The importance of a balanced gut microbiome

From the inside of our gut to the surface of our skin, our bodies are host to thriving communities of microbial life, including bacteria, viruses, archaea and fungi. The most diverse and abundant community of microorganisms lives inside the gut and is known as the gut microbiome. These living microorganisms perform a variety of important functions within the gut and can influence many different aspects of our health with both local and far reaching effects. Just as Hippocrates proclaimed over 2000 years ago that all disease begins in the gut, it is now widely accepted by modern science that the influence of the gut microbiome extends far beyond our digestive tract with effects on our immune system, skin health, bone health and more (2).

When the different types of microorganisms that make up the gut microbiome are well-balanced, the gut microbiome has beneficial effects on our health. With a healthy diet and lifestyle, the different types of microbes that live in the gut and their abundance generally remain stable over time. However, external influences such as a low fibre diet and antibiotic administration can disrupt its composition and create an environment that allows unfavourable microorganisms to overgrow. When these microorganisms become too dominant, the gut microbiome has the potential to negatively impact our health. It’s therefore essential for our health to support a gut microbiome that houses many beneficial microorganisms and to restore balance when it becomes disrupted.

Antibiotics do save lives

Antibiotics are important for fighting off bacterial infections and have helped to save countless lives since their discovery in the 1940s. While preserving a diverse and abundant gut microbiome is important for our health, antibiotics cannot be avoided during an active infection and their benefits far outweigh the risks. Therefore, many people are interested in using probiotics alongside a course of prescribed antibiotics in order to support their gut microbiome and reduce the risk of side effects.

However, many commonly prescribed antibiotics are broad spectrum which means they act against a wide range of bacteria - including beneficial bacteria that are part of the gut microbiome (3). Their effects against beneficial bacteria are the main reason why some people experience antibiotic side effects.

What are common side effects of antibiotics?

One of the most immediately felt consequences of antibiotics, and one that people are keen to avoid, is antibiotic-associated diarrhoea (AAD). This highlights the incredibly important role that beneficial gut bacteria play in regulating our digestion. AAD is a sign that these beneficial bacteria have been diminished, and non-beneficial bacteria have been able to overgrow, causing inflammation in the gut and creating diarrhoea (4). Recent research has correlated the use of antibiotics with an increased risk of long-term adverse health outcomes, such as an increased risk of asthma, depression and anxiety, and their effects on the gut microbiome have been speculated as the potential cause of this (5).

Can probiotics help with side effects of antibiotics?

Yes, certain strains of probiotics such as Lactobacillus rhamnosus GG have been shown to significantly reduce the risk of antibiotic-associated diarrhoea and help to support the balance of beneficial bacteria (6). In the gut, Lactobacillus rhamnosus GG helps to prevent the overgrowth of non-beneficial bacteria by taking up space on the gut lining and competing for nutrients (7). It is thought that as antibiotics reduce the population of beneficial bacteria in the gut, regularly supplementing beneficial probiotic bacteria can help to fill the gaps that they leave and ensure the gut microbiome doesn’t become dominated by non-beneficial microorganisms.

Should you take a probiotic before, during or after a course of antibiotics?

Many people delay starting a probiotic until after they have finished their course of antibiotics. This is because it’s often thought that probiotic bacteria taken alongside antibiotics will be ‘killed off’ and won’t be able to exert their beneficial effects. However, research shows that this is not the case. As described above, specific probiotic strains such as Lactobacillus rhamnosus GG have protective effects against antibiotic side effects when taken at the same time and are not wasted when taken alongside an antibiotic.

The research (8,9), tells us that this strain of probiotic is:
1. Effective when taken alongside a course of antibiotics
2. Most useful for preventing antibiotic-associated diarrhoea, and
3. Less effective when started after antibiotic-associated diarrhoea has already begun.

This evidence supports the use of this specific probiotic strain from the day you begin your course of antibiotics.

Do probiotics and antibiotics need to be separated by two hours?

For those who are using probiotics alongside antibiotics, they are often advised to take them two hours apart. It has now been established that specific probiotics are clearly beneficial even in the presence of antibiotics. However, it is hypothesised that this two hour window may help to preserve the activity of probiotic bacteria for greater effects. Unfortunately, the research doesn’t yet specify whether probiotics should be taken at the exact same time as the antibiotic or two hours away from them. Due to how the body digests, absorbs and distributes antibiotics around the body, it is unlikely that separating the doses would make much of a difference. When in doubt, it is best to follow the advice of your healthcare professional.

Should you keep taking probiotics after your course of antibiotics?

As well as preventing antibiotic-associated diarrhoea, probiotic supplements can provide a number of additional benefits following antibiotics such as helping to repair the gut and promote gut health, support the restoration of beneficial gut bacteria, and enhance the immune system

Probiotics can help to reduce inflammation in the gut caused by the reduction of beneficial bacteria by antibiotics, and help to repair damage to intestinal cells that may have been caused by this increased inflammation. Specific probiotic strains, such as Lactobacillus rhamnosus GG and Lactobacillus plantarum 6595, have been shown to improve the health of epithelial cells and promote healing by reducing inflammation,. By improving the health of the cells that line the gut, probiotic bacteria can help to create an environment that supports the growth of beneficial microorganisms and restore balance to the gut microbiome.

Boosting the immune system with probiotics

As well as preventing antibiotic-associated diarrhoea, probiotic supplements can provide a number of additional benefits following antibiotics such as helping to repair the gut and promote gut health, support the restoration of beneficial gut bacteria, and enhance the immune system

Probiotics can help to reduce inflammation in the gut caused by the reduction of beneficial bacteria by antibiotics, and help to repair damage to intestinal cells that may have been caused by this increased inflammation. Specific probiotic strains, such as Lactobacillus rhamnosus GG and Lactobacillus plantarum 6595, have been shown to improve the health of epithelial cells and promote healing by reducing inflammation (10,11). By improving the health of the cells that line the gut, probiotic bacteria can help to create an environment that supports the growth of beneficial microorganisms and restore balance to the gut microbiome.

Avoid unnecessary antibiotic prescriptions with immune-boosting probiotic strains

Enhancing immune system function is also an important aspect of antibiotic recovery and can help us to maintain health in the long term. Antibiotics are ineffective against viral illnesses such as the common cold and flu; yet, many patients are inappropriately prescribed antibiotics for these common respiratory infections. By taking care of our immune system and working to reduce the occurrence of these viral infections, we may also help to avoid unnecessary antibiotics. Two specific probiotic strains, Lactobacillus paracasei 8700:2 and Lactobacillus plantarum HEAL9, have been shown to help enhance immune system function and reduce the number, duration and severity of common colds compared to placebo (12,13). Supplementing with targeted probiotic strains such as these may help to keep you well and avoid unnecessary antibiotic prescriptions in the long-term.