It is rare for humans to live past 100 years. Recent research suggests that centenarians may have their gut microbiomes at least partially to thank for this feat.Study of Japanese people over 100 years old revealed that they have distinct types of bacteria in their stomachs. These compounds can be used to combat infections and other environmental stresses.In general, centenarians are less likely to develop age-related chronic illnesses and can prevent the spread of infectious diseases. It seems that the gut microbiome, the billions upon billions of microorganisms in our digestive tract, could be the reason.It is easy to believe that genes are the key to long-term health. However, genetics is only 30 percent of longevity. This leaves many other factors open, such as diet, relationships and, perhaps, gut bacteria.The study involved 160 centenarians across Japan, who had an average age of just 107 years. It also compared the bacteria found in their stool samples to the gut bugs from 112 older people in their 80s and 47 younger people.Researchers led by Yuko Sato, a microbiologist from Keio University School of Medicine, Tokyo, looked for differences in the microbiomes of the subjects, that is, in the types of bacteria they have and the kinds of compounds they produce.Studies of centenarians in Sardinia, Italy have shown that older people had more core microbiota species in their intestines then young people or the elderly.It is tempting to study the microbiome of your gut. Scientists might be able, by understanding what a healthy one looks and how to change them to improve your health or prevent future disease.Although it sounds appealing, the gut microbiome can be a complex and sensitive beast. Research has shown that diet changes can quickly alter the composition of gut microbes, promoting particular species or reducing others.Centenarians, however, are an extreme example for healthy aging. They must be doing something right in order to live so many years.The Japanese researchers note that while some centenarians showed signs of aging such as low levels of inflammation, the majority of them were healthy.While the total bile acid load of each group was similar, centenarians had a unique mixture of bile acids thanks to a few bacterial strains that can synthesize them.Further inspection revealed that one group of bugs was Odoribacteraceae strains. These produced a type bile acid known as isoallo-lithocholic acids (isoalloLCA).Researchers write that "Notably, both the fecal acid profile of centenarians and [microbial] community kind of centenarians were generally stabilised between longitudinal samples." These longitudinal samples were collected over the course 1-2 years.However, the study did not take into account other lifestyle factors like diet so we cannot say exactly what contributed to their unique microbiome profiles.Sato and his colleagues further demonstrated that isoalloLCA could inhibit Clostridium difficile growth in laboratory-cultured Clostridium difficile. This common gut bug causes severe diarrhea and inflammation of the colon.Odoribacteraceae was administered to mice infected by C. difficile. This treatment decreased the amount of C. difficile found in their droppings to below detectable levels. This suggests that it may have helped them fight off the infection.The researchers concluded that isoalloLCA is the most powerful antimicrobial agent selective against gram positive microbes including multidrug resistant pathogens.These lab experiments help to explain how bacterial species found among centenarians may offer some protection from infections via bile acid, but other experts are less confident.Kim Barrett, a research physiologist at UC San Diego who was not part of the study, said that the study is similar to others that try to link specific microbiome signatures to particular conditions in humans.Barrett says that bile acids, on the other hand are emerging as an alternative class of intestinal hormones. They appear to do more than aid fat digestion and absorption.She says, "It is definitely possible that manipulating specific bile acid concentrations, whether they are microbial, or giving them directly to the body, could confer health benefits."Probiotics containing live bacteria that are believed to have health benefits have shown mixed results. Therefore, more research is required before any bacteria-packed pills can be considered long-lasting.There are many other factors that can be done to prolong life, such as staying connected, reducing stress, and eating well.Nature published the research.
