Fibre has had something of an image change. Once mostly associated with bran cereal and bowel regularity, it is now at the centre of fibremaxxing: the push to eat more fibre for better gut health.

In the UK, adults are advised to eat around 30g of fibre a day. Most of us eat considerably less. But reaching 30g, or going beyond it, isn't the whole story.

Different fibres behave differently in the gut. The food they come in matters too, as does the community of microbes already living there.

Is fibremaxxing actually good for you?

For most people who aren't eating enough fibre, increasing it is a good place to start. The UK recommendation is around 30g a day, ideally from a mix of wholegrains, beans and pulses, vegetables, fruit, nuts and seeds. If your intake is currently low, build it up gradually. A sudden increase can cause bloating, wind and discomfort.

Fibremaxxing becomes less helpful when the aim shifts from eating enough fibre to simply eating as much as possible. Two meals can contain the same number of fibre grams without providing the same types of fibre or behaving in the same way in the gut.

Beyond the fibre count

• Why fibre isn't one nutrient
• Do you really need 30 plants a week?
• Why food structure matters
• Does a healthier gut always mean more microbial diversity?
• Where do immunity, skin and hormones fit?
• Which foods give you different types of fibre?
• How should you increase fibre?
• Fibre and probiotics aren't interchangeable

Fibre isn't one nutrient

We talk about fibre as though it is one thing, but it actually comes in many forms.

Some fibres hold water or form gels. Some add bulk to stools. Others are fermented by the microbes living in our gut. Resistant starch passes through the small intestine without being fully digested and reaches the large intestine.

What happens there depends partly on the fibre itself and partly on the microbes already living in your gut. This is one reason the same foods can affect people differently.

Do you really need 30 plants a week?

You've probably heard the advice to eat 30 different plants a week for your gut. It's a useful reminder to eat widely, but it isn't an official UK recommendation.

Our UK guidance is much simpler: adults should aim for around 30g of fibre a day.

There is good reason to keep variety in mind. Different plants bring different fibres and plant compounds to the diet, and a 2026 UK trial found that a blend of more than 30 plant ingredients changed the composition of the gut microbiome over 6 weeks. The study didn't establish 30 as a magic number.

Think variety rather than a weekly score: wholegrains, beans and lentils, vegetables, fruit, nuts and seeds all count.

Why food structure matters

The form our food comes in can change how we digest it. Take a chickpea and chickpea flour. They're the same food, but grinding breaks down some of the chickpea's structure, making what's inside easier for our digestive enzymes to reach.

Cooking and cooling can make a difference too. When foods such as potatoes or rice are cooked and then cooled, some of their starch can become resistant starch, which reaches the large intestine where gut microbes can ferment it.

The amount varies depending on the food and how it's prepared, so there's no need to start eating all your potatoes cold. It's simply another example of why the fibre number on a label doesn't tell us everything.

Does a healthier gut always mean more microbial diversity?

Not necessarily. Healthy people can have very different communities of gut microbes, and there isn't currently one microbiome score that can tell you whether your gut is healthy.

This is important when microbiome tests, foods or supplements suggest that increasing microbial diversity should always be the goal. Diversity is useful to researchers, but more diverse and healthier don't mean exactly the same thing.

Where do immunity, skin and hormones fit?

This is where fibre becomes more interesting than digestion alone. When gut microbes ferment certain fibres, they produce compounds called short-chain fatty acids, which interact with the gut lining and are involved in immune and metabolic processes.

The gut and skin communicate through immune, microbial and metabolic pathways too, what you may know as the gut–skin axis. Research in this area is growing, although we can't say that eating more fibre will clear acne, eczema or rosacea.

There is a hormone connection as well. Compounds produced in the gut can influence hormones such as GLP-1 and PYY, which help regulate appetite and metabolism.

These connections are part of why a varied, fibre-rich diet matters beyond simply keeping us regular. They also remind us that immune, skin and hormonal health are complex, and no single food or nutrient works in isolation.

Which foods give you different types of fibre?

There isn't one “best” source of fibre, which is why variety is useful.

Oats and barley contain beta-glucans, a type of soluble fibre. Beans, chickpeas and lentils provide several types of fibre as well as resistant starch. Fruit and vegetables contribute different fibres, including pectins, alongside vitamins, minerals and plant compounds. Wholegrains, nuts and seeds add still more variety.

You don't need all of them at every meal. Eating across these foods during the week is a simple way to bring different fibres into your diet without turning it into another thing to count.

How should you increase fibre?

Start with what you already eat. Choose wholegrain bread more often, add beans or lentils to a familiar soup or stew, keep the skin on potatoes where appropriate, or add another vegetable to dinner.

If your current fibre intake is low, increase it gradually and drink enough fluid alongside it. A sudden increase can cause bloating, wind and discomfort.

Pay attention to how you feel too. A food can be nutritious without being comfortable for you in every quantity.

Fibre and probiotics aren't interchangeable

Fibre and probiotics are often talked about together, but they do different jobs.

Some fibres provide food for microbes already living in the gut. Probiotics introduce specific live microorganisms, so one isn't a replacement for the other.

It's also why we developed Flora Daily Biotic with both gut and skin health in mind. Each delayed-release capsule contains 20 billion live cultures from 9 probiotic strains, alongside 10mg of zinc, which contributes to the maintenance of normal skin and normal immune function.

For us, it sits alongside a varied, fibre-rich diet rather than replacing one.

A more useful way to think about fibre

If there's one thing we'd take from fibremaxxing, it's the reminder to look beyond the usual few plant foods we eat each week.

Try a different grain. Add lentils or beans to something you already make. Pick up a fruit or vegetable you haven't bought for a while. Small changes are often much easier to keep than chasing a perfect daily number.

A few common fibre questions

Can you eat too much fibre?

Increasing fibre very quickly can cause bloating, wind and digestive discomfort, particularly if your usual intake is low. In the UK, adults are advised to aim for around 30g a day, building up gradually rather than treating it as a number to exceed.

Do fibre supplements work as well as fibre from food?

Fibre supplements can provide particular types of fibre, but they aren't the same as eating a varied diet. Whole plant foods bring different fibres alongside vitamins, minerals and other plant compounds.

Is fibre always good for your gut?

Fibre is an important part of a healthy diet, but that doesn't mean every type or amount will feel right for everyone. If increasing your fibre repeatedly causes pain or persistent digestive symptoms, speak to an appropriately qualified healthcare professional.

Continue exploring

• What Is the Gut–Skin Axis and How Does It Affect Skin Health?
• How does the gut support hormonal balance and mental wellbeing?
• How to support oestrogen levels and female health with probiotics

For more from By Sarah, follow @bysarahlondon, where we share more on skin, wellbeing and life behind the brand, alongside nutrition and gut-health insights from our Co-founder and Registered Nutritionist, Sarah.

And if you have a question of your own, we're always happy to help. Email us at care@bysarahlondon.com and we'll come back to you personally.

This Journal article is for general information and isn't intended to diagnose or treat a health condition. If you have persistent or unexplained digestive symptoms, seek personalised advice from an appropriately qualified healthcare professional.

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