One bottle. Millions of different guts.
Most brands ship the same fixed blend to everyone. But colonization depends on the ecosystem already inside you. A formula made for an average gut is still a guess in yours.
Backed by Y Combinator
The accelerator behind Airbnb & Stripe
Personalized probiotics, matched to your gut.
Test your microbiome. Get a formula made for your gut. Retest at 90 days to see what changed.
90-day money-back guarantee · Cancel anytime
Personalized probiotics, matched to your gut
A personalized probiotic is a probiotic formula matched to your own gut microbiome, chosen from a test of the bacteria you actually have rather than a one-size-fits-all blend. GutGutGoose makes one just for you: it starts with a simple gut test at home, we sequence your microbiome, match probiotic strains to what your gut is missing, and compound your formula fresh, then retest and refine every 90 days. Backed by Y Combinator, with a 90-day money-back guarantee.
Science
Scientists map every bacterium, use a supercomputer to build a virtual copy of your gut, run millions of simulations, then compound probiotics engineered to actually work inside you.
Your gut affects more than you think. Here's where you may feel it.
[01]“I get bad bloating.”
Bloating / distension
By afternoon, your stomach feels tight, swollen and uncomfortable.
How we help: We prioritise strains studied for persistent bloating and track how often it happens.
Across 26 trials, multi-strain formulas, including combinations using L. paracasei, L. acidophilus and B. lactis, reduced the relative risk of persistent bloating by 25%. Goodoory et al. 2023
[02]“I was in agony… just from wind pain.”
Abdominal pain / discomfort
Sharp, trapped pain makes sitting, sleeping and concentrating difficult.
How we help: We select strains studied for abdominal pain and track its frequency and intensity.
Across 32 trials, multi-strain formulas reduced the relative risk of persistent abdominal pain by 28%. The review also found strain-level signals involving L. plantarum, B. bifidum and S. cerevisiae. Goodoory et al. 2023
[03]“Foods I used to eat suddenly started causing discomfort.”
Food-triggered reactions
Your safe-food list keeps shrinking. Every meal feels like another experiment.
How we help: Your diet, symptoms and metabolic pathways help determine the strains and doses in your formula.
Food reactions can have many causes. GutGutGoose does not diagnose or treat food allergies.
[04]“I just want to stop having diarrhoea every day.”
Diarrhea / loose stools
Long drives, meetings and unfamiliar places all require bathroom planning.
How we help: We select around your bowel pattern and track stool form, frequency and urgency.
Formulas containing L. acidophilus and E. faecalis strains were associated with approximately four fewer bowel movements per week. A studied S. cerevisiae strain produced stools 1.24 points firmer on the Bristol Stool Scale. Xie et al. 2023
[05]“It’s not predictable.”
Irregular bowel movements
The same meal feels fine one day and causes pain, bloating or urgency the next.
How we help: We establish your baseline and retest at 90 days, then use the results to refine your next formula.
[06]“I’m always very gassy.”
Gas / wind
You avoid foods and situations but still cannot predict when it will happen.
How we help: We focus on the bloating and pain surrounding gas, then measure each symptom separately.
Studies have evaluated formulas containing Lactobacillus, Bifidobacterium and Saccharomyces strains, but results for gas remain mixed. Niu et al. 2020 · McFarland et al. 2021
[07]“Super tired… very low energy.”
Fatigue / low energy
You sleep, but still wake up feeling drained.
How we help: We track energy separately and consider relevant strains when your evidence and health profile support them.
A studied B. longum strain improved self-reported energy and vitality after eight weeks. Patterson et al. 2024
[08]“When my gut flares, my anxiety follows.”
Mood / anxiety / stress
Symptoms begin, then so does the worry about food, bathrooms and leaving home.
How we help: We track gut-specific anxiety alongside your physical symptoms.
A three-strain formula containing two L. plantarum strains and P. acidilactici improved IBS quality of life and gut-specific anxiety. Lorenzo-Zúñiga et al. 2014
[09]“Wait… what was that thought?”
Cognitive problems / brain fog
You reread sentences, lose your train of thought or struggle to find the word.
How we help: We track mental clarity as a secondary outcome.
A studied L. plantarum strain improved objective recall and learning after 12 weeks. Evidence for IBS-related brain fog remains early. Önning et al. 2023
[10]“My skin’s flared up, it’s all over.”
Skin symptoms
Your skin changes alongside your gut, but you cannot tell whether the two are connected.
How we help: We track skin symptoms separately when they are part of your goal.
A three-strain formula containing B. longum, B. lactis and L. rhamnosus improved psoriasis severity when used alongside topical treatment. This evidence applies to diagnosed plaque psoriasis, not everyday rashes. Navarro-López et al. 2019
Your symptoms choose the target. Your biology shapes the formula.
We select. We dose. We measure. We refine.
Why most probiotics
let you down
You weren't the problem. The bottle was made without knowing your gut, and never checked after you took it.
Most are gone within 48 hours.
When bacteria cannot find a compatible niche, they pass through before they can settle in. We match strains to your microbiome to give them somewhere to take hold.
50 billion can still do nothing.
A huge CFU count cannot rescue the wrong strains. We choose the bacteria and dose together from your test, not the biggest number on a label.
Most brands stop at the bottle. We test again.
At day 90, we compare your microbiome with its baseline to see what colonized and what changed.
No colonization or no felt difference? Your money back.
1
/
4
GutGutGoose
vs. regular
probiotics.
Most probiotics ask you to trust the label. We build from your data, then test whether it worked.
| GutGutGoose | Generic probiotic | |
|---|---|---|
| Built for your gut | Same blend for everyone | |
| Strains selected for you | Popular standard strains | |
| 16× greater average colonization* | Often passes through | |
| Your specific health goals | General “gut health” | |
| Includes only ingredients tailored for you | May include ingredients that make your gut feel worse | |
| 31x longer-lasting* | Often short-lived | |
| Dose tailored to you | Fixed dose | |
| Designed around your diet | Ignores what you eat | |
| Results can be measured | No follow-up | |
| Evolves with your gut | Formula never changes |
*Beta-cohort result; publication pending. Better colonization and washout may enable longer activity but as this is a first of its kind product has not been extensively studied.
Personalised
One formula.
Six layers of evidence.
Model-guided from your microbiome, diet, health profile, medications, previous response and more, not picked from a menu.
Model guided
One formula.
Built around you. Not picked from a menu.
Built around you. Not picked from a menu.
Colonization fit
Which candidate strains have a compatible niche and the best chance to take hold in your gut.
Your microbiome
Every strain and microbial function we detect in your sample. This is the raw map behind your formula.
Metabolic pathways
Which pathways are active in your gut and which functions your formula is built to support.
Your real diet
The foods you actually eat, not an idealized meal plan.
Health & medications
Your medical history, goals, medications and supplements shape what we select and leave out.
Your previous response
For later formulas, your last GutGutGoose formula and retest show what to keep or change.
Two ways to
understand your gut.
Start with advanced gut testing, or apply for our full Personalized Probiotics service.
Advanced gut testing
$50/mo
Launch price
- Find out the bacteria, viruses, fungi and parasites in your gut and what they do
- Unlimited diet analysis through advanced biological modeling
- Know what impact food has on the bacteria in your gut and symptoms
- Mathematical recommendations on dietary replacements that won’t make you feel as bad
- $500 in testing value and first-of-its-kind dietary recommendation modeling
- 400–700 functional pathways analyzed
- 500,000–2,000,000+ unique microbial genes detected and analyzed
- 10,000–20,000 functional gene families analyzed
Personalized probiotic
$200/mo
Launch price until September 1st
The world’s most advanced gut modeling technology, designed to understand, predict and engineer your microbiome with a personalized probiotic.
- Application-only service with a 40% acceptance rate
- Limited enrollment with a dedicated specialist guiding you throughout your journey
- Full refund if your application is declined, testing shows we can’t help, or you’re not satisfied after 90 days
- Target specific symptoms with bacteria mathematically selected for your microbiome, medical history and physiology
- Three-stage safety review by Oxford PhDs and pharmacologists, with FDA-licensed compounding
- 90-day symptom relief guarantee: if you’re not completely satisfied, you’ll receive a full refund
YC founder? Get 50% off your first month, $100, then $200/month.
Verify and claim it here.
Longitudinal research
Every retest adds to a bigger picture.
Every longitudinal datapoint from your 20-million-read shotgun metagenomic stool test moves the research forward: studying whether microbiome patterns could one day help flag Alzheimer’s disease and dementia earlier than conventional diagnostics.
People behind the proof
The people who check our work: gut researchers, lab scientists, pharmacists and doctors who care about proof, not hype.
Scientific advisor
Dr Robin Mihrshahi
Sir William Dunn School of Pathology, University of Oxford
“There is hardly any condition that isn’t significantly affected by our gut biome.”
Pharmacology
Dr Bella Molaee
PhD Pharmacology
“These strains are selected to thrive in each specific gut ecosystem.”
Clinical advisor
Dr Bijan Mojarrabi
Clinical and compounding advisor
“A better, more ethical and more scientific direction for wellness.”
In the press
Personalized probiotics, in the news.
Independent journalists and universities have covered our work on personalized probiotics, and Y Combinator backs it.
Book a consultation
Meet with
our team.
Schedule a focused conversation about microbiome testing, personalized formulas, clinic partnerships, or research collaboration.
- Length10 minutes
- FormatPrivate video call
- WithA GutGutGoose team member
