Many of us associate eating enough fibre with a healthy digestive system – but have you ever stopped to think it might also benefit your brain, heart, immunity and even your gums?
Fibre not only helps to keep our digestive system running smoothly but also nourishes the vital community of trillions of microorganisms – known as the microbiome – that supports other health systems, too.
Yet thanks to modern diets high in convenience foods, ready meals, snacks and junk food, a shocking 96 per cent of British adults don’t eat the recommended 30g of fibre a day.
The effects of this deficiency can stretch all around the body – something I see all the time in my work as a nutritionist who specialises in gut and immune health.
The good news is your microbiome is continually shaped by your lifestyle choices, which means it’s never too late to make a difference.
Fibre is the number-one fuel for the beneficial bacteria in your gut, encouraging them to grow and crowd out pro-inflammatory harmful bacteria.
When ‘good’ bacteria feed on fibre they also produce helpful postbiotic compounds, such as short-chain fatty acids, which help reduce the chronic low-grade inflammation that nudges the whole body towards disease over time.
As fibre is found in all plant foods, there are so many delicious yet practical ways you can boost your intake, as I explain in my new book, The Everyday High-Fibre Plan, shared exclusively here with Daily Mail readers in the final part of this special series.
My approach is not to create a strict regimen that is hard to live by but is rather a series of practical suggestions for weaving extra fibre into your normal life.
Read on for tips to avoid bloating and an at-a-glance chart, on the back page of this pullout, showing how much fibre everyday staples contain which you can take with you on your next food shopping trip.
Unsung hero that can transform your body
To start, it’s helpful to understand more about how eating more fibre can help you transform your whole body’s health from the inside out. Most people think of the immune system as something that lives in the blood or the lymph nodes. In fact, up to 70 per cent of it is housed in the gut – a concentration that makes sense if you consider that the gut is one of the body’s primary checkpoints between the outside world and our inside one.
The microbes that populate our guts are, as the microbiologist Kiran Krishnan puts it, ‘the eyes and ears of our immune system’.
When they detect a threat – a harmful pathogen or foreign substance – they signal to immune cells to mount a response.
In this way, our beneficial microbes are actively involved in training and directing our immune system. However, the gut is only part of the picture: microbial communities also inhabit the mucous membranes lining the mouth, nose, eyes and lungs.
Taken together, these membranes create a microscopic protective shield covering a remarkable 372 sq m – and the beneficial microbes across all of them play a role in immune defence.
This is why dietary fibre matters more than any immunity-boosting superfood trend. Without enough of it, those microbial populations decline – and with them, our immune defences weaken, leaving us more susceptible to illness.
Get balance right between gut and brain
One of the body’s most important relationships is the intimate connection between the gut and the brain.
The two are in constant two-way communication via the vagus nerve – to the extent that problems in one area can be reflected in the other. Stress and anxiety can disrupt digestion, while inflammation or microbial imbalances in the gut can affect mood, memory and cognitive function, for instance.
A study of 1,430 adults found that specific gut microbes were associated with better brain health and that lower levels of these microbes correlated with cognitive decline and reduced volume in the hippocampus, the brain’s memory centre.
One microbe, Odoribacter, showed a strong association with brain volume. Odoribacter isn’t available in supplement form, it only thrives when fed the right foods in fibre-rich, plant-based meals.
According to a 2023 study, just 5g of additional fibre a day – roughly half an avocado’s worth – is associated with a 5 per cent lower likelihood of depression.
Reduce inflammation to fend off disease
Inflammation is the body’s built-in response to injury or infection, designed to protect tissue and promote healing.
It involves immune cells, blood cells and signalling molecules that rush to the affected area to clear damage. Essential in the short-term – to respond to a cut, say – it can wreak havoc if it becomes chronic and widespread. Reducing sources of inflammation is therefore one of the most powerful ways to stay well and fend off disease.
While we can’t change our genes, we can influence how they are expressed – and environment and lifestyle can account for 70-95 per cent of disease risk.
The gut can be a major source of inflammation in the body because its lining is surprisingly delicate – just one cell thick.
During digestion the gut naturally becomes more permeable to absorb nutrients but when that permeability increases too much – a condition known as ‘leaky gut’. It can allow harmful toxins, undigested food particles and bacterial fragments to enter the blood stream.
One key offender is lipopolysaccharide (LPS), a toxic compound released by some problematic gut bacteria. If LPS leaks through a weakened gut lining, it can spark widespread inflammation.
Over time, this has been linked to conditions including insulin resistance (where your body stops responding correctly to insulin, the hormone that clears excess glucose from your blood stream), brain fog, chronic fatigue and mood disorders.
One of the best ways to treat leaky gut is by eating high-fibre foods which support the production of short-chain fatty acids – compounds that strengthen the gut lining.
Conversely, diets high in ultra-processed foods and sugar can raise LPS levels, and disrupt the balance of the gut. There is even some research to suggest that certain harmful bacteria may be linked to Alzheimer’s disease.
However, the more fibre we eat, the more we feed our beneficial gut bacteria, which produce anti-microbial substances that keep ‘bad’ bacteria in check.
Maintain a healthy oral microbiome
The mouth is the beginning of the gut and home to almost 20 billion bacteria. The balance of this microbial community is shaped by the gut microbiome and the foods you eat, as well as how often you brush and floss.
Because oral bacteria also enter the bloodstream, maintaining a healthy oral microbiome can, over time, help reduce the inflammation that contributes to conditions such as heart disease, diabetes and Alzheimer’s.
Fast to boost your gut health
Narrowing your eating window to, say, 12 hours, and fasting for 12 hours can make a big difference to your gut health.
We naturally fast during our sleep cycle, so if you can, extend it slightly. Resting your gut for longer creates an environment where beneficial microbes can flourish. Not eating for two to three hours before you sleep allows for a more restful sleep too. Reaching for herbal teas instead of late night snacks is a game changer for your gut health.
We’ve long known that the Mediterranean diet is good for heart health, but research is now helping us understand why – and it’s partly thanks to the way fibre supports the gut.
Studies show that fibre-rich diets boost the release of butyrate – a short-chain fatty acid produced by beneficial bacteria – which in turn improves heart health.
A landmark study in the British Medical Journal (BMJ) found that fibre reduces the risk of heart disease, stroke, type 2 diabetes and colon cancer by 16-24 per cent.
In observational studies, those with higher-fibre diets had a 23 per cent lower risk of all cause mortality.
Control your blood sugar
Your gut microbes could influence the development of type 2 diabetes – and may even help predict who’s at risk.
A high-sugar diet can shift the balance of the gut in an unhealthy direction, fuelling the growth of harmful gut bacteria; levels of beneficial bacteria are often lower in people with prediabetes and type 2.
Interestingly, researchers have found that metformin – a commonly prescribed medication for type 2 diabetes – doesn’t just increase insulin sensitivity and help clear sugar from the bloodstream; it also boosts production of beneficial postbiotics, the beneficial chemicals made by gut bacteria when they digest fibre. These include short-chain fatty acids (SCFAs), enzymes and vitamins.
Nutrient boost is the key to longevity
Boosting your fibre intake could also mean living longer. One study showed that increasing fibre by 10g per 1,000 calories was linked to a reduction in biological age of more than four years.
Fibre may also help you age better. As we get older, the protective caps on our DNA (telomeres) shorten – but studies have shown that people who eat more fibre have longer telomeres, associated with healthier ageing.
Gut microbiome diversity also tends to decline with age, while inflammation increases.
Centenarians tend to have more youthful gut microbiomes – with greater diversity and beneficial anti-inflammatory bacteria – which may explain their longevity.
One study found that switching from a typical Western diet to a Mediterranean one – rich in whole grains, nuts, fruit and vegetables, and lower in sugar and processed meats – could increase life expectancy by up to ten years.
Even those in their 70s saw a potential gain of five years: proof it’s never too late to start.
Get skin conditions under control
Just like the gut, our skin is home to billions of bacteria, most of them helpful. When these microbial communities become unbalanced, it can affect the skin’s barrier, sometimes leading to redness, irritation or breakouts.
People with eczema often have fewer beneficial bacteria and certain gut microbes can drive particular skin conditions.
Helicobacter pylori, for example, has been identified as one possible driver of rosacea. Once resolved, eating more fibre can restore the balance by calming inflammation, supporting skin cell repair and strengthening the skin’s outer barrier – this protects against germs and dryness.
Balance hormones to get system in check
Gut health also shapes our hormones – including oestrogen, vital for menstrual and reproductive health. The oestrobolome, a group of gut microbes, helps regulate how oestrogen is processed and cleared from the body. After the liver breaks it down, oestrogen is sent to the gut to be eliminated.
An enzyme called beta-glucuronidase – often overproduced when the gut microbiome is unbalanced – can disrupt this process. This has been linked to oestrogen-related conditions such as endometriosis, fibroids, infertility and even hormone-related cancers.
A fibre-rich, varied diet that helps create a balanced microbiome is key to keeping this system in check – even during the menopause, when oestrogen levels change. A study involving more than 17,000 menopausal women found that those eating more fibre from fruit, vegetables and soy experienced a 19 per cent reduction in hot flushes.
Another study linked osteoporosis in post-menopausal women to lower gut diversity and more inflammatory bacteria.
