---
title: "Blue poo toilet test probes links between digestion speed and brain function"
id: "bmj-3-x201c-blue-poo-x201d-could-reveal-links-between-gut-and-brain-function-say"
canonical_url: "https://medichelpline.com/clinical-feed/bmj-3-x201c-blue-poo-x201d-could-reveal-links-between-gut-and-brain-function-say"
content_type: "clinical_feed_article"
specialty: "Gastroenterology"
source_name: "BMJ"
source_url: "http://www.bmj.com/content/395/bmj-2026-101163.short?rss=1"
published_at: "2026-10-21T09:06:13.000Z"
evidence_level: "Journal Feed"
license: "CC-BY-NC-4.0 / Informational Use"
---
# Blue poo toilet test probes links between digestion speed and brain function
## Provenance & Clinical Metadata
- **Canonical URL:** https://medichelpline.com/clinical-feed/bmj-3-x201c-blue-poo-x201d-could-reveal-links-between-gut-and-brain-function-say
- **Specialty:** [Gastroenterology](https://medichelpline.com/clinical-feed/gastroenterology.md)
- **Primary Source:** BMJ
- **Source URL:** [Original Journal Publication](http://www.bmj.com/content/395/bmj-2026-101163.short?rss=1)
- **Published At:** 2026-10-21T09:06:13.000Z
- **Evidence Rating:** Journal Feed
## Executive GIST (TL;DR)
- Researchers at the **University of Southampton** developed a simple home-based toilet test using an edible muffin with blue dye to time gut transit; participants track when their stool first turns blue. - Once a participant’s stool turns blue, the protocol asks them to complete online cognitive tasks; the aim is to compare gut transit time with measures of reaction speed and task performance. - The project seeks to explore associations between rapid intestinal transit and accelerated cognitive responses, suggesting a possible gut–brain functional relationship. - The brief report did not provide detailed trial methodology: the source did not report sample size, eligibility criteria, muffin composition beyond blue dye, dye dose, validated cognitive tests used, or statistical analysis plans. - Investigators framed the procedure as a low-cost, noninvasive way to measure whole-gut transit in free-living volunteers and to pair that physiological measure with online cognitive assessments. - Data collection appears participant-driven (self-timed stool colour change and online gaming), but the article did not report quality-control measures, blinding, or how confounders such as diet, medication, or circadian effects would be handled. - The news piece described the project aim and practical mechanics of the toilet test, and noted the intended link to thinking speed; the source did not report results, interim data, or timelines for findings publication.
## Clinical Analysis & Structured Key Points
[Skip to main content](https://www.bmj.com/content/395/bmj-2026-101163.short?rss=1#main-content) Intended for healthcare professionals * [Subscribe](https://www.bmj.com/us/subscribe) * [ My Account ](https://www.bmj.com/content/395/bmj-2026-101163.short?rss=1) * [My email alerts](https://myaccount.bmj.com/myaccount/account/hw-registration.html) * [BMA member login](https://bmjverification.bma.org.uk/validate/userdetails?url=https://www.bmj.com/content/395/bmj-2026-101163?rss=1&variant=short&sso=) [ Login ](https://www.bmj.com/content/395/bmj-2026-101163.short?rss=1) * Username * Password * [Forgot your log in details?](https://www.bmj.com/user/password "Retrieve your credentials.") [Need to activate](https://journals.bmj.com/cgi/activate/basic) * * * [BMA Member Log In](https://bmjverification.bma.org.uk/validate/userdetails?url=https%3A//www.bmj.com/content/395/bmj-2026-101163%3Frss%3D1%26variant%3Dshort%26sso%3D "Log in here if you are a BMA member.") [Log in via OpenAthens](https://openathens-sp.highwire.org/session/init?entityID=https%3A//idp.eduserv.org.uk/openathens&subcode=bmjjournals&hw-shib-return-uri=https%253A%252F%252Fwww.bmj.com%252Fcontent%252F395%252Fbmj-2026-101163.short%253Frss%253D1) [Log in via your institution](https://www.bmj.com/login/shibboleth?uri=https%3A%2F%2Fwww.bmj.com%2Fcontent%2F395%2Fbmj-2026-101163%3Frss%3D1&subcode=bmjjournals&env=prod) Edition: [ US ](https://www.bmj.com/content/395/bmj-2026-101163.short?rss=1) * [UK](https://www.bmj.com/bmj_countries/switch/uk?destination=node/1129160%3Frss%3D1%26variant%3Dshort) * [South Asia](https://www.bmj.com/bmj_countries/switch/india?destination=node/1129160%3Frss%3D1%26variant%3Dshort) * [International](https://www.bmj.com/bmj_countries/switch/international?destination=node/1129160%3Frss%3D1%26variant%3Dshort) [Our company](https://www.bmj.com/company?int_source=tbmj&int_medium=header&int_campaign=URLswitch) [ Toggle navigation ](https://www.bmj.com/content/395/bmj-2026-101163.short?rss=1) [ The BMJ logo ](https://www.bmj.com/ "Home") [Site map](https://www.bmj.com/sitemap) [Search](https://www.bmj.com/content/395/bmj-2026-101163.short?rss=1 "Search") ## Search form Search Search * [Advanced search](https://www.bmj.com/search/advanced "Advanced search") * [Search responses](https://www.bmj.com/rapid-responses "Search responses") * [Search blogs](https://blogs.bmj.com/bmj/ "Search blogs") [ Toggle top menu ](https://www.bmj.com/content/395/bmj-2026-101163.short?rss=1) * [Research](https://www.bmj.com/us/research) * [At a glance](https://www.bmj.com/us/research) * [Research papers](https://www.bmj.com/us/research/research) * [Research methods and reporting](https://www.bmj.com/us/research/research%20methods%20%26amp%3B%20reporting) * [Minerva](https://www.bmj.com/us/research/minerva) * [Education](https://www.bmj.com/us/education) * [At a glance](https://www.bmj.com/us/education) * [Clinical reviews](https://www.bmj.com/us/education/clinical%20review) * [Practice](https://www.bmj.com/us/education/practice) * [Minerva](https://www.bmj.com/us/education/minerva) * [Endgames](https://www.bmj.com/us/education/endgames) * [State of the art](https://www.bmj.com/specialties/state-art) * [What your patient is thinking](https://www.bmj.com/specialties/what-your-patient-thinking) * [Rapid recommendations](https://www.bmj.com/rapid-recommendations) * [Student](https://www.bmj.com/student) * [News & Views](https://www.bmj.com/us/news) * [At a glance](https://www.bmj.com/us/news) * [News](https://www.bmj.com/us/news/news?category=News) * [Features](https://www.bmj.com/us/news/feature) * [Editorials](https://www.bmj.com/us/news/editorial) * [Analysis](https://www.bmj.com/us/news/analysis) * [Opinion](https://www.bmj.com/news/opinion) * [Head to head](https://www.bmj.com/us/news/head%20to%20head) * [Editor's choice](https://www.bmj.com/us/news/editor%27s%20choice) * [Letters](https://www.bmj.com/us/news/letter) * [Obituaries](https://www.bmj.com/us/news/obituary) * [Careers](https://www.bmj.com/careers-articles) * [Rapid responses](https://www.bmj.com/rapid-responses) * [Campaigns](https://www.bmj.com/campaigns) * [At a glance](https://www.bmj.com/campaigns) * [Better evidence](https://www.bmj.com/better-evidence) * [Climate change](https://www.bmj.com/campaign/climate-emergency) * [Divestment from fossil fuels](https://www.bmj.com/divestment) * [Patient and public partnership](https://www.bmj.com/campaign/patient-partnership) * [Too much medicine](https://www.bmj.com/too-much-medicine) * [Wellbeing](https://www.bmj.com/wellbeing) * [The BMJ Collections](https://www.bmj.com/content/bmj-collections) * [Jobs](https://www.bmj.com/careers) * [Doctor Jobs UK](https://www.bmj.com/careers) * [Hospital Jobs UK](https://www.bmj.com/careers/jobs/hospital/) * [GP Jobs UK](https://www.bmj.com/careers/jobs/general-practice/) * [International Jobs](https://www.bmj.com/careers/jobs/international/) * [Archive](https://www.bmj.com/archive) * [For authors](https://www.bmj.com/about-bmj/resources-authors) * [Hosted](http://hosted.bmj.com) 1. [News & Views](https://www.bmj.com/us/news) 2. “Blue poo” could... 3. “Blue poo” could reveal links between gut and brain function, say scientists News # “Blue poo” could reveal links between gut and brain function, say scientists BMJ 2026; 395 doi: (Published 21 October 2026) Cite this as: BMJ 2026;395:e101163 * [Article](https://www.bmj.com/content/395/bmj-2026-101163 "Article Tab - Article")[](https://www.bmj.com/panels_ajax_tab/jnl_bmj_tab_art/node:1129160/1 "Article Tab - Article") * [Related content](https://www.bmj.com/content/395/bmj-2026-101163/related "Article Tab - Related Articles")[](https://www.bmj.com/panels_ajax_tab/jnl_bmj_tab_related_art/node:1129160/1 "Article Tab - Related Articles") * [Metrics](https://www.bmj.com/content/395/bmj-2026-101163/article-info "Article Tab - Info & Metrics")[](https://www.bmj.com/panels_ajax_tab/jnl_bmj_tab_info/node:1129160/1 "Article Tab - Info & Metrics") * [Responses](https://www.bmj.com/content/395/bmj-2026-101163/rapid-responses "BMJ Article Related Rapid Responses")[](https://www.bmj.com/panels_ajax_tab/bmj_related_rapid_responses/node:1129160/1 "BMJ Article Related Rapid Responses") * [Peer review](https://www.bmj.com/content/395/bmj-2026-101163/peer-review "Article Tab - Peer review")[](https://www.bmj.com/panels_ajax_tab/jnl_bmj_tab_peer_review/node:1129160/1 "Article Tab - Peer review") * [](https://www.bmj.com/content/395/bmj-2026-101163/submit-a-rapid-response "BMJ Rapid Responses Form")[](https://www.bmj.com/panels_ajax_tab/bmj_rapid_responses_form/node:1129160/1 "BMJ Rapid Responses Form") ![Loading](https://www.bmj.com/sites/all/modules/contrib/panels_ajax_tab/images/loading.gif) 1. [Gareth Iacobucci](https://www.bmj.com/about-bmj/editorial-staff/gareth-iacobucci "Gareth Iacobucci") [Author affiliations](https://www.bmj.com/content/395/bmj-2026-101163.short?rss=1) 1. The BMJ ## Don’t you step on my blue shade poos Sound advice. But examining them could actually be enlightening, scientists say. A new research project is aiming to reveal the connection between speedy digestion and quick thinking. ## Through blue poo? Yes. The experts, from the University of Southampton, have come up with a toilet test that allows people to time how quickly their bodies digest an edible muffin made with blue dye. ## Tangled up in blue? Once participants’ poo turns blue from the dye, they will be asked to play online games … [View Full Text](https://www.bmj.com/content/395/bmj-2026-101163.full) ## Log in ### Log in using your username and password [BMA Member Log In](https://bmjverification.bma.org.uk/validate/userdetails?url=https%3A//www.bmj.com/content/395/bmj-2026-101163%3Frss%3D1%26variant%3Dshort%26sso%3D "Log in here if you are a BMA member.") If you have a subscription to The BMJ, log in: Username * Password * [Forgot your log in details?](https://www.bmj.com/user/password "Retrieve your credentials.") * [Need to activate](https://journals.bmj.com/cgi/activate/basic) * [Log in via institution](https://www.bmj.com/login/shibboleth?uri=https%3A%2F%2Fwww.bmj.com%2Fcontent%2F395%2Fbmj-2026-101163%3Frss%3D1&subcode=bmjjournals&env=prod) * [Log in via OpenAthens](https://openathens-sp.highwire.org/session/init?entityID=https%3A//idp.eduserv.org.uk/openathens&subcode=bmjjournals&hw-shib-return-uri=https%253A%252F%252Fwww.bmj.com%252Fcontent%252F395%252Fbmj-2026-101163.short%253Frss%253D1) ### Log in through your institution ## Subscribe from £184 * Subscribe and get access to all BMJ articles, and much more. [Subscribe](https://www.bmj.com/us/subscribe) * For online subscription **Access this article for 1 day for: £50 / $60/ €56** ([excludes VAT](https://www.bmj.com/company/eu-vat-rates/)) You can download a PDF version for your personal record. [Buy this article](https://www.bmj.com/highwire/payment/ppv/1129160) * [Tweet Widget](http://twitter.com/share?url=https%3A//www.bmj.com/content/395/bmj-2026-101163&count=horizontal&via=&text=%E2%80%9CBlue%20poo%E2%80%9D%20could%20reveal%20links%20between%20gut%20and%20brain%20function%2C%20say%20scientists&counturl=www.bmj.com/content/395/bmj-2026-101163 "Tweet This") ## Article tools [PDF](https://www.bmj.com/content/395/bmj-2026-101163.full.pdf "PDF")[0 responses](https://www.bmj.com/content/395/bmj-2026-101163/rapid-responses) * [Respond to this article](https://www.bmj.com/content/395/bmj-2026-101163/submit-a-rapid-response) * [Print](https://www.bmj.com/content/395/bmj-2026-101163.full-text.print) * [Alerts & updates](https://www.bmj.com/#mini-panel-jnl-bmj-article-page-alerts-1) #### Article alerts Please note: your email address is provided to the journal, which may use this information for marketing purposes. #### Log in or register: Username * Password * [Register for alerts](https://myaccount.bmj.com/myaccount/registration.html?regService=bmj-registration&fwdUrl=https://www.bmj.com/content/395/bmj-2026-101163?tab=article-alert&itemId=pr1906) If you have registered for alerts, you should use your registered email address as your username * [Citation tools](https://www.bmj.com/#mini-panel-article-page-citation-download-1) #### Download this article to citation manager Gareth Iacobucci Iacobucci G. “Blue poo” could reveal links between gut and brain function, say scientists BMJ 2026; 395 :e101163 doi:10.1136/bmj-2026-101163 * BibTeX (win & mac)[Download](https://www.bmj.com/highwire/citation/1129160/bibtext) * EndNote (tagged)[Download](https://www.bmj.com/highwire/citation/1129160/endnote-tagged) * EndNote 8 (xml)[Download](https://www.bmj.com/highwire/citation/1129160/endnote-8-xml) * RefWorks Tagged (win & mac)[Download](https://www.bmj.com/highwire/citation/1129160/refworks-tagged) * RIS (win only)[Download](https://www.bmj.com/highwire/citation/1129160/ris) * Medlars[Download](https://www.bmj.com/highwire/citation/1129160/medlars) ## Help If you are unable to import citations, please contact technical support for your product directly (links go to external sites): * [EndNote](http://www.endnote.com/support/ensupport.asp) * [ProCite](http://www.procite.com/support/pcsupport.asp) * [Reference Manager](http://www.refman.com/support/rmsupport.asp) * [RefWorks](http://www.refworks.com/content/products/content.asp) * [Zotero](http://www.zotero.org/support) * [Request permissions](https://s100.copyright.com/AppDispatchServlet?publisherName=BMJ&publication=bmj&title=%E2%80%9CBlue%20poo%E2%80%9D%20could%20reveal%20links%20between%20gut%20and%20brain%20function%2C%20say%20scientists&publicationDate=10/21/2026&author=Gareth%20Iacobucci&contentID=10.1136/bmj-2026-101163&volumeNum=395&issueNum=&startPage=&endPage=&copyright=BMJ%20Publishing%20Group%20Ltd&oa=n&orderBeanReset=1&link_type=PERMISSIONDIRECT&atom=/bmj/395/bmj-2026-101163.atom) * [Author citation](https://www.bmj.com/#mini-panel-jnl-bmj-article-page-citation) * [Articles by Gareth Iacobucci](https://www.ncbi.nlm.nih.gov/sites/entrez?cmd=search&db=pubmed&term=Iacobucci%20Gareth%5Bau%5D&dispmax=50) * [Add article to BMJ Portfolio](https://portfolio.bmj.com/portfolio/add-to-portfolio.html?t=%E2%80%9CBlue%20poo%E2%80%9D%20could%20reveal%20links%20between%20gut%20and%20brain%20function%2C%20say%20scientists&u=https%3A//www.bmj.com/content/395/bmj-2026-101163) [Email to a friend](https://www.bmj.com/#mini-panel-jnl-bmj-article-button-email-to-1) #### Forward this page Thank you for your interest in spreading the word about The BMJ. NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address. Username * Your Email * Send To * You are going to email the following [“Blue poo” could reveal links between gut and brain function, say scientists](https://www.bmj.com/content/395/bmj-2026-101163) Your Personal Message CAPTCHA This question is for testing whether or not you are a human visitor and to prevent automated spam submissions. ![](https://crossmark-cdn.crossref.org/widget/v2.0/logos/CROSSMARK_Color_horizontal.svg) ## This week's poll Should medical students be encouraged to use generative artificial intelligence to study? Yes No Vote[View Results](javascript:PD_vote58250\(1\);) [Read](https://www.bmj.com/content/390/bmj.r1418) related article [See](https://www.bmj.com/about-bmj/poll-archive) previous polls [ Back to top](https://www.bmj.com/content/395/bmj-2026-101163.short?rss=1#page) ## Follow us on * [X](https://x.com/bmj_latest) * [Facebook](https://www.facebook.com/bmjdotcom) * [Instagram](https://www.instagram.com/the_bmj_) * [Linkedin](https://www.linkedin.com/showcase/the-bmj/) * [YouTube](http://youtube.com/user/BMJmedia) * [RSS](http://feeds.bmj.com/bmj/recent) ## Content links * [Collections](http://www.bmj.com/collections) * [Health in South Asia](http://www.bmj.com/health-in-south-asia) * [Women’s, children’s & adolescents’ health](http://www.bmj.com/content/women%E2%80%99s-children%E2%80%99s-and-adolescents%E2%80%99-health-0) * [Zika virus](http://www.bmj.com/freezikaresources) * [Research](https://www.bmj.com/us/research) * [Education](https://www.bmj.com/us/education) * [News and views](https://www.bmj.com/us/news) * [BMJ Opinion](http://blogs.bmj.com/bmj/) * [Rapid responses](https://www.bmj.com/rapid-responses) * [Archive](https://www.bmj.com/archive) ## About us * [About us](https://www.bmj.com/about-bmj) * [Editorial staff](https://www.bmj.com/about-bmj/editorial-staff) * [BMJ in the USA](https://www.bmj.com/about-bmj/editorial-staff/bmj-united-states) * [BMJ in Latin America](https://www.bmj.com/health-in-latin-america) * [BMJ in South Asia](https://www.bmj.com/about-bmj/editorial-staff/bmj-south-asia) * [Advisers](https://www.bmj.com/about-bmj/advisory-panels) * [Policies](https://www.bmj.com/about-bmj/resources-authors/forms-policies-and-checklists) * [Submit your paper](http://mc.manuscriptcentral.com/bmj) ## Resources * [Authors](https://www.bmj.com/about-bmj/resources-authors) * [Reviewers](https://www.bmj.com/about-bmj/resources-reviewers) * [BMA members](https://www.bmj.com/about-bmj/resources-bma-members) * [Readers](https://www.bmj.com/about-bmj/resources-readers) * [Subscribers](https://www.bmj.com/about-bmj/resources-subscribers) * [Advertisers and sponsors](https://www.bmj.com/about-bmj/resources-advertisers-and-sponsors) * [Media](https://www.bmj.com/about-bmj/resources-media) * [Recruiters](https://recruiter.bmj.com/) ## Explore BMJ * [Our company](https://www.bmj.com/company/?int_source=tbmj&int_medium=footer&int_campaign=URLswitch) * [BMJ Careers](https://jobs.bmj.com/) * [BMJ Learning](http://learning.bmj.com/) * [BMJ Masterclasses](http://masterclasses.bmj.com) * [BMJ Journals](http://journals.bmj.com) * [BMJ Student](https://www.bmj.com/student) * [Academic edition of The BMJ](http://www.bmj.com/about-bmj/resources-readers) * [BMJ Best Practice](http://bestpractice.bmj.com/) * [The BMJ Awards](http://thebmjawards.bmj.com/home) ## My account * [Email alerts](http://myaccount.bmj.com/myaccount/account/hw-registration.html) * [Activate subscription](http://journals.bmj.com/cgi/activate) ## Information * [Contact us](https://www.bmj.com/about-bmj/contact-us) * [Complaints](https://www.bmj.com/about-bmj/complaints-procedure) * [Accessibility](https://journals.bmj.com/our-journals/accessibility-tbmj/) * Cookie settings * [Cookie Policy](https://bmjgroup.com/cookie-notice-at-bmj-group/) * [Privacy policy](https://bmjgroup.com/privacy-notice/) * [Website T&Cs](https://bmjgroup.com/website-terms-and-conditions/) * [Revenue Sources](http://group.bmj.com/group/about/revenue-sources) * [HighWire Press](http://home.highwire.org/) * [Sitemap](https://www.bmj.com/sitemap) * [Legal Information](https://bmjgroup.com/legal-information/) Copyright © 2026 BMJ Publishing Group Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.
## Related Clinical Research

- [Artificial intelligence applications in liver transplantation: scoping review of 196 studies](https://medichelpline.com/clinical-feed/plos-one-15-the-applications-of-artificial-intelligence-in-liver-transplantation-a.md)
- [Stool chemistry plus metagenomics identifies distinct adult gut health profiles](https://medichelpline.com/clinical-feed/biorxiv-6-integrating-stool-chemistry-measurements-with-metagenomics-in-adults-reveals.md)
- [IBDex frozen atlas converts bulk transcriptomics into reusable IBD reference](https://medichelpline.com/clinical-feed/medrxiv-17-ibdex-a-frozen-patient-scale-atlas-for-bulk-transcriptomics-in-inflammatory.md)
- [ERG344 ACOD1 inhibition reduces colitis and tumor growth via a shared myeloid mechanism](https://medichelpline.com/clinical-feed/biorxiv-19-small-molecule-acod1-inhibition-attenuates-colitis-and-tumor-growth-through-a.md)
- [Efficient Parsing Techniques for Automated Entity Extraction in Software Requirements](https://medichelpline.com/clinical-feed/plos-one-7-parsing-based-approach-for-entity-extraction-from-natural-language-software.md)

## Navigation
- [← Back to Gastroenterology Feed](https://medichelpline.com/clinical-feed/gastroenterology.md)
- [← All Clinical Specialties](https://medichelpline.com/clinical-feed.md)
## Medical & Regulatory Disclaimer

> [!CAUTION]
> MedicHelpline content is structured for research, educational, and professional discovery purposes. It does not constitute individual medical advice, clinical diagnosis, or treatment recommendations.
> Always verify dosing, contraindications, and regulatory alerts against official product labeling and primary regulatory sources before clinical decision-making.