What we know about Gut Health in 2024. The current scientific evidence for gut supplements.

We all know that gut health is important. Over the last decade the amount of research into this topic has increased massively.

Most of the old science of how to promote gut health still holds true. A balanced diet, with a variety of fruits and vegetable to provide the types of dietary fibre we need to support healthy digestion and support our gut microbiota.

Our gut microbiota are literally trillions of bacteria that live in our large intestine (commonly referred to as our gut) and are made up of hundreds of different species all that may have different effects on the body.

Due to the complexity of our gut ecosystem trying to figure out the exact types and amounts of bacteria we need, identify what a healthy gut really looks like and how we can positively impact it and how this effects the body has become a huge challenge for science to understand and as practitioners challenging to know exactly what strategies to apply, to who and when.

There is still to a certain extent an element of educated guesswork on what we do and what expect to see as an outcome.

The purpose of this blog then, is to discuss the current state of play, what evidence exists for nutrition and supplement interventions to improve gut health and when they might be most useful.

Why is Gut Health Important?

Our gut bacteria can influence our metabolism, help protect the lining and maintaining the integrity of our gut, preventing cell death, and priming and supporting the immune system and protecting us against harmful bacteria and may even influence our brain and muscle function. They are also essential to produce vitamins and minerals such as Vitamin K and folate.

What are Probiotics & Prebiotics?

Probiotics: These are described as “live microorganism that when given in appropriate amounts that are beneficial to human health”.

Prebiotics: These are forms of carbohydrates and fibre that our gut bacteria can use as fuel. There are other substances such as certain fatty acids that can also be used in this way, but when most people talk about prebiotics, they are probably talking about compounds that fit under the broad umbrella of types of carbohydrate including dietary fibre.

Synbiotics: These are products that contain both probiotics and prebiotics.

That’s level 1 complete.

Let’s go a little deeper.

Probiotics: There are lots of different bacteria in the gut of which the most commonly used (and assumed to be beneficial) in products are the strains; Bifidobacterium, Lactobacillus, Saccharomyces, Streptococcus, Enterococcus, Escherichia and Bacillus.

Some strains appear to have unique properties in the body (e.g. neurological, immunological or endocrinological effects) that may be linked to their specific clinical benefits with many strains appearing to have multiple benefits.

These benefits are strongly related to the production of Short Chain Fatty Acids (SCFAs), lactate and acetate which can be used as fuel by different cells and systems in the body.

Probiotic products are available mainly in the form of dietary supplements, including tablets, capsules, powders, liquids and other formulations. Probiotics are also added to commercial yogurts and cultured milk drinks (e.g. kefir).

The consumption of traditionally fermented foods and drinks has been associated with health benefits. Fermented dairy products (mainly yogurt) have been associated with reduced risk of several diseases in some studies, however the evidence isn’t entirely clear.  

What benefits do Probiotic Supplements Have?

Despite the ongoing research into probiotics there appears to be a highly individual response to their consumption and the conditions under which they are more or less effective.

A few things we do know is that despite a belief that the human gut profile was fairly fixed after the first few years of life. That changes to diet, under certain medical circumstances and even in the healthy gut of some people that probiotics can cause short term changes to the bacterial profile.

Even when the overall composition of the gut is not significantly changed, there have been reported benefits in terms of production of nutrients, fuel for the gut and reduction of bad bacteria.

Most of the significant benefits however appear to come after illness and/or the use of antibiotics which may also kill our healthy gut bacteria and when the body is under periods of immune system stress like during travel or in the winter months when the ‘usual’ bugs are doing the rounds.

Here are 5 positive takeaways on the potential health benefits of probiotics for healthy adults:

  1. Probiotics may help boost your immune system and protect against common colds.
  2. Probiotics could improve your digestive health by relieving abdominal discomfort and normalizing bowel movements.
  3. Probiotics may support vaginal and post-birth health in women by increasing healthy vaginal bacteria.
  4. Some studies show probiotics can increase levels of beneficial gut bacteria, though the effects may be temporary.
  5. Early research suggests probiotics may benefit mental health by reducing stress, anxiety and depression.


More on Prebiotics.

Our Gut bacteria are influenced by many factors including our age, background and of course our diet. It is the undigested components of food that our gut bacteria feed on.

The effects of different types of diet, fibre, and other ‘food’ for our bacteria we are still trying to figure out. However, the general advice remains the same as it always has... we should consume a diet rich in fruits and vegetables with some cereals and ‘brans’ to provide the right blend of fibre in the diet.

One of the challenges of understanding how to optimise our own gut lies in understanding how we respond to different type of fibre in the diet. For example, too much of one type of fibre (or too much fibre in total) for some people can cause constipation and bloating whereas for other people they may need to increase fibre intake above and beyond recommended amounts to help with gut problems.

Remember that trial and error is still a valid approach to figuring things out. However, for those who suffer with GI issues you must be methodical in your approach to figuring out what helps, what doesn’t and working with different combinations of foods and supplements in order to find your sweet spot.  

About the author:
Dr Paul holds a degree in Sports Science, post-graduate degrees in Sport Rehabilitation & Sport Nutrition and a PhD in Biomechanics.
He is a SENr Nutritionist and works with elite athletes and has written thousands of articles, blogs on all aspects of health and fitness. He is a 'hybrid' athlete, competing in both ultra-endurance events and powerlifting, recently completing a 100km trail ultra-marathon. 
Find him on instagram @theperformancestrategist or on his blog www.hybridathleteblog.co.uk