Gut health is a subject that has been gaining prominence over recent years.

Nutritionists, dietitians and doctors are becoming more interested in how the balance of gut flora can impact general health. Google trends tells us that searches around gut health have been increasing over the past five years and this looks set to continue.

In order to find out more about gut bacteria and how it can affect health, we spoke to Dr Anton Emmanuel, Medical Trustee for Guts UK, a UK-based gut health charity.

What do we mean by ‘the gut’?

The gut is also known as the gastrointestinal tract. It starts at the mouth and runs through the body and ends at the anus. The gut involves several organs all essential to the digestion process, including:

  • the oesophagus
  • the stomach
  • the small intestine
  • the large intestine
  • the colon
  • and the rectum.

Muscle contractions and enzymes are also crucial to the digestion process. Most beneficial nutrients are absorbed by the small intestine. Any food that cannot be digested or is classed as a waste substance is expelled from the body in faeces. This includes potentially damaging germs or bacteria.

But, besides digesting the food we consume, what else does the gut do?

Dr Emmanuel explains: ‘To the best of our knowledge the main function is that it works alongside the body’s immune system to help deal with stuff that comes into the gut. For example: things that you accidentally consume. Therefore, its primary function is digestive, but it also helps your body to know what it is dealing with in terms of being able to manage content that comes into your intestine.’

‘It does that by helping immune function as well as working in tandem with your gut’s immune system to create this ‘gut barrier’, which allows selected things to come through the barrier (such as nutrients) and filters out certain things to be disposed of, like toxins or bacteria, that could cause harm.’

Good bacteria and bad bacteria

A basic understanding of the bacteria in the gut may be that some of the bacteria is classified as ‘good’ and some of it as ‘bad’.

But just what do we mean by ‘good’ bacteria and what does it actually do?

As Dr Emmanuel explains: ‘At the moment most people think along the lines of good bacteria and bad bacteria, but it’s much more subtle than that. The key is to think of it as a balance of bacteria rather than particularly good ones or bad ones. Certain patterns of bacteria or fermentation can result in bad things happening.’

There are numerous factors that have the potential to influence the bacteria in the gut. Our diet, use of antibiotics, environment, general health and genetics all play a part in our gut microbiome (this term refers to the microorganisms found in a particular environment).

‘Bacteria produce other general immune compounds that have an affect on your immune system throughout your body, so we know that altering gut bacteria can improve things like arthritis and skin diseases which are driven by the immune system. They have more general immune activation properties.’ Dr Emmanuel tells us.

‘Finally, bacteria also probably has a role in deciding how much we eat and what we eat. It has a function in how it controls your appetite.’

Testing the gut microbiome

So, is it possible to find out if we are harbouring the right balance of bacteria in the gut?

Unfortunately not.

At the moment we don’t have good enough tests to tell us.’ Dr Emmanuel explains.

‘We are not able to do a test, either from stools or a biopsy of the bowel, to say “you have too much of x and not enough of y”. This sort of test doesn’t currently exist but it is hopefully on the horizon. What we do have is essentially bacteria which we know are potentially helpful; and so we can say these can make a difference. But the chances of us having an investigation to examine stools to say “you have too much of x or y” isn’t there right now. However, it is something that is currently being pursued and forms part of the research agenda in the area of gut health.’

There has been increasing interest in gut microbiome testing, but in its current stage, it is unlikely to provide any significant data that will have a direct impact on your gut health. Due to the individual nature of the gut, it is better to think of the gut microbiome as a spectrum. Therefore there should be no one size fits all approach.

Prebiotics and probiotics

Those looking to improve their gut health may have heard of prebiotics and probiotics. Various food brands have picked up on these scientific terms and now include them when referring to their food products.

But what do these terms mean?

Dr Emmanuel explains:

  • Prebiotics are the food stuffs that allow certain bacteria to grow in the gut.
  • Probiotics are actual bacteria itself and it is certainly true that you can have beneficial bacteria.’

He goes on to say that it is possible to enhance your diet by making sure you are eating pre- and pro-biotics as, ‘fermented food and fibrous roughage can encourage gut bacteria.’

However, the complex nature of each individual gut microbiome makes it difficult to pinpoint the exact bacteria one person might be lacking, or have in abundance, when compared to another person.

Dr Emmanuel reminds us that: ‘Your gut bacteria is as unique as your fingerprint. The technology to be able to say you need more of x and less of y is not there at the moment. We do not have that degree of understanding yet.’

That being said, it is still a good idea to keep your gut in mind when thinking about your diet.

Dr Emmanuel tells us that it is: ‘unquestionably true that there is a chance to enhance health by adjusting gut bacteria. However, the science isn’t as neatly defined as that at the moment. It’s tantalising because we know a bit, but not quite enough to be entirely useful.’

Is there a specific diet that can benefit gut health?

Some gut disorders may be treated with diet and lifestyle changes. However, not everyone needs to make dramatic changes to notice slight improvements in their gut health.

Below are some examples of foods or diets that have been linked with better gut health, but as Dr Emmanuel illustrates, it isn’t a case of following any one diet in particular.  

  • Low fodmap

‘At the moment there is a very trendy diet called the low fodmap diet which is used in relation to IBS and can be seen to have benefits for some IBS patients.’

The diet involves limiting carbohydrates for a set period of time.

Fodmap is an acronym which stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. Foods that are categorised as high in fodmaps include garlic, onions, mushrooms, beans, lentils and wheat. Dietitians may propose this type of diet to IBS patients, however, people who have not been diagnosed with IBS symptoms may want to exercise caution before considering this type of diet.

As Dr Emmanuel goes on to say: ‘We know that people who are overly observant of the low fodmap diet, or stick to it too closely or for too long, can experience problems due to a less diverse bacterial family. Therefore we don’t want people to overdo low fodmaps for too long.’

The implementation of a low fodmap diet should be under the supervision of a specially trained dietitian.

  • Fermented foods

There are certain foods that we can introduce to our diet to help encourage the bacteria in our gut and fermented food, as a natural probiotic, is probably top of the list.

Dr Emmanuel says: ‘It is clear that fermented foods can help encourage gut bacteria to proliferate. Therefore things like:

  • kimchi
  • kefir
  • miso
  • pickle
  • and sauerkraut

are all food stuffs where the bacteria, or their chemical composition, encourages the gut to produce more bacteria.’

The above listed food stuffs are classed as probiotics but it also important to make sure that your diet contains prebiotics too.

Fermented food and fibrous roughage can encourage gut bacteria. The most naturally occurring prebiotics include fibre and roughage and consuming them can help benefit gut health; however, consuming too much of them can result in excess gas.’ Dr Emmanuel explains.

There is no clear data on how frequently you might have to consume these types of food to notice an improvement in gut health.

How can gut health impact our mood?

This particular biological interaction is something many may have experience of. It may have become apparent when you have followed your gut instinct when making an important decision, or you may have had an upset stomach when going through a particularly stressful period of time.

Dr Emmanuel likes to think of the link between the gut and mood as a ‘two way street.’

When we are nervous we may experience a butterflies-in-the-tummy feeling or need to visit the bathroom a couple of extra times. This is one example of how emotions can affect the gut. We also know that the gut can affect emotional state. Within patients that have IBS and other gut disorders, this can affect the brain in its own right.’

Patients with IBS or other gut conditions are more likely to be diagnosed with anxiety or other mental health disorders.

So in theory, the notion of our stomach being our second brain is perhaps not too far from the truth. ‘We talk of the ‘big brain’ in your head and your ‘little brain’ in your tummy having a daily and constant conversation.’ Dr Emmanuel explains. ‘This means that there is potential for emotional things to affect your bowel and this can happen all the time.’

‘The brain and gut are interconnected and that’s why we have this notion of comfort foods; we like eating certain foods because we essentially metabolise them better.’

The gut and exercise

Most of us will know that regular exercise has many proven health benefits including reducing the risk of developing some chronic illnesses, and boosting mood. But the link between exercise and the gut is not conclusive.

There is no evidence that exercise or water drinking has an effect on gut bacteria.’ Dr Emmanuel says. ‘If you are mildly constipated you can use these two things jointly to improve bowel output. But there is no other proven improvements for gut bacteria from these lifestyle choices unfortunately.’

The science behind gut health is ever expanding and there is potential for new findings to have a profound impact on the lives of those struggling with gut disorders.

If you have any concerns or questions about your own gut health then you should contact your GP. For more information on the gut and gut disorders, head over to the Guts UK website.