- Fibre and a wide variety of plant foods are the best supported ways to support your gut.
- Fermented foods such as yoghurt and kefir may help, though the evidence is still developing.
- Probiotics help in specific situations, not as a general health boost.
- Stomach trouble during training is common and usually fixable with timing and food choices.
- Persistent changes in bowel habit, blood in your poo or weight loss need a GP visit.
What gut health actually means
Your gut, particularly the large intestine, is home to trillions of bacteria and other microbes, known as the gut microbiome. They help break down fibre, produce useful compounds and interact with your immune system. Research in this area has grown enormously, and it is clear the microbiome matters for health.
What is much less clear is how to 'optimise' it. The science is young, and much of it comes from animal studies or observational research. That has not stopped a flood of products claiming to fix your gut. A useful rule: if it sounds too good to be true, or comes with an expensive subscription, be sceptical.
In everyday terms, gut health for most people means comfortable digestion, regular bowel movements, and no ongoing pain, bloating or urgency. That is a sensible goal to focus on.
What the evidence supports
- Fibre: aim for 30 g a day, as UK guidance recommends. Gut bacteria ferment fibre and produce compounds that support the gut lining. Our guide to fibre shows how to reach it.
- Plant variety: eating a wide range of vegetables, fruit, wholegrains, beans, nuts, seeds, herbs and spices is linked with a more diverse microbiome. Variety across the week matters more than any one superfood.
- Less ultra-processed food: diets high in ultra-processed food tend to be low in fibre and plant variety.
- Regular exercise: people who are regularly active tend to have more diverse gut bacteria, and movement helps keep bowels regular.
- Sleep and stress: the gut and brain are closely linked. Poor sleep and chronic stress often show up as gut symptoms.
None of this needs special products. Porridge with fruit and seeds, a bean chilli with vegetables, a stir fry with several different vegetables and a pot of live yoghurt already tick most of these boxes.
Fermented foods and probiotics
Fermented foods such as live yoghurt, kefir, sauerkraut, kimchi and miso contain live bacteria and other compounds produced during fermentation. Some research suggests regularly eating them may increase microbiome diversity, but the evidence is still developing. If you enjoy them, they are a good addition. If you do not, there is no need to force them.
Probiotic supplements are more complicated. Different strains do different things, and benefits found for one strain do not apply to others. There is reasonable evidence for some probiotics in specific situations, such as reducing diarrhoea linked to antibiotics, but not for general use in healthy people. If you want to try one for a specific problem, ask a pharmacist or GP which, if any, might help.
Prebiotics are types of fibre that feed gut bacteria. They are found naturally in foods such as onions, garlic, leeks, asparagus, bananas, oats and beans, so a varied diet provides them without supplements.
Stomach trouble during training
Gut problems during exercise are very common, especially with running, jumping and high-intensity work. During hard exercise, blood flow is diverted away from the gut to working muscles, and the jostling of running adds to the problem. Symptoms include stitches, cramping, nausea, reflux and urgent trips to the toilet.
Most cases improve with a few changes:
- Leave two to three hours after a full meal before hard training, or keep the pre-training snack small and simple.
- Avoid high-fibre, high-fat and very spicy food in the few hours before sessions.
- Sip fluids rather than downing large amounts just before or during training.
- Practise fuelling during long sessions. The gut adapts with training.
- Be cautious with anti-inflammatory painkillers such as ibuprofen before hard exercise, as they can irritate the gut. Check with a pharmacist if you use them regularly.
Our guide on what to eat before a workout has timing and food ideas that suit sensitive stomachs.
Bloating, IBS and food intolerances
Occasional bloating is normal, especially after large meals or when you increase fibre quickly. Ongoing bloating, pain and changes in bowel habit may be irritable bowel syndrome, which is common. IBS is diagnosed by a GP, often after ruling out other conditions.
If you suspect gluten is a problem, do not cut it out before seeing your GP. Coeliac disease is diagnosed with a blood test that only works if you are still eating gluten. Cutting it out first can lead to a false negative result.
Restrictive diets, such as the low FODMAP diet used for IBS, can be very effective but are complicated and not meant to be followed long term. They are best done with support from a registered dietitian, who can help you reintroduce foods and avoid unnecessary restriction. Your GP can refer you.
When to see a GP
Most gut symptoms are not serious, but some need checking. See your GP if you have:
- A change in your usual bowel habit, such as looser poo or constipation, lasting three weeks or more
- Blood in your poo or bleeding from your bottom
- Losing weight without trying
- Ongoing tummy pain, a lump in your tummy or bloating that does not go away
- Extreme tiredness for no obvious reason
- Difficulty swallowing or persistent heartburn
Go to A&E or call 999 for severe tummy pain that comes on suddenly, vomiting blood, or black, tarry poo, which can be signs of bleeding. Stress and poor recovery affect the gut too, which our guide to stress and recovery explores. If you want to build training and eating habits that support your gut and energy, you can try Lycan Strength with the 7-day free trial.
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Questions
How can I improve my gut health naturally?
Eat 30 g of fibre a day from a wide variety of plant foods, drink enough fluid, stay active, sleep well and manage stress. These habits have far better evidence than most supplements.
Do I need to take probiotics?
Most healthy people do not. Specific probiotics can help in certain situations, such as after antibiotics, so ask a pharmacist or GP if you have a particular problem.
Why do I need the toilet when I run?
Running jostles the gut and diverts blood flow away from it. Eating less fibre and fat before runs, timing meals earlier and practising fuelling usually helps.
General guidance for healthy adults. If you have a medical condition, injury or are pregnant, check with a health professional before changing your training or diet.
