Regulators seldom publish a sentence about what they are not regulating. One appeared on 18 August, tucked inside a paper for drug developers, and it is why this item belongs on a supplements desk rather than a pharmaceutical one.
The Medicines and Healthcare products Regulatory Agency has published a position paper on microbiome-based medicinal products — MBMPs, in the agency’s shorthand. It confirms that products whose principal therapeutic effect is mediated through modulating the human microbiome fall inside the existing UK medicines framework, and says they may be regulated as biological medicinal products, or in some cases as advanced therapy medicinal products. In the accompanying announcement, Julian Beach, the agency’s executive director of healthcare quality and access, said the paper “gives developers the clarity they need to bring these innovations forward with confidence”.
The sentence that matters here
The paper draws its own edges. Foods, food supplements, cosmetics and non-therapeutic probiotics are placed outside its scope.
That is not a throwaway aside. The gut-health aisle is among the most medically worded stretches of a British supplement shelf, and a shopper could be forgiven for reading a paper on microbiome medicines as covering the capsules sold in the same vocabulary. It does not. Nothing here gives a food supplement new standing.
Presentation is the switch
The paper’s account of composition is broad — live micro-organisms, a defined consortium, a complex microbial ecosystem, or non-viable organisms and their derived components. Live biotherapeutic products, medicinal products containing live bacteria or yeasts, may qualify. Faecal microbiota transplantation, the paper notes, reaches UK patients through clinical trials, manufacturer’s specials licences or extemporaneous preparation in a pharmacy. The paper is plain about how early this is: as of July 2026, it says, no MBMP has been granted a UK marketing authorisation.
What separates all of that from the shelf is not solely the contents of the capsule, but how a product is presented and what it is intended to do. Two products containing related organisms can land in different regimes because one is offered as a food and the other as a treatment for disease. We have set out before how readily those regimes blur in marketing copy; this is the same blur, seen from the medicines side.
What has not changed
What a food supplement may say remains a matter for the Great Britain nutrition and health claims register, maintained by the Department of Health and Social Care and last updated on 19 May 2026. Whatever a pack implies, the product inside it is regulated as food in Great Britain and not as a medicine, and it is not there to diagnose, treat, cure or prevent anything.
The practical reading is unglamorous. A capsule that borrows the language of therapy has not quietly joined the medicines regime; it has taken a risk with the one it is already in. And anyone weighing a gut-health purchase against a diagnosed condition wants a GP or a pharmacist, not a label.