That Gut Feeling

You train hard, (mostly) eat well, and get enough recovery, but could you be missing a key piece of the puzzle? Gut health is a hot topic right now, and it is (quite rightly) really having its moment in the spotlight. But, not all claims are evidence-based, and there’s still a lot we don’t know. Here is what you really need to know about your gut, supplements, and how it may link to performance and health. 

What is Gut Health and Why Does it Matter?

The human gut microbiota refers to all the microorganisms living in your digestive tract (and the microbiome refers to their collective genes... if we’re getting technical). It weighs around 1–2 kg and accounts for about 90% of the total cells in your body; meaning, technically, you’re mostly made up of bacteria!

These bacteria help break down components of food that we can’t digest ourselves, such as fibre and complex carbohydrates, producing a range of by-products. Some of these, like short-chain fatty acids (SCFAs), are highly beneficial, supporting gut lining integrity, reducing inflammation, and providing energy for intestinal cells. But others can be harmful if produced in excess. The balance between these “good” and “bad” microbial activities is what we often mean by 'gut health'. When that balance is disrupted and tipped in the favour of our 'bad' bacteria, it’s known as gut dysbiosis and there are many factors that can cause this.

Mounting evidence links gut dysbiosis to a wide range of health issues: from anxiety and depression, inflammatory bowel disease (IBD) and rheumatoid arthritis, to obesity and type 2 diabetes. It may also play a role in fatigue, poor recovery, and low mood. Meanwhile, a thriving, diverse microbiota has been associated with better energy levels, improved sleep, and overall wellbeing. But, the field is still young and rapidly evolving. As OneTrack Club's Dietician and leading Sports Nutritionist, Renee McGregor, notes:

“no two microbiomes are the same, so it’s hard to determine what is ‘microbially correct'."

This makes research complex, but exciting. To top it all off, relationships with the gut are bi-directional. For example, the gut can affect hormones, but also hormones can affect the gut, so it is extremely difficult to untangle the evidence.

Ultimately, the gut does far more than digest food — it’s a key player in many surprising aspects of health. Through the gut–brain axis, microbes communicate with the brain via nerves, hormones, and immune signals, influencing mood, stress resilience, and even motivation to exercise. A healthy gut also supports immunity, reduces inflammation, and aids nutrient absorption. That said, there’s still so much we don’t know — and that’s what makes this area of research one of the most fascinating frontiers in health science.

What About Exercise and Gut Health?

When it comes to exercise, a recent study by Zhang and colleagues in 2024 concluded:

"Moderate exercise can promote the production of SCFAs and increase the abundance of beneficial bacteria, while excessive exercise can cause gastrointestinal discomfort, increase intestinal permeability, and provoke inflammatory responses."

So basically, some exercise can be good for our gut, but too much exercise can cause issues. The classic bell shaped curve when looking at how something can benefit our health. Too little of something is damaging, but too much of something can also be damaging- so its about finding that right balance.

They go on to say:

"The gut microbiota can improve exercise performance by improving nutrient absorption, regulating energy metabolism, relieving fatigue, boosting skeletal muscle function, reducing oxidative stress, and regulating the neuroendocrine system.

Sounds pretty good, right? But how do we actually improve our gut health to then improve performance?

Improving your gut health

Starting with the diet,OneTrack Club's Dietician Renee, suggested:

"The general advice I give is to eat a varied diet of wholegrains, legumes, fruits, vegetables and fermented food and this will then provide you with the best opportunity to support your gut health."

In addition to eating a varied diet it's important we also look at other aspects of our life within our control as, our gut health is influenced by far more than just what we eat. The brain and digestive system are closely connected through the enteric nervous system (a complex network of neurons within the walls of the digestive tract) AKA the “second brain.” This means stress can directly affect gut function, changing how food moves through the digestive tract and even altering the balance of gut bacteria. Managing stress through techniques like deep breathing, mindfulness, or simply taking time to unwind can therefore make a real difference to digestive comfort and overall gut health.

Other lifestyle factors such as sleep and exercise also play a key role. Poor sleep has been shown to reduce microbial diversity, while regular physical activity can promote a more balanced, resilient microbiome (as long as you're not doing too much!). So, supporting your gut health isn’t just about fibre and fermented foods — it’s about looking after your whole lifestyle.

Do You Need a Supplement?

With gut health supplements filling the shelves, it’s easy to assume we need probiotics or prebiotics to maintain a healthy gut — but that’s not always the case. For most people, a diverse, fibre-rich diet will naturally support a healthy microbiome without the need for pills or powders. Foods such as yoghurt, kefir, kimchi, sauerkraut, and whole grains provide both probiotics (live beneficial bacteria) and prebiotics (the fibres that feed them), creating the ideal environment for your gut microbes to thrive.

That said, there are times when a supplement can be useful. Evidence suggests that certain probiotic strains may help restore balance after antibiotic use, support gut comfort during travel, or ease symptoms in conditions like irritable bowel syndrome (IBS). In athletes, emerging research has found probiotics might reduce gut discomfort during endurance training and even support immune function - though results are mixed.

If you do choose to supplement, it’s worth remembering that not all probiotics are created equal. The effects are strain-specific, so look for products that list the bacterial strain in full and have research behind them. If in doubt, speak to a Dietician or Registered Nutritionist.

Overall, think of supplements as a potential top-up, not a replacement for a balanced diet and healthy lifestyle. A colourful, plant-rich plate, consistent exercise, good sleep, and reducing stress will do far more for your gut health than any single capsule.

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References

• DOI=10.3389/fnut.2023.1207543

• PMID 38890909

• DOI= 10.1146/annurev-food-072023-034458

• DOI= 10.1186/1550-2783-9-45

• DOI= 10.3390/foods12091787

Written by Phoebe Redding (BSc, MSc, ANutr, Dip) a Registered Associate Nutritionist and OneTrack Club Coach.