"Supplements designed for a body that doesn't exist."
Bloating. The kind that makes you unbutton your jeans by 2pm. The kind that makes you cancel plans because you don't know how your stomach will behave. The kind that's been going on for months — or years — despite your best efforts to fix it.
If this is familiar, you're far from alone. An estimated 6.7 million people in the UK live with irritable bowel syndrome, and the majority are women. The pattern is consistent: symptoms begin or worsen in the 40s, coinciding with hormonal changes that directly reshape the gut microbiome. The bloating, the unpredictable digestion, the fatigue after meals — these aren't imagined, and they're not simply a matter of eating the wrong things.
What most women don't know is that the gut microbiome — the community of bacteria living in your digestive tract — is as individual as a fingerprint. No two people have the same bacterial profile. Yet the vast majority of gut health products are formulated for a population-level average, not for any individual's specific biology.
This is the core problem. And it's why so many women spend years trying products that genuinely work for other people and do nothing for them. Our editorial team set out to find whether any product on the market addresses this — and to rank what's available against criteria that actually matter.
Five Criteria, Applied Identically
Each product was scored 0–10 on each criterion, then weighted into a single score out of 100. No product was assessed on criteria the others weren't.
Every Product, Reviewed the Same Way
Specification, overall score, criterion-by-criterion rating, assessment, and pros and cons — in that order, for all four entries.
Where an entry is beaten on a criterion, that is stated in its own review.
NB1 Personalised Gut Protocol
Score
Use this code at NB1 checkout
NB1FIRSTValid on 4- and 12-month plans only. Not available on the monthly rolling plan.
Symprove Liquid Probiotic
Score
Multi-Strain Probiotic Blends
Score
Generic Prebiotic & Fibre Supplements
Score
How the Top-Scoring Protocol Works
Because the highest-scoring entry works differently from a shelf supplement, we documented its process step by step.
Reports Sent to Our Editorial Inbox
Unverified reader accounts, published as received. Individual experiences vary.
"I'd tried four different probiotics over two years. My results showed why none of them worked — I was low in bacteria strains that aren't in any standard probiotic formula. Six weeks in, my morning bloating is gone."
"The sequencing report was unlike anything I'd seen. It wasn't a quiz or a survey — it was actual data showing which species were present in my gut and at what levels."
"I retest in two months and I'm genuinely looking forward to the numbers. I've never had a supplement I could actually measure before."
How They Compare
All four entries, every criterion, on one grid. The Best tag marks the leading result in each row.
| NB1 · #1 overall | Symprove | Multi-strain blends | Prebiotic fibre | |
|---|---|---|---|---|
| Overall score |
88 / 100
Best
|
56 / 100
|
44 / 100
|
30 / 100
|
| Root cause approach |
10 / 10
Best
|
5 / 10
|
5 / 10
|
2.5 / 10
|
| Personalisation |
10 / 10
Best
|
0 / 10
|
0 / 10
|
0 / 10
|
| Feedback mechanism |
10 / 10
Best
|
0 / 10
|
0 / 10
|
0 / 10
|
| Scientific backing |
7.5 / 10
|
8 / 10
Best
|
5 / 10
|
2.5 / 10
|
| Cost & accessibility |
4 / 10
|
7 / 10
|
8.5 / 10
|
9 / 10
Best
|
| No minimum commitment |
Yes
|
Yes
|
Yes
|
Yes
|
| Built from your own data |
Yes
Best
|
No
|
No
|
No
|
| Species-level sequencing |
Yes
Best
|
No
|
No
|
No
|
| Measurable retest |
Yes
Best
|
No
|
No
|
No
|
| Independent science board |
Yes
Best
|
Partial
|
No
|
No
|
| Typical monthly cost |
from £99
|
~£40
|
~£20
|
~£10
Best
|
The gut health supplement market is large and heavily marketed. Our testing found that most products operate on the same structural assumption: that one formula can serve all users. For women with chronic bloating and IBS-type symptoms who haven't responded to generic solutions, this assumption is the problem. Only one entry in this test treats the individual's biology — rather than a statistical average — as the starting point, and its combination of species-level sequencing, personalised protocol and measurable feedback loop places it in a different category from everything else we reviewed. It is not the winner on every measure. Symprove has the stronger published evidence base, and the cheapest entries in this test are dramatically easier on the wallet and carry no commitment. Anyone whose symptoms respond to a generic probiotic should use one. For the women this test was designed around — those for whom generic products have already failed — the higher cost buys the one thing the rest of the field cannot offer: a protocol built from their own data, and a number that shows whether it is working.
Use this code at NB1 checkout
NB1FIRSTValid on 4- and 12-month plans only. Not available on the monthly rolling plan.