The gut microbiome and the host usually live together in a commensal manner.  However, gut bacteria can potentially be harmful if the ecosystem undergoes abnormal changes with an associated shift in gut microbial composition. This can be caused by a number of external factors, resulting in a dramatic alteration of the symbiotic relationship between the gut bacteria and the host.

The imbalance between the beneficial and pathogenic bacteria in the gut is often referred to as dysbiosis and may cause several diseases.¹

What causes the imbalance in the gut microbiome?

Specific factors such as diet, the use of medicinal products including antibiotics can produce a significant impact on the gut microbiome.

Are children more affected than adults?

The effect of these factors is more relevant early in life, when the gut microbiome has not yet fully established². A child aged 3-24 months may be given 1 course of antibiotics per year, therefore potential changes to the gut microbiome could happen at an early age.

Do all antibiotics affect the gut microbiome the same way?

The extent to which the gut microbiome changes after antibiotics depends on the chemical nature of the antibiotic or combination of antibiotics and also the type of administration, duration and dose as well as the level of resistance that the gut microbiome develops. Not all bacteria in the gut microbiome are impacted to the same degree by the currently available antibiotic interventions.³

One study showed that the gut microbiome of subjects recovered to near-baseline composition within 1.5 months, after completing a course of antibiotic therapy, although 9 common species, which were present in all subjects before the treatment, remained below the level of detection in most of the subjects after 180 days⁴. Importantly one of the species that didn’t recover was bifidobacteria.   

Bifidobacteria is an important species as studies have shown it be important for gut health and it also produces metabolites such as butyrate which is particularly important for colon health.

The gut microbiome can confer protection against pathogens, a phenomenon referred to as colonisation resistance which is when good bacteria effectively crowd out the pathogenic bacteria. This positive effect can be severely impaired by antibiotic treatment.⁵

How to help mitigate the effects of antibiotics on gut health?

• Promote a diet high in fermentable (prebiotic) fibre. A diet high in whole, plant-based, gut-healthy fruits and vegetables will contain non-digestible prebiotic fibre that will help to feed the beneficial bacteria in the gut. Antibiotic-resistant genes are lower in those individuals with diets based on fermented foods and low antibiotic consumption.⁶
• Take supplements to improve gut health. Probiotics and prebiotics may help to reduce the negative effects of the antibiotics on the gut microbiome. Boost your intake of natural dietary prebiotics with prebiotic supplements, which help the good bacteria in the gut to thrive, correcting any imbalance that may potentially occur. They act as a fertilizer, feeding the good gut bacteria, stimulating their growth and helping them thrive so they can support gut health and improve overall wellbeing. Probiotics, on the other hand, may seed the gut with beneficial bacteria to keep things in balance.

In summary, the use of antibiotics can negatively impact the balance of beneficial bacteria in the gut, which can lead to both acute and chronic conditions. Maintaining good gut health before, during and after taking antibiotics, may help to restore the gut microbiome to healthy levels, thereby maintaining or improving gut health and general wellbeing.