As You Age, Your ‘Microbiome’ Changes

WEDNESDAY, Oct. 6, 2021 (HealthDay News) -- The key to eternal youth may lie in our guts.

Advancing age seems to change the makeup of the microbiome in the small intestine, and in the future, it may be possible to tweak this bacterial milieu and boost longevity, new research suggests.

The gut microbiome is made up of trillions of microorganisms and their genetic material. The diversity of these organisms is believed to play a role in promoting health and well-being.

With normal aging, the bacteria in the small intestine shift from microbes that prefer oxygen (aerobic bacteria) to those that can survive with less oxygen (anaerobic bacteria). There is also an increase in coliform bacteria in relation to other organisms with advancing age, the study showed.

The new study is observational and not designed to say how, or even if, these changes affect aging. "We don't have correlations here in terms of cause and effect," said study co-author Dr. Ruchi Mathur. She is an endocrinologist and director of the Cedars-Sinai Diabetes Outpatient Treatment & Education Center in Los Angeles.

For this study, the researchers looked at microbial changes that occur in the small intestine with chronological age, medication use, and diseases in people aged 18 to 80.

The small intestine is located further up the digestive tract and is about 20 feet long. "It is where really cool stuff happens. It's more metabolically active and may play a greater role in human health and diseases than the large bowel," Mathur said.

Previously, the same team mapped the microbiome of the entire gastrointestinal system and noted pronounced differences along the digestive tract.

When researchers compared bacterial populations in the small intestines based on age alone, the oldest individuals in the study had a more significant shift from aerobic to anaerobic bacteria and a greater proportion of coliform bacteria compared with their younger counterparts.

Coliforms can become too abundant in the small bowel with age and exert a negative influence on the rest of the microbial population. "They are like weeds in a garden," Mathur said.

The number of medications a person took and the number of diseases they had were associated with other changes in bacterial diversity in the small intestine. "Certain microbial populations are influenced more by medications, while others are more affected by certain diseases," she said. "We have identified specific microbes that appear to be only influenced by the chronological age of the person."

If future studies validate these findings, treatments targeting the bacterial changes linked to aging alone may help prolong life. "If we can tease out the organisms that increase with chronological age, we can develop specific targets to manipulate them and see if we can make changes in longevity," Mathur said.

The next step is to see if the findings hold in people aged 80 to 100, she said.

Many people take probiotic supplements to help reset the balance between good and bad bacteria in their gut to improve their health. But "it's way too early to consider taking probiotics to manipulate the bacteria in the small intestine," Mathur said.

The findings were published in the Sept. 28 issue of Cell Reports.

"This study helps further our understanding of the gut microbiome and what happens to it during the aging process," said Dr. Elena Ivanina, director of neurogastroenterology and motility at Lenox Hill Hospital in New York City.

More research is needed before drawing any conclusions about how the gut microbiome affects longevity. The study results start a conversation that someday may lead to anti-aging and metabolic therapy through microbiome modulation, said Ivanina, who has no ties to the new research.

More information

Learn more about the gut microbiome and how it influences health at the Harvard T.H. Chan School of Public Health.

SOURCES: Ruchi Mathur, MD, endocrinologist, director, Diabetes Outpatient Treatment & Education Center, Cedars-Sinai, Los Angeles; Elena Ivanina, DO, director, neurogastroenterology and motility, Lenox Hill Hospital, New York City; Cell Reports, Sept. 28, 2021