Fibre & Gut Health: How Fibre Supports Your Gut Microbiome
“Fibremaxxing” has become a popular nutrition trend on social media. It involves deliberately eating more high-fibre foods in an effort to improve gut health.
Increasing your fibre intake can be beneficial—but more is not always better. Eating too much fibre too quickly can cause bloating, gas, abdominal discomfort and changes in bowel habits.
So, how much fibre do you need, which foods contain it and what does fibre actually do for your gut microbiome? Let’s take a closer look.
What is dietary fibre?
Fibre is a type of carbohydrate found naturally in plant foods. Unlike many other carbohydrates, fibre is not completely digested in the small intestine.
Instead, it travels into the large intestine, where different types of fibre perform different roles. Some add bulk to stools, while others are fermented by gut bacteria.
During fermentation, certain gut bacteria produce compounds called short-chain fatty acids. These compounds help support the cells lining the bowel and contribute to a healthy gut environment.
A fibre-rich diet is also associated with a lower risk of several chronic health conditions, including cardiovascular disease, type 2 diabetes and bowel cancer.
What is fibremaxxing?
Fibremaxxing is the practice of deliberately increasing dietary fibre by prioritising high-fibre foods at meals and snacks.
Unlike many social media nutrition trends, this one has some merit. Many Australians would benefit from eating more vegetables, fruit, wholegrains, legumes, nuts and seeds.
However, fibremaxxing should not become a competition to consume as much fibre as possible.
Your goal should be to meet your individual needs through a varied and balanced diet—not to chase an unnecessarily high fibre target.
How does fibre support your gut microbiome?
Your gut microbiome is the community of bacteria and other microorganisms living in your digestive system.
Some types of fibre act as a food source for beneficial gut bacteria. These fibres are sometimes described as prebiotic fibres.
Regularly eating a variety of plant foods can expose your gut bacteria to different types of fibre and plant compounds. This is one reason dietary variety is just as important as the total number of grams you eat.
Foods containing fermentable or prebiotic fibres include:
Onions, garlic and leeks
Legumes such as lentils and chickpeas
Oats and barley
Slightly green bananas
Cooked and cooled potato, rice and pasta
Asparagus
Nuts and seeds
You do not need expensive powders, supplements or commercial microbiome testing to start supporting your gut health. For most people, a varied, fibre-rich diet is an excellent place to begin.
What are the different types of fibre?
Fibre is often divided into soluble and insoluble fibre. Many plant foods contain a combination of both, so variety is key.
Soluble fibre
Soluble fibre absorbs water and can form a gel-like substance in the digestive tract.
It may help:
Support healthy cholesterol levels
Manage blood glucose levels
Promote fullness after eating
Feed beneficial gut bacteria
Soften stools and support comfortable bowel movements
Good sources of soluble fibre include oats, barley, beans, lentils, chia seeds, berries, apples and carrots.
Beta-glucan, a type of soluble fibre found in oats and barley, has particularly good evidence for helping reduce LDL cholesterol when consumed regularly as part of a balanced diet.
Insoluble fibre
Insoluble fibre adds bulk to stools and helps food and waste move through the digestive system.
Good sources include:
Wholegrain breads and cereals
Wheat bran
Brown rice
Nuts and seeds
Fruit and vegetable skins
Both soluble and insoluble fibre have important roles in supporting digestive health.
How much fibre do you need each day?
The Australian adequate intake recommendations for adults are:
Women: 25 grams per day
Men: 30 grams per day
Individual requirements may vary depending on your age, health, activity level, appetite and digestive symptoms.
Pregnancy, breastfeeding, gastrointestinal conditions, previous bowel surgery and certain medications may also affect the amount or type of fibre that is appropriate for you.
Why do people struggle to eat enough fibre?
Common reasons include:
Not eating enough fruit and vegetables
Choosing refined grains instead of wholegrain options
Eating legumes infrequently
Having a low intake of nuts and seeds
Relying heavily on highly processed, low-fibre foods
Following unnecessarily restrictive diets
The good news is that small changes can make a meaningful difference.
Easy ways to eat more fibre
Try making one or two changes at a time:
Add berries, chia seeds or nuts to breakfast
Choose wholegrain bread instead of white bread
Swap refined cereal for oats or a higher-fibre cereal
Add lentils or beans to soups, curries and pasta sauces
Include a piece of fruit with a snack
Leave edible skins on fruit and vegetables
Add extra vegetables to lunch and dinner
Snack on nuts, seeds, roasted chickpeas or wholegrain crackers
Include a variety of different plant foods across the week
Increasing your fibre gradually gives your digestive system and gut bacteria time to adjust.
Can you eat too much fibre?
Yes. Rapidly increasing your fibre intake can cause:
Bloating
Gas
Abdominal discomfort or cramping
Constipation or diarrhoea
Feeling excessively full
These symptoms are more likely when fibre intake increases suddenly or fluid intake is inadequate.
Very high-fibre diets can also make it difficult for some people to eat enough energy, protein and other nutrients. This may be particularly important for children, older adults, athletes and people with poor appetite or unintentional weight loss.
Certain gastrointestinal conditions may also require an individually tailored approach. If fibre consistently worsens your symptoms, simply adding more may not be the right solution.
Do fibre supplements improve gut health?
Fibre supplements such as psyllium can be useful in some circumstances, particularly for managing constipation or helping lower cholesterol.
However, a supplement usually provides only one or a small number of fibre types. Whole plant foods also provide vitamins, minerals and beneficial plant compounds.
Fibre supplements are best used for a specific reason rather than as a replacement for a varied diet. Speak with your dietitian or healthcare professional before starting a supplement if you have ongoing digestive symptoms, take regular medication or have a gastrointestinal condition.
The takeaway
You do not need to “fibremaxx” to support a healthy gut.
Focus on gradually including a variety of wholegrains, vegetables, fruit, legumes, nuts and seeds. Increase your intake slowly and drink enough fluid throughout the day.
A simple formula to remember is:
More plant variety + gradual increases + adequate fluid = a happier gut.
Frequently asked questions
What foods are highest in fibre?
Legumes, wholegrains, nuts, seeds, vegetables and fruit are all valuable sources. Beans, lentils, chickpeas, chia seeds, oats, bran cereals, berries, pears and avocados are particularly fibre-rich options.
Should I increase fibre if I am bloated?
Not always. Some types of fibre can worsen bloating in people with irritable bowel syndrome or other gastrointestinal conditions. A dietitian can help identify which foods and fibre types are best tolerated.
How quickly should I increase my fibre intake?
Increase your intake gradually over several days or weeks rather than making a dramatic change overnight. Introduce one or two higher-fibre foods at a time and ensure you are drinking enough fluid.
Is soluble or insoluble fibre better?
Neither is universally better. They have different functions, and most people benefit from eating a variety of foods containing both types.
Does fibre help with constipation?
Fibre can support bowel regularity, but the type of fibre matters. Increasing fibre without adequate fluid—or using the wrong type for your symptoms—may make constipation or discomfort worse.
At Health Management Dietitians, we can help tailor your nutrition to your symptoms, preferences and nutritional needs — helping you eat as comfortably and confidently as possible while reducing the risk of nutritional deficiencies.
We understand that nutrition isn’t one-size-fits-all. Our Cairns, Atherton and Mareeba dietitians provide personalised, practical nutrition advice to help you reach your goals while still enjoying food.