The intestines in old age

The aging gut – how the microbiome changes in old age and what role Bacillus subtilis plays in research 

Category: Health & Prevention
Microbiome, gut, aging processes, Bacillus subtilis, scientific classification

Introduction – Why the gut is re-evaluated in old age

The human body undergoes profound changes with age. These changes affect not only muscles, bones, and metabolism, but also, and especially, the gut. Only in the last two decades has the age-related transformation of the gut microbiome become a focus of research.

Today the following applies:
The aging process in humans is closely linked to changes in the intestinal flora.

This realization has fundamentally changed the view of the "senior gut" – from a purely passive digestive system to a central regulatory space of the aging organism .

What actually changes in the gut with age

Numerous observational studies show that the microbiome differs systematically in several aspects in old age:

• Microbial diversity decreases
• The individual stability of the microbiome decreases.
• The ratio of certain microbial groups is shifting
• Metabolic profiles of gut bacteria change

These changes occur gradually over many years. They are influenced by:

• changed eating habits
• lower food diversity
• reduced physical activity
• Medication intake
• age-related changes in the intestinal mucosa

The intestines of older people are therefore biologically different from those of younger people – even if this is often not immediately noticeable externally.

Age, intestinal barrier and microbial regulation

One particularly intensively researched topic is the so-called intestinal barrier . It separates the internal body cavity from the microbially colonized intestinal lining. With increasing age, the following often become apparent:

• structural changes in the mucous membrane
• altered mucus layer thickness
• modified immune cell distribution

These factors can alter the interaction between the microbiome and the immune system . The gut thus remains a central site of biological control processes even in old age – albeit under altered conditions.

Why spore-forming bacteria are being studied particularly in old age

Against this background, some research focuses specifically on microorganisms that possess particular ecological properties under altered intestinal conditions. These include spore-forming bacteria , such as Bacillus subtilis .

Spore-forming bacteria differ from classic intestinal bacteria in the following ways:

• exceptional environmental and acid resistance
• high stability against external influences
• specific ecological adaptation mechanisms

From a microbiological point of view, they are not considered classic permanent inhabitants of the intestine, but rather transient microorganisms that can temporarily pass through the digestive tract and interact with the existing microbial ecosystem there.

It is precisely these properties that make them particularly interesting for research in the context of age-related changes in the intestinal environment .

Bacillus subtilis in the context of the aging microbiome

Bacillus subtilis is an intensively researched spore-forming microorganism that has been studied for decades in both environmental microbiology and food and microbiome research.

In connection with the aging gut, scientists are particularly interested in:

• its high survival rate in the digestive tract
• its interaction with existing microbial communities
• its metabolic activities in the intestinal environment
• its strain-specific characteristics

The following is important:
A functional evaluation is always strain-specific and context-dependent.
General statements about "Bacillus subtilis" without a clear strain definition are not permissible from a scientific point of view.

Why the elderly gut is not a "deficient gut"

An important shift in perspective in modern gerontology is:
The intestines of older people are not simply "weakened", but are biologically regulated differently .

Age-related changes are not a flaw in the system, but rather part of a long-term adaptation process . Therefore, what is crucial is not a return to a "youthful state," but an understanding of these age-related physiological characteristics .

This is also where modern microbiome research comes in:
The focus is not on correcting individual values, but on stabilizing complex microbial equilibria in old age.

Current state of research

Research into the interplay of age, gut microbiota, and spore-forming bacteria is rapidly evolving. Many questions are currently being addressed in:

• Observational studies
• microbiological model experiments
• metabolomic analyses

investigated. Long-term clinical evaluations are still underway for numerous aspects.

However, there is agreement that:

• The microbiome develops its own independent biological profile with age.
• Stable microbial systems play a central role in physiological regulatory processes.
• Spore-forming microorganisms possess special ecological properties that will be further investigated in this context.

The real aha moment

Perhaps the most important change in perspective is:

The intestine of the elderly person is not a passive factor in aging – it is an active participant in the aging process.

And:

It is not only the decline of certain bacteria that is relevant, but also the long-term dynamics of microbial ecosystems.

This shifts the focus of systemic aging biology from a purely functional perspective to the aging gut.

Factual summary

• The gut microbiome undergoes structural changes in old age.
• Microbial diversity often decreases.
• The intestinal barrier shows age-related adaptations.
• Spore-forming microorganisms such as Bacillus subtilis possess special ecological properties.
• Current research views the elderly gut as an active regulatory system.

Legal notice

This article is for informational purposes only. It does not constitute medical advice, a treatment recommendation, or a health claim as defined by the EU Health Claims Regulation (Regulation (EC) No. 1924/2006) .

Author Andreas Kraus
Owner and Managing Director Professional Lead

Editorial and Research Selina Kraus
Journalist BA Master studies in management and leadership of online marketing