Fibermaxxing became a genuine trend in 2025 for good reason — most people in the UK consume less than half the recommended daily fibre intake. But not all fibre feeds your microbiome equally. Prebiotic fibres are a specific subset that selectively feed beneficial bacteria. Here's what actually has evidence behind it.
Organic Acacia Senegal Fibre Powder
Soluble Prebiotic FibreAcacia fibre is the standout prebiotic for sensitive guts. Its slow fermentation rate means it feeds beneficial bacteria gradually along the entire length of the colon rather than fermenting rapidly in the upper gut and causing gas. It specifically supports Bifidobacterium and Lactobacillus populations and has evidence for feeding Akkermansia — the strain associated with gut barrier integrity. Completely tasteless and dissolves invisibly in any liquid.
Pros
- Slow fermentation means minimal bloating even at higher doses
- Specifically feeds Akkermansia — the gut barrier integrity strain
- Completely tasteless and dissolves invisibly in any drink
Cons
- Higher cost per gram than most fibre supplements
- Benefits take weeks of consistent daily use to become measurable
Chicory Root Inulin Powder (FOS 95%+)
Inulin / FructooligosaccharidesInulin is the most researched prebiotic fibre type and the one with the broadest evidence base for increasing Bifidobacterium populations. Chicory-derived inulin at 95%+ FOS purity is the most bioavailable form. The caveat is its fast fermentation rate — starting too high too quickly causes significant gas and bloating. Start at 3g daily and increase slowly over several weeks. Not recommended as a first prebiotic if you have a history of IBS.
Pros
- Most extensively researched prebiotic type globally
- Strong evidence for increasing Bifidobacterium populations
- Excellent value — very low cost per gram
Cons
- Fast fermentation causes significant bloating if dosed too quickly
- Not recommended for IBS sufferers as a starting point
Unmodified Potato Starch (Resistant Starch RS2)
Resistant StarchResistant starch is the most underrated prebiotic — and unmodified potato starch is one of the cheapest and most concentrated sources available. RS2 starch resists digestion in the small intestine entirely, arriving in the colon intact where it preferentially feeds Butyrivibrio and other butyrate-producing species. Butyrate is the primary fuel source for colonocytes — the cells lining your gut wall. Start with a teaspoon in cold water and build up slowly.
Pros
- Feeds butyrate-producing bacteria — key for gut wall health
- Exceptional value — one of the lowest cost prebiotics per gram
- Feeds different bacterial populations than inulin or acacia
Cons
- Must be consumed cold — heat converts RS2 to digestible starch
- Chalky texture in water — mixes better into smoothies or yoghurt