Everyday habits for a healthier gut: what the evidence supports

There is no single food, drink or tea that keeps the gut healthy on its own. What health services recommend is a set of ordinary habits: regular, unhurried eating, plenty of fibre from different foods, enough fluids, daily movement, enough sleep and ways to manage stress. This guide sets out what the UK's National Health Service (NHS), the World Health Organization (WHO) and the US National Institutes of Health (NIH) say about each, including what is known, and not known, about popular herbal teas.

Regular, unhurried meals

For people with irritable bowel syndrome (IBS), the British Dietetic Association (BDA) advises eating three regular meals a day and trying not to eat late at night. How you eat matters as well as what: the US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) suggests eating more slowly and, when you can, sitting down to eat rather than eating on the run, so you swallow less air.

The NHS adds a few points about what goes on the plate:

• fatty foods, such as chips, burgers and fried foods, are harder to digest and can cause stomach pain and heartburn, so grill rather than fry when you can;
• spicy food does not bother everyone, but if it gives you heartburn, stomach pain or diarrhoea, go easy on it;
• if particular foods seem to cause symptoms, a food diary can help you work out which ones.

Our guides to eating late and gas and bloating go into more detail.

Fibre from a variety of foods

Fibre is the habit with the most support. The NHS recommends 30g a day for adults, and says most adults in the UK eat only about 20g. WHO recommends at least 25g a day of fibre that occurs naturally in food, along with at least 400g of fruit and vegetables a day for everyone over 10.

Variety matters, the NHS says: get fibre from different sources, such as wholemeal bread, brown rice, fruit and vegetables, beans and oats, because relying on one type of food may not give you a balanced diet. If cereals and grains bring on bloating, it suggests getting more of your fibre from fruit and vegetables instead. When you add fibre, do it gradually, the NHS advises, and drink enough with it: fibre absorbs water, and without fluid it cannot do its job.

Your large intestine is also home to bacteria. According to NIDDK, they help break down the remaining nutrients in food and make vitamin K. Our guide to constipation covers fibre in more detail.

Enough fluids

The NHS suggests 6 to 8 cups or glasses of fluid a day as a guide, and more if it is hot, you are active for long periods, or you are unwell. Pale yellow pee is a good sign that you are drinking enough. Water, lower-fat milk and lower-sugar drinks, including tea and coffee, all count. Fruit juice and smoothies are high in sugar, so the NHS suggests no more than one small glass (150ml) a day.

If you are prone to heartburn or bloating, the NHS notes that drinks with caffeine can trigger heartburn in some people, and fizzy drinks tend to bloat the tummy. It suggests drinks that are not fizzy and have no caffeine, such as water, milk and herbal teas, and, if you cannot do without coffee or tea, keeping to 1 or 2 cups a day.

Daily movement

The NHS recommends that adults do at least 150 minutes of moderate activity a week, or 75 minutes of vigorous activity, plus strengthening activities on at least 2 days a week, and that they break up long periods of sitting. For digestion specifically, the NHS says a daily walk or run can help you poo more regularly.

Sleep and stress

On average, adults need 7 to 9 hours of sleep, the NHS says. Its advice for better sleep includes keeping regular sleep times, avoiding tea, coffee and alcohol for at least 6 hours before bed, and not eating a big meal late at night.

Stress can show up in the gut. The NHS lists stomach problems among the physical symptoms of stress, and sleeping or eating too much or too little among the changes in behaviour it can cause. Talking about your feelings, exercise, breathing exercises and planning ahead for stressful days are among the steps it suggests, and it advises seeing a GP if you are struggling to cope.

Where ultra-processed foods fit

Most foods are processed in some way, the NHS points out, and processing is often useful: pasteurising milk makes it safe, and freezing or tinning helps food last. Ultra-processed foods have been through more processing and often contain ingredients you would not use at home, such as preservatives, sweeteners and emulsifiers. Examples include sweetened drinks, crisps, packaged cakes and biscuits, and some ready meals.

Not all of them are unhealthy. The NHS notes that wholemeal sliced bread and baked beans can be part of a healthy diet. But many ultra-processed foods are high in calories, saturated fat, salt or sugar, and diets high in them have been linked to obesity, type 2 diabetes and heart disease; it is not yet known whether the processing itself or the fat, salt and sugar is to blame. Most people would probably benefit from eating fewer of those high in saturated fat, salt or sugar, the NHS says.

WHO's guidance points the same way: base meals on a variety of minimally processed and unprocessed foods, keep free sugars below 10% of daily energy and salt below 5g a day. Food labels help you compare products.

What about herbal teas?

The NHS lists herbal teas, alongside water and milk, as drinks that do not contain caffeine and are not fizzy. Claims that particular teas "fix" digestion are another matter. Here is what the National Center for Complementary and Integrative Health (NCCIH), part of the NIH, says:

• Peppermint. Very little research has been done on peppermint leaf, the part used to make the tea, and there is not enough evidence to say whether it is useful for any health condition. Peppermint tea appears to be safe, although the long-term safety of large amounts is unknown. Most research is on concentrated peppermint oil in capsules, a different product. Note that NIDDK lists mint among the foods commonly linked to acid reflux symptoms.
• Ginger. There have been many studies of ginger, but some have not been of high quality, and most of those on nausea tested dietary supplements rather than foods. Taken by mouth, ginger can cause side effects such as abdominal discomfort, heartburn, diarrhoea, and mouth and throat irritation.
• Fennel. Fennel is not among the herbs in NCCIH's fact sheets, and we found no NHS guidance on fennel tea, so we cannot say whether it does anything for digestion.
• Ayurvedic blends. NCCIH says there is little scientific evidence on the value of Ayurveda for most health issues. It also warns that some Ayurvedic preparations may contain lead, mercury or arsenic in amounts that can be toxic; in a 2015 survey, 40 percent of people using Ayurvedic preparations had raised levels of lead in their blood.

If you take any medicines, are pregnant or breastfeeding, or have a health condition, NCCIH advises talking to your doctor before using herbal products, because some herbs and medicines interact. It also advises against using Ayurvedic products as a reason to put off seeing a doctor.

When to see a doctor

Everyday habits are not a substitute for medical advice when something changes. See a GP if you notice a change in your poo that is not usual for you, such as diarrhoea or constipation, blood in your poo, tummy pain, a lump in your tummy, bloating, or weight loss without trying, the NHS advises.

Get medical advice urgently, the same day, if your poo is black or dark red, or you have bloody diarrhoea.

Call your local emergency number if you are bleeding non-stop from your bottom, or there is a lot of blood or large blood clots when you poo.