"There have been a lot of genetics studies that have tried to understand what in genetics makes people live longer and healthier," says Jiangchao Zhao of the Department of Animal Science at the University of Arkansas, "but not much progress has been made in that field."

However, the recent surge of interest in the human gut microbiome in the scientific community has opened some historically locked doors. The idea that the human gut microbiome is linked to healthy mental and physical health is relatively new and unexplored, but recent studies have shown that a healthy gut might be more important than we think. A new study published by Fanli Kong and Jiangchao Zhao of the University of Arkansas Department of Animal Science in Current Biology explores a new link between the gut microbiome and healthy, happy aging.

"People in society are living longer, but not necessarily healthier," says Zhao. "There are a lot of problems. People live longer but suffer from a lot of chronic diseases, so healthy aging is very important. You want to live longer and healthier. You cannot find a good model for healthy aging because when people get older there are almost always some problems."

So, Zhao and collaborators in China went searching and found a special group of people in China in the Sichuan Province. The community is notoriously long-living, spry, and happy, and a high percent of its elders live to be 90 years old, or older. "They are very healthy," said Zhao, "So we thought this would be a perfect model to study healthy aging and the gut microbiome. We asked this question: How does their gut microbiome differ from others? We saw a paper published by an Italian group. They categorized the gut microbiomes of young people and also centenarians. We thought: How do these two populations differ, then?"

The team collected feces from a group of healthy Sichuan elders and a group of randomly selected Sichuan youth, and sequenced their gut microbiomes by using the next-generation Illumina MiSeq platform. The researchers analyzed the gut microbiome data by using the mothur software installed at the Arkansas High Performance Computing Center. Zhao's group used a machine learning technique called "Random Forest" to mine the microbiota data, including overall microbial community diversity and hundreds of different bacterial taxa.

"We identified a lot of different things," said Zhao. "The first thing that we found interesting is the community diversity. The conventional wisdom is that when people get older, their gut microbiota diversity decreases and bad bacteria increases. They [bad bacteria] cause problems, they cause inflammation and chronic disease. What we found is really different. In this special cohort of long-living people, their gut microbiome diversity didn't decrease — they're even higher than the younger group. That's a great indicator of [a] healthy gut. Healthy bacteria were enriched. There might be something in there to make them live happily and healthily. We validated this study with that independent Italian group's data set. We also found a higher community diversity in the older group and those same good bacteria [in the Italian population]. This is an exciting discovery since you don't expect to these many shared features in the two populations given the remarkable differences in their gut microbiotas."

"We don't know if this is a cause or effect," said Zhao. If Zhao and his team are able to find a way to isolate those two factors — an exceptionally diverse and healthy gut microbiome — there just might be a way to make people live longer and healthier. To further validate the study, the team is using fruit flies as models. They plan to inoculate the feces of the healthy populations to fruit flies to see if they live longer and healthier. Assuming that the fruit fly study exhibits positive results, the team also aspires to culture the healthy bacteria found in the feces to make probiotics, which they eventually plan to commercialize and sell. They plan to use animal models, such as pigs, as well, to test this theory.

This is an international collaboration between Jiangchao Zhao and Ying Li's labs at Sichuan Agricultural University in China.