Fibre has long been hailed as the key to “keeping things moving”, but there’s so much more to this humble nutrient than regular bowel habits. Fibre is one of the most powerful tools for nourishing your gut microbiome, supporting immune health, regulating blood sugar, and even balancing hormones.
But not all fibre is created equal, and understanding the different types can help you optimise your gut health in a much more strategic way.
The Two Main Types of Fibre
- Soluble Fibre
- Dissolves in water to form a gel-like substance
- Helps slow digestion and stabilise blood sugar
- Sources: oats, flaxseeds, chia, apples, citrus fruits, legumes
- Feeds: beneficial bacteria like Bifidobacteria and Lactobacillus
- Insoluble Fibre
- Adds bulk to stool and helps speed up transit time
- Keeps the bowels regular
- Sources: whole grains, nuts, seeds, vegetable skins, celery, bran
- Not as fermentable, but important for mechanical gut health
A balanced diet includes both types; one to nourish your microbiome, the other to support physical motility and elimination.
Prebiotic Fibre: Microbiome Fuel
Certain types of fibre act as pre-biotics, meaning they specifically feed your beneficial gut bacteria, helping them thrive and crowd out unwanted pathogens.
Some key prebiotic fibres include:
- Inulin (from chicory, onions, garlic, leeks) – promotes growth of Bifidobacteria
- Fructooligosaccharides (FOS) – found in bananas, asparagus, Jerusalem artichokes
- Galactooligosaccharides (GOS) – found in legumes and also used in supplements
- Pectin (from apples, citrus, berries) – supports butyrate-producing bacteria
- Acacia Fibre – a gentle, soluble fibre that feeds Bifidobacteria and Lactobacillus, and is often well-tolerated by sensitive guts
- PHGG (Partially Hydrolysed Guar Gum) – shown to increase levels of Akkermansia muciniphila, a keystone bacteria involved in gut lining integrity, blood sugar balance, and metabolic health
These fibres are fermented by your gut microbes, who in turn produce beneficial compounds like short-chain fatty acids (SCFAs) — especially butyrate, which reduces inflammation, strengthens the gut barrier, and helps regulate the immune system.
Resistant Starch: The Forgotten Fibre
Resistant starch is a unique type of fermentable fibre that resists digestion in the small intestine and reaches the colon intact, where your microbes break it down and turn it into SCFAs.
There are several types:
- Type 1 – found in whole or partially milled grains and seeds
- Type 2 – raw potatoes, green bananas
- Type 3 – retrograded starch from cooked and cooled rice, potatoes, or oats
- Type 4 – man-made versions (often added to bars or supplements)
Resistant starch is especially good at increasing levels of butyrate, and supports bacteria like Ruminococcus bromii and Faecalibacterium prausnitzii, both linked to reduced inflammation and better gut barrier function.
Pro tip: try adding cold cooked potatoes, lentil salad, or green banana flour to your routine to get a fibre diversity boost.
Fibre Diversity = Microbiome Diversity
Your gut bacteria thrive on variety. Different fibres feed different bugs, so the more types you include, the more robust and balanced your microbiome becomes.
Aim for:
- 30+ plant foods per week – veggies and fruit, nuts, seeds, grains, legumes, herbs and spices, dark chocolate
- A mix of soluble, insoluble, prebiotic, and resistant starch
- A fibre upgrade across meals — chia pudding, lentils, roasted veg, cooled grains and starches, flax crackers, etc.
Fibre isn’t just roughage, it’s functional fuel for your gut ecosystem. It’s one of the simplest, most effective ways to support long-term gut health, hormonal balance, and immunity.
Want to learn more about how to work with and support your microbiome? Join me at my upcoming Gut Health Retreats in Gloucestershire, where we dive deep into food-as-medicine, learn the best ways to fuel our microbiome and enjoy a fibre-rich meal together.
👉 Find out more and book your place.
Fleur Wellness Co. 
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