The gut microbiome is not something we are born with fully formed. Instead, it develops gradually throughout life as microbes begin to colonise the body from the moment of birth.

During infancy, childhood and adulthood, the microbiome evolves into a complex ecosystem containing trillions of microorganisms. These microbes interact with the digestive system, immune cells and metabolic pathways throughout the body.

Researchers now recognise that early microbial exposure plays an important role in shaping the microbiome. Understanding how the microbiome develops helps explain why diet, environment and lifestyle can influence gut health throughout life.

Founder Insight

Hanna Sillitoe first became interested in the role of the gut microbiome while naturally treating her psoriasis. During this time she began exploring research into how gut bacteria influence inflammation, digestion and immune responses.

This experience sparked a long-standing interest in how the microbiome develops and how supporting microbial balance may influence health and wellbeing.

The Microbiome at Birth

For many years scientists believed the womb was a completely sterile environment. Today, most researchers agree that the majority of microbial colonisation begins during and immediately after birth.

During vaginal birth, newborns are exposed to microbes from the mother's birth canal and surrounding environment. These early microbes begin to populate the infant’s digestive system.

These initial microbial communities play an important role in the early development of the gut ecosystem.

The Infant Microbiome

In the first months of life, the microbiome changes rapidly as infants are exposed to microbes through feeding, contact with caregivers and their environment.

Breast milk contains compounds known as human milk oligosaccharides, which act as food for certain beneficial bacteria in the infant gut.

During infancy, microbes begin to establish themselves within the digestive system, gradually building a more complex microbial ecosystem.

The Childhood Microbiome

As children grow and begin eating a wider variety of foods, the microbiome becomes more diverse.

Diet plays an important role in shaping microbial communities during this stage. Fibre-rich foods, fruits and vegetables provide nutrients that feed different microbial species.

Environmental exposure also influences the microbiome during childhood, including contact with natural environments, animals and other people.

By around three years of age, many aspects of the microbiome begin to resemble the microbial patterns seen in adults.

The Adult Microbiome

In adulthood, the microbiome typically becomes relatively stable, although it can still change in response to factors such as:

• diet
• lifestyle habits
• stress
• illness
• medications such as antibiotics

A healthy adult microbiome usually contains hundreds of different microbial species living together in balance within the digestive system.

Researchers continue to study how microbial diversity and balance influence digestive health and overall wellbeing throughout adulthood.

What Research Shows

Scientific research has revealed that the microbiome develops through a complex interaction between genetics, environment and lifestyle.

Research findings include:

• Microbial colonisation begins at birth – Early exposure to microbes helps establish the initial microbiome in infants.

• Breast milk supports beneficial microbes – Human milk oligosaccharides help nourish specific bacteria within the infant gut.

• Diet influences microbiome diversity – As children begin eating solid foods, diet plays an important role in shaping microbial composition.

• The microbiome stabilises in early childhood – By around three years of age, many aspects of the microbiome begin to resemble adult patterns.

These discoveries highlight how the microbiome evolves throughout life and responds to environmental and dietary influences.

Sources

Dominguez-Bello MG et al. Delivery mode shapes the acquisition and structure of the initial microbiota. PNAS, 2010.

Yatsunenko T et al. Human gut microbiome viewed across age and geography. Nature, 2012.

Bäckhed F et al. Dynamics and stabilization of the human gut microbiome during the first year of life. Cell Host & Microbe, 2015.

Sender R et al. Revised estimates for the number of human and bacterial cells in the body. PNAS, 2016.

Supporting the Microbiome Throughout Life

Although the microbiome develops early in life, everyday habits can continue to influence microbial balance throughout adulthood.

Eat a diverse range of plant foods

A variety of plant foods provides different types of fibre that nourish a wide range of microbes.

Increase fibre intake

Fibre acts as a primary fuel source for many beneficial bacteria.

Include fermented foods

Fermented foods such as kimchi, sauerkraut and kefir contain naturally occurring microorganisms that may help support microbiome diversity.

Maintain healthy lifestyle habits

Sleep, stress management and physical activity can influence microbiome balance.

Consider probiotic support

Some people choose to support their microbiome with probiotics — live microorganisms designed to help maintain microbial balance within the digestive system.

Common Questions About Microbiome Development

When does the microbiome develop?

Microbial colonisation begins around the time of birth and continues to evolve throughout infancy and childhood.

When does the microbiome become stable?

Many aspects of the microbiome begin to resemble adult patterns by around three years of age, although the microbiome can continue to change throughout life.

Can lifestyle influence the microbiome in adulthood?

Yes. Diet, stress, sleep and environmental exposures can all influence the composition of the microbiome.

Conclusion

The gut microbiome develops gradually from birth through childhood and into adulthood. During this time, microbes colonise the digestive system and form a complex ecosystem that interacts with many systems in the body.

Although early life plays an important role in shaping the microbiome, research shows that diet, lifestyle habits and environmental exposures can continue to influence microbial balance throughout life.

Supporting the microbiome through diverse plant foods, fibre and healthy lifestyle habits may help maintain balance within this complex ecosystem.

Some people choose to support their microbiome with probiotics — live cultures designed to help maintain a healthy balance of gut bacteria. Learn more about our Multi-Strain Biotic and how it supports gut health.