Is Berberine legal in the United Kingdom?

46 randomised trials show HbA1c down 0.73 percentage points, and a head to head against metformin found comparable glucose lowering. No outcome trial, mostly small single-region trials, and a third of patients get gastrointestinal side effects.

Berberine has the largest randomised literature of anything sold as a metabolic supplement, and the nickname it earned online is not baseless: a 2008 trial randomised 36 newly diagnosed patients to berberine or metformin and found the glucose lowering similar. 86 mmol/L, and improved insulin resistance and lipids as well.

Mechanism: An isoquinoline alkaloid that activates AMP-activated protein kinase, which is the same node metformin acts through, largely via mild inhibition of mitochondrial complex I raising the AMP to ATP ratio. Downstream that increases glucose uptake, suppresses hepatic gluconeogenesis and reduces lipogenesis.

Regulatory history: Sold as a dietary supplement in the United States. Not approved for diabetes or any other indication. Used as a prescription antidiarrhoeal in some other countries.

Licenses medicines for the UK market. A compound without a marketing authorisation is an unlicensed medicine, which can only lawfully be supplied for human use through a prescriber under the specials scheme, not sold as a research product.

The classification above is the The Longevity Archive reading of Medicines and Healthcare products Regulatory Agency listings for Berberine at the reviewed date, not a legal opinion. Rules change, and importing, prescribing and possessing a compound can each be treated differently. Check the regulator directly before acting on anything here.