Eat these two foods weekly to improve gut health and reduce tummy troubles, nutrition expert says

Independent

16-07-2025

In recent decades, the term ' diet ' has become synonymous with weight loss. However, an ever-expanding bank of research tells us that what we eat has impacts extending far beyond the number on our bathroom scales.
The food we consume can affect our mood, energy levels and immune system, among other things; its impact on our gut is central to many of these processes. For this reason, gut health has become a topic of increasing interest for many. 'Our research found that over 40 per cent of adults experience tummy troubles,' explains Holland and Barrett's Emily Foster, a certified nutritionist with a masters degree in applied sport and exercise nutrition. 'This indicates there's a need, now more than ever, to understand how to support gut health. Gut health isn't just about the gut either. It's linked to many more elements of health and it can influence other aspects of the body.'
The path to a healthier gut, Foster says, is a high fibre diet containing 30 or more plant-based foods per week, with prebiotic and probiotic foods providing extra plus-points. But some are better than others. Here, Foster shares the foods she recommends eating weekly to allow your gut microbiome to thrive, and explains the many benefits each one can deliver.
10-second takeaways
Everyone's gut is different, and people are likely to have individual experiences and triggers with their diet. But research supports the idea that a diverse gut microbiome leads to improved gut health and the many benefits that come with it. You can use the advice below to achieve improved gut microbiome diversity and health:
Eat 30-plus different high fibre plant foods per week.
Prioritise prebiotic fruits and vegetables such as asparagus, onions, garlic, leeks, Jerusalem artichokes, apples, berries and bananas. These feed and fuel the beneficial bacteria within the gut.
Aim to consume fermented probiotic fibres such as kimchi, kombucha, kefir, tempeh, miso and sauerkraut at least two or three times per week, varying the ones you eat.
If you are new to fermented foods, introduce them into your diet slowly to minimise any possible digestive discomfort – 'your gut microbiome isn't used to such a rapid influx of these new microbes... it's a sign of the beneficial bacteria getting to work'.
Swap refined grains in your diet like white flour and white rice for whole grains.
Read on for a more detailed list of the ingredients you should be adding to your weekly shopping basket, and why they are worthy of your time.
What is a healthy gut?
A healthy gut is one with a balanced and diverse microbiome, Foster tells me.
'Within our gut microbiome, we have trillions of different microorganisms – you can think of them like a bustling, microscopic city,' she says. 'There are beneficial bacteria, but also some viruses and fungi in there as well. The aim is to keep that balance in the bacteria, and also diversity within the types of bacteria that we have in our gut.
'There was a really interesting study called the American Gut Project [later renamed the Microsetta Initiative] which highlighted that a more diverse diet can lead to a more diverse gut microbiome, and this is linked to a healthier gut microbiome.
'[To achieve this] we want to be consuming plenty of plant fibres to support our gut health. We also want to be consuming lots of different types [of plant fibres] throughout the week as well.'
The foods Foster recommends for improving gut health can be split into two camps: foods rich in dietary fibre, particularly prebiotic fibres, and fermented foods with live cultures – many items in this latter camp fall under the probiotic banner.
Group one: Foods rich in dietary fibre, particularly prebiotic fibres
Fruits (especially those with prebiotic fibres, such as apples, berries, and bananas – bonus points if they are slightly green)
Vegetables (particularly those with prebiotic fibres like Jerusalem artichokes, asparagus, leeks, onions and garlic)
Legumes
Whole grains
Nuts and seeds
The American Gut Health (or Microsetta Initiative) study mentioned above showed that consuming 30 or more different plant foods per week can increase gut microbiome diversity, and thus gut health.
'These are foods like fruits and vegetables, whole grains, beans and lentils, and nuts and seeds – even things like herbs and spices count towards it as well,' says Foster. However, gorging on your favourite fruit will soon see you hit a point of diminishing returns – diversity in your diet should be prioritised.
'If you were to eat a banana today, then you had a banana tomorrow, you wouldn't then be able to count that as a second plant food,' Foster continues. 'You need to consume different types of plant foods to reach that recommended 30 different plant foods per week.'
For this reason, she says look out for 'plant points' on food packaging, so you know how much closer a food is taking you to that elusive weekly target. Of the plant-based foods listed above, Foster gives special mention to prebiotic fibres. These fibres feed and fuel the beneficial bacteria within our gut, promoting a diverse and balanced gut microbiome.
'Some of the big prebiotic fibres I always encourage people to eat are things like asparagus, onions, garlic, leeks and Jerusalem artichokes – these are all prebiotic vegetables,' Foster says. 'Berries and apples contain pectin, which is a type of prebiotic fibre. And bananas, especially slightly green ones, have resistant starch in them, which is again a prebiotic fibre to help feed that beneficial bacteria.
'Things like legumes, lentils, chickpeas and beans also have soluble fibre as well as resistant starch, feeding that good bacteria.'
Another of Foster's recommendations is to swap refined grains in your diet, like white flour and white rice, for whole grains.
'Go for oats, barley, quinoa, brown rice, buckwheat and spelt,' she advises. 'Unlike refined grains, they retain their germ, their endosperm and their bran [the nutrient-rich embryo of the grain, the nutritious tissue that surrounds it, and the hard outer layer of the grain, respectively].
'This makes whole grains rich in various types of fibres that are fermentable by the gut bacteria, again feeding that good bacteria within the gut.
'All fruit, vegetables and fibrous foods are great, but while all prebiotics are types of fibre, not all dietary fibre is prebiotic. Those prebiotic ones I've mentioned are especially beneficial for supporting the gut microbiome.'
Group two: Fermented foods with live cultures
Kimchi
Kefir
Kombucha
Sauerkraut
Tempeh
Miso
Live yoghurt
If you've ever found yourself involved in a discussion about gut health, then someone has probably prescribed you a diet containing kimchi, kefir and kombucha. These are examples of probiotic fermented foods, and they can play a role to play in keeping your midsection content.
'Fermented foods, especially those that contain live cultures, are particularly good for the gut microbiome because they contain the beneficial bacteria strains within them,' says Foster. 'Instead of just feeding what you've already got within the gut, you're actually putting new strains in there as well, which is going to help to support diversity within the gut microbiome.
'Most, not all, fermented foods are probiotics, because not all of them actually contain live cultures. So things like beer, for example, are technically a fermented food, but it's not one we would encourage people to consume more of.'
But, Foster adds, there are 'no official guidelines on how many types of fermented foods we should eat per week'.
'I always recommend aiming to eat them two to three times per week to start off with,' she continues. 'More is even better, and ideally, you are consuming different types of fermented foods on those two to three days, because the different fermented foods will contain different strains of beneficial bacteria.
'One important thing to note is that, if we do incorporate fermented foods into our diet, incorporating them slowly is better because it's quite common to experience a little bit of digestive discomfort when introducing fermented foods for the first time.
'This is because our gut microbiome isn't used to such a rapid influx of these new microbes. And it's a sign of the beneficial bacteria getting to work. It can be beneficial to start small and then gradually increase [the amount of fermented foods you eat] to allow time for your microbiome to adapt.'
Below, you can find Foster's top recommendations for fermented foods to include in your weekly plans.
Kimchi
'Kimchi is a traditional Korean side dish made from fermented cabbage,' Foster says. 'There are usually other vegetables in there, and things like chilli, garlic and ginger as well.
'It contains beneficial strains of bacteria to increase diversity and balance out the gut microbiome, improving overall digestion and potentially enhancing immunity. It's also rich in things like vitamin K and C for general health, and antioxidants from the vegetables that are in it.'
Kefir
'Kefir is a fermented milk drink with a texture similar to a thin yoghurt. It's made with kefir grains, but these aren't actual grains – they're what's called a symbiotic culture of bacteria and yeast, which is known as a SCOBY in a lot of scientific research.
'Again, they offer beneficial bacteria and yeast to support gut microbiome diversity. They have calcium in there as well to support bone health, and protein to support muscle maintenance.'
Foster recommends using kefir in smoothies, overnight oats or even drinking a shot glass of the stuff in the morning. However, she advises being wary of flavoured kefir drinks as these can often contain added sugar.
Kombucha
'Kombucha is a great one because it can be a good alternative to having a fizzy drink in the afternoon or having an alcoholic beverage when you're out,' Foster says.
'It has that beneficial bacteria, but it also has quite a nice flavour to it, so it still tastes like a bit of a treat.'
Tempeh and miso
'Tempeh and miso are both fermented soy,' Foster explains. 'Tempeh comes in blocks, and a lot of vegan recipes use it as a bacon alternative because, if you fry it up or pop it in an air fryer, it has quite a nice taste to it.
'Then miso comes in a little pot, and it's generally an easy one to incorporate within meals – it's really nice to use in Asian dressings.'
The benefits of including high-fibre foods in your diet
'Fibremaxxing' is currently trending on TikTok, and with good reason – there are plenty of benefits to upping your intake. The government guidelines recommend 30g of dietary fibre per day for adults, but many people are currently falling short of this standard, with most managing less than 20g.
'If we fall short of that fibre intake, we're potentially limiting the diversity within our gut microbiome, which is going to have an effect on digestive health and may impact things like nutrient absorption,' Foster explains.
'If we don't have a healthy gut microbiome, it could link to poor immunity, as well as issues with mood or stress through the gut-brain axis link. A low fibre diet also has the potential to be linked to quite a few gut conditions as well.'
But for those able to hit their fibre goals with consistency, many potential benefits await.
A large-scale 2019 review of data from existing studies, published in The Lancet, found that people who met the recommended daily fibre intake had significantly lower risks of dying from, or developing, several major health conditions (coronary heart disease, strokes, type 2 diabetes, colorectal cancer and cancer-related mortality) compared to those with lower fibre intakes, Foster explains.
'Other positive impacts are going to include regular bowel movements and generally improved gut health,' she continues. 'You're feeding that gut microbiome, which has loads of other impacts on a variety of health areas.
'A high fibre diet is linked to better weight management as well, because fibre is quite satiating and helps you feel full – the types of food that are high in fibre tend to be quite low in calories. It is beneficial for things like cholesterol levels and heart health, too.'
Foster adds that everybody's gut is different as a result of their diet, environment and many other contributing factors. This is partly why Holland and Barrett's latest campaign has made gut health one of its key pillars.
'It's about empowering people to take control of their own gut health and educating people that the importance of gut health goes beyond just products and supplements,' says Foster. 'Yes, supplements can be beneficial, but it's also about creating an environment that helps those beneficial bacteria thrive through things like food and lifestyle.
'People go through different experiences [with their gut health] and have different triggers, so it can be really beneficial to get personalised, unique and tailored advice.'
The Independent spoke to Dr Johnny Drain, the scientist-turned-chef who many of the world's top restaurants turn to for all their fermentation needs.