Infant Health and Live Bacteria / Probiotics

Infant Health and Live Bacteria / Probiotics

The first 1000 days are the most significant in a child’s development (physical, cognitive, social and emotional) and ongoing health through life, this encompasses pregnancy, infancy and toddlerhood. As with all parts of health, the first 1000 days are also key to the development of a child’s microbiome, which in turn will influence physical and mental health as they age. An estimated 70-80% of immune function stems from the gut, showing that a healthy gut is also key for a well-functioning immune system.

How is the microbiome created at birth?

The infant microbiome is primarily developed at birth, with a range of factors influencing the colonisation of the gut, this ranges from delivery method to birthing environment. The gut bacteria adjusts regularly as a child is introduced to solid foods and different environments, this typically matures to a stable composition over the first 2-3 years of life.


How a baby is delivered can alter the initial colonisation of the gut. In a natural birth, as the baby travels through the birth canal they are exposed to a huge variety of bacteria in the maternal vaginal tract. The quantity and quality of friendly bacteria in the vaginal tract varies depending on maternal health and their microbiome. The predominant genus of bacteria in the vaginal tract is Lactobacillus, providing an environment where pathogenic bacteria cannot survive.

Cesarean section is becoming a much more popular option for births, whether this is personal preference or due to medical reasons. However, with this method of delivery, the initial bacteria that a baby is exposed to is that existing in the hospital and on the doctors and nurses performing the C-section. A result of C-section over natural birth is significantly lower friendly bacteria, eg bifidobacterium, and higher presence of possible pathogenic bacteria in the infant. C-section infants are found to have more occurrences of allergies, asthma, IBD, obesity and diabetes at a later stage in life. However, the research in this area is still ongoing and there are other factors that can influence the development of these conditions, it does not rely solely on one aspect.

Maternal Influence

The maternal influence on an infant’s gut microbiome encompasses many factors including obesity, smoking, maternal diet, maternal lifestyle and antibiotic use during pregnancy.


An intake of antibiotics at any stage in life may cause imbalances in the gut microbiome, as they do not discriminate between friendly and pathogenic bacteria. Studies show that use of prenatal antibiotics, antibiotics in the first 6 months and antacid medication in the first six months is associated with an increased risk of allergy development than those who were not exposed to any medication at this early stage. Antacid medication works by reducing the acidity of the stomach acid, which would usually kill off unwanted bacteria to prevent it making its way down to the intestine. This does not mean these medications should be avoided completely as antibiotics can be life-saving for mothers or babies with bacterial infections. However it does indicate that these infants may require additional support for their gut microbiome development.


As with adults, the infant microbiome is heavily influenced by their food, however in the early period this will have less variety, either breastmilk or formula milk. There are a number of reasons why an infant may be fed with formula milk rather than breastmilk, and this is a perfectly healthy option if it is more suitable for mother and baby.

Breastmilk contains live bacteria, immunoglobulins (antibodies), protein, enzymes, complex sugars/prebiotics, and more to protect the infant against infection, inflammation, aid immune development, organ development and form a healthy and diverse microbiome. The high content of complex sugars known as oligosaccharides in breastmilk is the main influence on the gut microbiome, as this aids growth of healthy bacteria.

Formula milks have been developed to act in the same way as breastmilk, through addition of prebiotics, however studies have shown that babies who are exclusively breastfed have a higher population of friendly bacteria (e.g. Bifidobacterium and Bacteriodes) and lower presence of potentially pathogenic bacteria(Streptococcus and Enterococcus) than exclusively formula-fed infants.

Mid to long-term feeding with breastmilk appears to have the longest lasting effect on gut health, superior tomedication and delivery method. Weaning from an earlier age appears to influence the microbiome by maturing it faster, while infants still breastfeeding alongside consuming solid foods in late infancy have a more varied microbiome.

Health concerns involving the microbiome

Digestive upset (colic/constipation/bloating/gas)

Infantile colic is also known as excessive crying syndrome, and while the cause of this syndrome is unknown, it has increasingly been associated with the gut microbiome. In particular, this association is shown with infants who appear to have a decreased abundance of the Lactobacillus genus of bacteria.

Skin concerns

The inflammatory skin condition, eczema, is present in one in five children worldwide with the development of this frequently beginning in infancy. There are many factors that influence eczema, including genetic predisposition, the skin barrier, environment, nutrition and the microbiome and immunologic development associated with this. The use of probiotics for prevention is researched increasingly and in particular strains from the Bifidobacterium genus andLactobacillus genus are associated with supporting the gut microbiome in infants.


Asthma is a concern for many young children and the current statistics show 1 in 11 children are diagnosed with asthma in the UK. Research suggests that the main influences on risk of developing asthma are geneticpredisposition, environment and the gut microbiome. Risk is further increased in cases where there is antibiotic use in infancy, an indication of how important the gut flora is in immunology.

Immune system

The gut contains around 70-80% of immune cells, therefore gut health is vital for a good immune system.

Mood, brain and behaviour

Studies have repeatedly shown the link between the gut bacteria and the brain, as this bacteria can secrete mood-regulating neurotransmitters, including serotonin, the stabilising hormone, and dopamine, the happy hormone. An imbalance in the gut microbiome has been associated with mood disorders and hyperactivity in children showing that the gut may influence a child’s psychological development as well as physical development.

When to consider probiotics / live bacteria supplements?

So, with all of this in mind, when should you consider a probiotic supplement for your child? Birth through a cesarean section and prenatal or early exposure to antibiotics may lead to a need for additional support of beneficial bacteria. Some signs which may be associated with the gut microbiome are lactose intolerance to breastmilk and formula, baby thrush, colic or reflux, recurrent infections and allergies or skin conditions. When looking for a supplement suitable for infants it’s vital to ensure they are formulated specifically for that age and contain the appropriate strains. A probiotic formulated for adults or even older children, may work differently in thebody of an infant as their microbiome is in the developmental stage and will have different strains of bacteria present. If you have any concerns about a supplement for your child, always check with your healthcare practitioner.

Ongoing support

Probiotics can add the beneficial bacteria into the gut, and some may also contain prebiotics which enable thisbacteria to thrive, however it is also important to provide ongoing support for the microbiome. Two key areas to focus on are hydration and fibre intake. Hydration is key for gut health, as the digestive tract is coated in a mucosal liningthat requires water to function.

Prior to weaning, an infant achieves the hydration they need through milk, however when being introduced to solids it is important to ensure this is accompanied by water. High fibre foods support the healthy bacteria by acting as a food source to encourage their survival and colonisation.

Related Products

Infant & Baby Drops

Sources & Further Reading

Association Between Use of Acid-Suppressive Medications and Antibiotics During Infancy and Allergic Diseases inEarly Childhood

Asthma facts and statistics

Breastfeeding: a key modulator of gut microbiota characteristics in late infancy Development of the GutMicrobiome in Children, and Lifetime Implications for Obesity and Cardiometabolic Disease

Comparison of gut microbiota in exclusively breast-fed and formula-fed babies

Effects of gut microbiome and environment on the development of eczema in Chinese infants.

Factors affecting early-life intestinal microbiota development.

Gut Microbiota Dysbiosis and Role of Probiotics in Infant Colic

Human milk composition:Nutrients and bioactive factors

Infant diet and maternal gestational weight gain predict early metabolic maturation of gut microbiomes

Probiotics and infantile atopic eczema

Shaping the gut microbiota by breastfeeding

Stunted microbiota and opportunistic pathogen colonisation in caesarean section birth Temporal development ofthe infant gut microbiome

The Human Microbiome and Child Growth – First 1000 Days and Beyond

The infant microbiomedevelopment: mom matters

The Infant Microbiome: Implications for Infant Health and Neurocognitive Development

Three distinct stages ininfant microbiome development identified

Share This