Centenarians' secret: A healthy gut boosts longevity

By Alpana Mohta, MD, DNB, FEADV, FIADVL, IFAAD | Fact-checked by Hale Goetz
Published July 4, 2024

Key Takeaways

  • Bacteriophages in the digestive system are viruses that infect beneficial gut bacteria and promote metabolic functions like sulfate reduction and methionine conversion.

  • Recent research has found that centenarians have higher gut virome diversity and abundance, which may protect against aging-related diseases by supporting mucosal integrity and inhibiting the growth of aerobic pathogens.

  • While healthy aging in centenarians is influenced by genetics (by as much as 40%), maintaining healthy diets, physical activity levels, and strong social networks are also significant contributors.

Recent research is showing just how crucial the gut microbiome is for our health. It’s not just about digestion; it impacts our immune system, heart health (gut-heart axis), and even our brain function (gut-brain axis). The gut microbiome also controls hormone levels and the pancreas-liver axis. Any dysregulation within these axes can disrupt the human body's homeostasis. 

Centenarians are noted to be less susceptible to many infectious diseases, chronic inflammation, and age-related illnesses.[] These properties have been attributed in part to their distinct gut microbial structure.

Centenarians’ unique microbiome

While the role of gut bacteria has been extensively studied, the virome, or the viral component of the microbiome, has often been overlooked. And bacteriophages seem to be a big part of the answer. 

  • A Nature report found that centenarians' gut microbiomes produce unique secondary bile acids, like lithocholic and isoallolithocholic acids, which have antimicrobial properties against gram-positive multidrug-resistant pathogens such as Enterococcus faecium and Clostridioides difficile.[]

  • In a report from Frontiers in Cellular and Infectious Microbiology, centenarians with good cognitive function had a higher abundance and diversity of gut microbiome species than younger subjects.[]

Understanding bacteriophages

Bacteriophages are a unique class of viruses that specifically target bacterial cells. They latch onto the bacterial cell membrane and inject their DNA or RNA. This process can change how bacteria behave and influence the whole microbial community in the gut.

A 2022 study showed that bacteriophages can improve memory and cognition in mice.[] Previous research also shows that human newborns and infants have high levels of replicating bacteriophages, but this slows down in adulthood.[]

Figuring out how gut viruses impact aging has been tough, however, because viral genomes are hard to extract from microbiome samples. 

Role of bacteriophage in aging

Researchers publishing in Nature Microbiology compared the gut virome of centenarians from Japan and Sardinia with older subjects aged 60 and above and younger subjects aged 18 and above, using data from previous studies.[] The gut microbiome diversity and abundance—both bacterial and viral—were significantly higher in centenarians compared with the other two groups.

Interestingly, centenarians also had more active viral replication than younger adults. The study used advanced deep-learning techniques to analyze viral data from stool samples—discovering a total of 4,422 viruses, of which 1,746 were novel.

Lead author Joachim Johansen, PhD, from the University of Copenhagen's Novo Nordisk Foundation Center for Protein Research, stated in a press release, “High microbial diversity is usually associated with a healthy gut microbiome.”[]

"We expect people with a healthy gut microbiome to be better protected against aging-related diseases."

Joachim Johansen, PhD, University of Copenhagen press release

Phage-encoded auxiliary functions revealed a higher potential for converting sulfate to sulfide, methionine to homocysteine, and taurine to sulfide, supporting mucosal integrity and resistance against aerobic pathogens. 

Dr. Johansen further said, “We have learned that if a virus pays a bacterium a visit, it may actually strengthen the bacterium. The viruses we found in the healthy Japanese centenarians contained extra genes that could boost the bacteria. We learned that they were able to boost the transformation of specific molecules in the intestines, which might serve to stabilize the intestinal flora and counteract inflammation.” 

Study researchers also noted that while altering human genetics to promote longevity is not feasible, modifying the gut microbiome composition is a viable strategy. 

Are centenarians really designed differently?

A 2023 report in Nutrients noted deaths from infectious diseases have plummeted since the 1900s with medical advances.[] However, as people live longer, the risk of dying from age-related chronic illnesses is on the rise. Centenarians manage to stay healthy despite their age by avoiding these chronic diseases.

Although a person's life expectancy is 20%–40% dependent on their genetic makeup, healthy aging is also influenced by diet and lifestyle. Centenarians are known to share healthy lifestyle traits—good diets, consistent physical activity, strong social networks, and participation in mindfulness activities that help give life purpose. By encouraging these healthy practices with your own patients, we can help them live longer, healthier lives.

What this means for you

Scientists have long investigated phage therapy to destroy pathogens, but now we understand that bacteriophages can also enhance bacterial hosts by providing genes that enable new metabolic abilities, protecting against age-related diseases. While phage therapy for the gut microbiome is still developing, promoting healthy aging through a balanced diet, regular exercise, strong social ties, purposeful activities, and probiotic-rich foods can support a healthy gut microbiome and protect against age-related diseases.

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