Fibremaxxing: Why Gut Diversity and Butyrate Are the Real Goal
Originally sent to subscribers on 31 August 2025
Protein vs. Fibre: The New Mantra
“Protein is king.” That’s the mantra you hear in gyms. But there’s a new buzzword: fibremaxxing. While protein builds you, fibre fuels you—not directly, but by feeding the trillions of microbes that outnumber your own cells.
DATA
Where insight becomes impact
We’re eating far too little fibre. Average intake in the UK is 8–10 g/day, yet the recommended minimum is 30 g/day and the longevity sweet spot is closer to 40–50 g/day.
Fibre isn’t just about “regularity.” When it reaches your colon, microbes ferment it to produce butyrate. Butyrate keeps your gut lining sealed, calms your immune system, influences gene expression, stimulates BDNF (your brain’s growth factor) and protects against dementia. Low butyrate is like a city without a clean‑up crew—waste builds, systems falter.
The main butyrate‑producing bacteria include Faecalibacterium prausnitzii, Roseburia species, and Butyrivibrio fibrisolvens. But fibre alone isn’t enough; you need the right microbes waiting in your gut.
DEVICES
Track it to hack it
How do you know if you’re making butyrate?
Gut microbiome testing: The gold standard, showing how much butyrate you produce and whether you have the right bacteria. Seven out of ten recent tests I ran showed low butyrate and low populations of these microbes.
Continuous Glucose Monitor (CGM): Fibre before carbs flattens your glucose curve, improving fermentation conditions.
HRV monitors (Oura, Whoop): Emerging evidence links butyrate to improved vagal tone, so an HRV rise after gut interventions may indicate happier microbes.
Smart toilets and stool trackers: Yes, they exist; they can analyse gut metabolites.
DECISIONS
From knowing to doing
If you ask “How do I increase butyrate‑producing bacteria?” here’s what I recommend:
Diversity diet: Rotate fibres—leeks, onions, asparagus, oats, beans, flax, apples. Variety = microbial teamwork.
Resistant starch: Cooled potatoes, reheated rice, green bananas—rocket fuel for Roseburia and F. prausnitzii.
Polyphenols: Berries, green tea, olive oil encourage F. prausnitzii growth.
Avoid unnecessary antibiotics: They’re microbial bleach and wipe out butyrate producers.
Butyrate supplements? They help, but most oral butyrate doesn’t survive the stomach. You have to make it inside you.
Remember the risks: Low butyrate is linked to higher rates of colon cancer, irritable bowel, diabetes, and even depression.
Case in point
A client with afternoon fatigue and brain fog had very low Roseburia and F. prausnitzii. We focused on resistant starch and polyphenol‑rich foods. Six weeks later, these bacteria flourished, butyrate rose, and his energy and mood improved.
DIARY
Last week: Debut on ITV2’s Sam & Billie: Sister Act, and recorded a podcast on hot and cold therapies.
This week: On an equine retreat with my daughter.
Next week: Judging the Growing Business Awards for the third year.
DISTINCTION
“Feed your microbes and they'll feed your future”.
When was the last time you measured what your microbes actually make—not just what you’re eating?
Wishing you a wonderful week ahead!
Dr Alka