Could Antibiotic Use Reduce Protective Effects Of Breastfeeding?

Evidence continues to emerge about the importance of a resilient gut microbiome for our short and long term health.

The gut microbiome refers to the bacterial community in our gut, and a resilient gut microbiome is one that is more diverse and less likely to shift towards unhealthy bacteria.

A loss of gut microbiome resilience has been observed in a number of diseases, including obesity, diabetes, metabolic syndrome, autoimmune diseases and allergy.

In its early stages, the gut microbiome is highly plastic (meaning it can be easily altered) and influenced by the effects of early life events.

As the baby develops, the gut microbiome loses its plasticity and so becomes more resistant to change.  This might ‘lock in’ an ideal or a non-ideal gut microbiome well into adulthood.

It seems that what happens in our early years could have the biggest impact on the development of our gut microbiome. One of the earliest influences is how we are fed as babies.

How Babies Are Fed Influences Their Gut Microbiome

Research has shown that there are significant differences between the bacteria in the guts of breastfed babies and those of formula fed babies.  Breastmilk has the perfect mix of probiotics (bacteria) and prebiotics (food for the bacteria) to help a baby develop a healthy gut microbiome. In fact, oligosaccharides (prebiotics) make up the third most abundant component in breastmilk; it has more than 200 kinds!

Breastfed babies take in bacteria from the mother’s skin and from her milk. These bacteria are the beneficial type which live in the gut and on the skin, helping to keep babies healthy.

Could the use of antibiotics in early life affect how breastfeeding influences the development of the gut microbiome? Recent research suggests it could.

Early Antibiotic Use Could Reduce Some Of Breastfeeding’s Protective Effects

Altered gut bacterial composition in infancy and frequent antibiotic use in early childhood are associated with excessive weight gain in children. Early-life gut bacterial composition also influences development of the immune system. One way breastfeeding can help reduce, or attenuate, infection and the risk of overweight/obesity is through its positive effects on the development of our gut microbiome.

However, a recent study found early-life antibiotic use in children could reduce some of the longer-term effects of breastfeeding on weight development and lifetime antibiotic use, possibly due to antibiotic use altering the gut microbiome.

This study was a retrospective cohort study of 226 Finnish children aged 2-6 years, conducted between June and December last year. The study assessed whether antibiotic use in children, while breastfeeding, influenced the effect of breastfeeding on post-weaning antibiotic use and body mass index (BMI) scores.

Among the 226 children, 113 had no antibiotic use before weaning, and 113 had early-life antibiotic use.

Each Month Of Breastfeeding Reduced The Number Of Post-Weaning Antibiotics

The study found that among the 113 children with no antibiotic use while breastfeeding, each month of breastfeeding reduced the average number of post-weaning antibiotic courses by 5% (meaning a 60% reduction in post-weaning antibiotic use in children breastfed for one year).

Also, each month of breastfeeding was estimated to have a 9% stronger reduction in BMI scores among the children with no antibiotic use while breastfeeding, compared with those who had early-life antibiotic exposure.

Among the 113 early-life antibiotic users, each month of breastfeeding decreased post-weaning antibiotic use by 4%, and the effect of breastfeeding on BMI score disappeared.

The study also found that each month of breastfeeding was associated with a 6% reduction in the number of antibiotic courses throughout the first year, and that babies who were breastfed for one year had a 72% reduction in antibiotic courses, compared with babies who were not breastfed.

Significantly Less Good Bacteria In Faecal Matter

In 42 of the children, faecal matter was also analysed, to assess whether antibiotic use while breastfeeding influenced the bacterial composition of their faeces.

Of these 42 children, the children:

• with short breastfeeding duration (0-6 months) and no early-life antibiotic use, or
• with longer breastfeeding duration (8-16 months) and early-life use of antibiotics (as compared with those with longer duration of breastfeeding and no early-life antibiotics)

…had a 55% lower Bifidobacterium bacteria and 71% lower Akkermansia bacteria, both of which are beneficial in the gut. Lower levels of Bifidobacterium and Akkermansia have been found in overweight/obese children.

It’s important to note that information on the duration of exclusive breastfeeding was not available.

This study concluded that “Antibiotic use in a child during breastfeeding may weaken the beneficial effects of long breastfeeding duration. The results suggest that particularly the long-term metabolic benefits of breastfeeding are conveyed by the intestinal microbiota.”

Limitations Of This Study

It’s important to note that this study did not take into account potentially confounding factors such as birth method (i.e. vaginal or C-section), lifestyle, maternal education, or maternal BMI.

Some aspects of the study also limit the extent to which the results can be generalised, such as:

• the exclusion criteria of the study (e.g. milk allergy, lactose intolerance, congenital heart disease requiring regular medication, malignant diseases)
• exclusion criteria for the children providing the faecal samples (i.e. only those without recent and moderate lifetime use of antibiotics, normal BMI, and no asthma or allergy)
• all children in the study were ethnically highly homogeneous, attended day care, and lived in the same Finnish region, and were therefore exposed to a shared environment and diet.

The results of this study provide some useful insights into the possible negative effects of early antibiotic use and the importance of breastfeeding in the development of our gut microbiome. It must be noted, however, that when antibiotics are required to treat a bacterial infection, they can be lifesaving. This is not to say that they are required for every fever or infection.

Recommended Reading: What Is The Best Way To Treat A Fever?