Everyone's been maxxing protein. Now your gut wants a turn.
Fibremaxxing has become one of 2026's big health trends, and unusually for an internet health trend, there’s a sensible idea underneath it. UK adults are advised to eat around 30g of fibre a day, yet the latestNational Diet and Nutrition Survey found adults aged 19–64 averaged just 16.4g, with only 4% meeting the recommendation.
Perhaps we don't need to “maxx” fibre. We just need to stop chronically undeeating it.
1. Fibre is having its protein moment
Protein has dominated the health world for years. Protein yoghurts, cereal, bars, everything. Meanwhile, fibre has quietly been left behind, despite doing far more than simply helping you poo.
Certain fibres reach your colon, where gut microbes ferment them and produce short-chain fatty acids such as acetate, propionate and butyrate. But different fibres interact differently with our microbiome, and research suggests the effects depend partly on the type, structure and dose of fibre. So smashing psyllium every day isn't necessarily equivalent to getting fibre from a variety of beans, vegetables, fruit, wholegrains, nuts and seeds.A systematic review of fibre, gut bacteria and short-chain fatty acids
Don't fibremaxx. Fibre-diversify.
2. But fibre isn't the whole story
This is where things get interesting. In aStanford randomised trial published in Cell, 36 healthy adults ate either a high-fibre or high-fermented-food diet for 10 weeks. You might expect the high-fibre group to come out as the microbiome champions, but that isn't quite what happened.
Microbial diversity didn't significantly increase in the high-fibre group during the study, and greater fibre intake led to more carbohydrates remaining in stool samples, suggesting incomplete breakdown. Meanwhile, the fermented-food group — eating foods including yoghurt, kefir, kimchi and kombucha — showed increased microbial diversity and reductions in several inflammatory markers.
The researchers suggested that people eating modern industrialised diets may have too few fibre-degrading microbes to immediately make use of a big increase in fibre, or simply need longer for their microbiome to adapt. Importantly, this doesn't prove fermented foods make you better at digesting fibre; the study didn't test the two together.
But it raises an interesting idea: gut health isn't just about what you feed your microbiome. It's also about who's sitting at the table.
3. Feed the microbes. Give them some company.
A simple way to think about it is that fibre provides food for your existing microbial ecosystem, while fermented foods can expose that ecosystem to microbes and compounds produced during fermentation.
They're different tools, and not every fermented food technically qualifies as a probiotic. Under the scientificconsensus definition of a probiotic, the specific live microorganisms must have demonstrated a health benefit.
The practical approach is simple: aim towards 30g of fibre a day, get it from a variety of plant foods, and regularly include fermented foods such as live yoghurt, kefir, kimchi, sauerkraut, miso and raw, unpasteurised kombucha.
Increase fibre gradually too. Going from 15g to 50g overnight is a very efficient way of discovering exactly how vocal your intestines can be.
The goal isn't to win fibre. It's to build a gut ecosystem that can actually make good use of it.
Health Hack: Most bang for your buck fibre
Psyllium husk ~85–95g fibre per 100g
Wheat bran ~43g
Cocoa powder ~37g
Chia seeds ~34g
Flaxseed ~27g
For everyday use, chia, flax and a little psyllium are probably the easiest wins. Add them to yoghurt, oats or smoothies and you've increased your fibre without completely changing what you eat.
Just increase gradually and drink enough water, or fibremaxxing may rapidly become toiletmaxxing.
