Fibre and Gut Health: Why Everyone Is Suddenly Talking About Fibre
For the past few years, protein has managed to find its way into almost every corner of the supermarket. Protein yoghurt, protein cereal, protein bars, protein water and foods that never previously needed a protein claim now proudly displaying one across the packet.
But another nutrient is beginning to have its moment.
Fibre.
"Fibremaxxing" has emerged as one of the latest nutrition trends, encouraging people to deliberately increase the amount and variety of fibre they eat each day. Like most wellness trends, the name makes something we've known about for decades sound remarkably new.
But unlike many trends, there is actually a very good reason to be paying more attention to fibre.
Most Australians aren't eating enough of it.
And when we look beyond bowel regularity, fibre becomes much more interesting. It can influence the gut microbiome, blood glucose regulation, cholesterol, appetite, inflammatory signalling and metabolic health.
So while we may not need to "max" anything, perhaps fibre deserves considerably more attention than we've been giving it.
What is fibre?
Dietary fibre is the part of plant foods that isn't completely digested in the small intestine. Instead, it travels into the large intestine, where different types of fibre can perform different functions.
Insoluble fibre, found in foods such as wheat bran, whole grains, nuts, seeds and the skins of many fruits and vegetables, adds bulk to stool and helps support regular bowel movements.
Soluble fibre, found in foods including oats, barley, legumes, apples and citrus fruit, absorbs water and can form a gel in the digestive tract. This can help slow digestion and influence cholesterol and blood glucose responses.
Then there are fermentable and prebiotic fibres, including resistant starch, inulin and certain oligosaccharides. These are found across foods such as legumes, onions, garlic, leeks, slightly green bananas and cooked-and-cooled potatoes and can be fermented by bacteria living in the gut.
This is why talking about fibre as though it were one nutrient can be misleading. Different plant foods provide different combinations of fibre, and those fibres can have different effects throughout the digestive system.
Rather than focusing exclusively on a number of grams each day, diversity matters too.
How much fibre should Australians eat?
Australian dietary recommendations suggest adult women consume approximately 25 grams of fibre each day and adult men approximately 30 grams, although individual needs vary.
Many Australians don't consistently reach these levels.
One reason may simply be that modern diets contain fewer whole plant foods and more highly processed foods where much of the natural fibre has been removed.
This has created an interesting situation where fibre is now being added back into processed foods and marketed as a functional ingredient.
A high-fibre snack can certainly contribute towards daily intake, but that doesn't necessarily make it nutritionally equivalent to vegetables, legumes, whole grains, nuts, seeds and fruit.
Whole plant foods don't provide fibre in isolation. They also contain vitamins, minerals and thousands of plant compounds, including polyphenols and other bioactives.
The food matrix matters.
What does fibre do for the gut microbiome?
One of the reasons fibre has attracted renewed attention is our growing understanding of the gut microbiome, the enormous community of microorganisms living within the gastrointestinal tract.
Certain types of dietary fibre act as substrates for beneficial gut bacteria. When these fibres are fermented, bacteria produce compounds known as short-chain fatty acids, including butyrate, acetate and propionate.
Butyrate is particularly interesting because it provides an important energy source for cells lining the colon and is involved in maintaining intestinal barrier function and regulating immune and inflammatory activity.
This means the relationship between fibre and gut health isn't simply about "keeping you regular".
What we eat can influence which microorganisms thrive in the gut and what compounds those microorganisms subsequently produce.
Can fibre help reduce inflammation?
The relationship between fibre and inflammation is indirect but increasingly important.
Higher-fibre dietary patterns are generally associated with better metabolic and cardiovascular health and lower levels of several inflammatory markers. One potential mechanism involves the gut microbiome and the short-chain fatty acids produced when certain fibres are fermented.
These metabolites can interact with immune cells and influence inflammatory signalling throughout the body.
Fibre-rich diets also tend to contain greater quantities of plant polyphenols, which themselves interact with gut microorganisms and have antioxidant and anti-inflammatory properties.
It would therefore be overly simplistic to say that "fibre reduces inflammation". What appears more likely is that diets rich in diverse plant foods create a biological environment that better supports gut, metabolic and immune health.
What does fibre have to do with blood sugar?
Fibre can also influence the way we respond to carbohydrates.
Soluble fibre can slow gastric emptying and carbohydrate absorption, helping moderate the rise in blood glucose following a meal. Oats and barley are particularly useful sources because they contain beta-glucan, while legumes, apples, pears and citrus fruit also provide soluble fibre.
That doesn't mean every carbohydrate needs to be carefully engineered to prevent a glucose "spike". Blood glucose naturally rises after eating carbohydrates, and this is a normal physiological response.
What matters more is the overall dietary pattern.
Eating carbohydrates as part of meals containing fibre, protein and healthy fats generally produces a different metabolic response than consuming highly refined carbohydrates in isolation.
This becomes increasingly relevant as we age because maintaining metabolic health is an important component of long-term healthspan.
Fibre, the gut and healthy ageing
The gut microbiome changes throughout life, influenced by diet, medications, illness, environment, activity and ageing itself.
Researchers are increasingly interested in how microbiome diversity and the metabolites produced by gut bacteria may influence healthy ageing, immune function and chronic disease risk.
Again, there is no single "longevity microbiome" we can simply create by eating more fibre.
But dietary diversity appears to matter.
Rather than relying on the same few high-fibre foods every day, think across different plant groups: lentils or chickpeas, oats or barley, almonds or pistachios, chia or flaxseed, berries, pears, avocado, leafy greens, broccoli, onions and root vegetables.
Each brings a slightly different combination of fibres, polyphenols and other plant compounds to the diet.
This is one reason we prefer to think about plant diversity rather than individual superfoods.
Your gut bacteria don't need the latest exotic ingredient. They need variety.
Is fibremaxxing actually a good idea?
This is where a useful nutrition message can become unnecessarily extreme.
If fibremaxxing means consciously including more vegetables, legumes, whole grains, nuts, seeds and fruit in your diet, there is plenty to like about it.
If it means suddenly doubling your fibre intake because you've seen someone consuming 50 grams a day online, that's less sensible.
Increasing fibre too quickly can cause bloating, gas and gastrointestinal discomfort, particularly in people who aren't accustomed to eating large amounts of it. Certain gastrointestinal conditions may also require individualised dietary advice.
Fibre intake is generally better increased gradually alongside adequate fluid intake.
There is also no particular prize for eating the most fibre.
More isn't automatically better. Enough, consistently, from a diverse range of foods is a much more useful goal.
Do you need a fibre supplement?
For most people, food is a very good place to start.
Legumes, vegetables, fruit, whole grains, nuts and seeds provide fibre alongside a complex mixture of micronutrients and plant bioactives that isolated fibre supplements don't necessarily replicate.
Fibre supplements can certainly have a role in particular circumstances and some types have good evidence for specific health outcomes, but they shouldn't automatically be the first response to a low-fibre diet.
Before adding another supplement, it may be worth asking a much simpler question:
How many different plants have I eaten this week?
What does fibre have to do with STMNA?
Fibre and plant bioactives are different things, but they share an interesting relationship.
Many of the foods that naturally contain fibre also contain polyphenols and other plant bioactive compounds. These compounds interact with our cells, our gut microbiome and the biological pathways involved in oxidative stress and inflammation.
This is one of the reasons plant diversity is so consistently associated with healthy dietary patterns.
STMNA Bioactives Healthspan isn't designed to replace those foods. Quite the opposite.
Our approach has always been that concentrated plant bioactives should sit alongside the foundations of health: a diverse diet, regular movement, good sleep and appropriate recovery.
Supplements should supplement. It's right there in the name.
Maybe fibre didn't need a rebrand
There is something slightly amusing about watching fibre become fashionable.
For decades, we've known that vegetables, legumes, fruit, nuts, seeds and whole grains are good for us. Now we've given eating more of them a hashtag.
But if fibremaxxing encourages people to eat a greater variety of whole plant foods, perhaps that's one wellness trend worth keeping.
We just don't need to turn it into another competition.
You don't need the highest fibre score.
You don't need to completely rebuild your diet tomorrow.
And you probably don't need another product promising to fix your gut.
Eat more plants. Eat different plants. Give your gut something worth working with.
Sometimes the least fashionable health advice has a remarkable habit of surviving every trend that comes after it.
Frequently Asked Questions About Fibre
How much fibre should women eat per day?
Australian recommendations suggest adult women aim for approximately 25 grams of dietary fibre per day, although individual requirements can vary.
What foods are highest in fibre?
Some particularly fibre-rich whole foods include legumes such as lentils, chickpeas and beans; seeds such as chia and flaxseed; whole grains including oats and barley; nuts such as almonds and pistachios; and fruits including raspberries, pears and avocado.
Rather than looking for one "highest-fibre" food, it can be more useful to combine different sources throughout the day because they provide different types of fibre. Oats and barley are rich in beta-glucan, legumes provide soluble, insoluble and fermentable fibres, chia and flaxseed provide soluble and insoluble fibre, while foods such as slightly green bananas and cooked-and-cooled potatoes can provide resistant starch.
The goal isn't simply more fibre. It's more variety in the fibre you eat.
Is fibre good for gut health?
Certain fibres can be fermented by gut bacteria and contribute to the production of short-chain fatty acids such as butyrate, which plays a role in intestinal and immune health.
Can eating more fibre help inflammation?
Higher-fibre dietary patterns are associated with better metabolic health and lower inflammatory markers, although fibre is only one component of the overall diet.
What is fibremaxxing?
Fibremaxxing is a social media nutrition trend focused on deliberately increasing daily fibre intake. The basic principle can be beneficial, but fibre should generally be increased gradually rather than maximised unnecessarily.
Can you eat too much fibre?
Very high fibre intake, particularly when increased suddenly, can cause bloating, gas and gastrointestinal discomfort. Individual tolerance and medical conditions also need to be considered.
