneficial bacteria could have something to do with genes, but also with lifestyle or diet, the authors write. In the future, the health-promoting effects of such microbes may possibly also be used therapeutically.