Is Irisin legal in the United Kingdom?

A muscle-derived protein fragment that browns white fat in mice. No study has given irisin to a human, and whether commercial blood tests for it measure irisin at all was challenged in 2015 and answered only by mass spectrometry.

Irisin was described in 2012 as a hormone cut from the muscle membrane protein FNDC5 in response to exercise, which then acts on white fat to make it burn energy like brown fat. That paper was in mice, with some human cell work.

Mechanism: In mice: exercise raises the transcriptional coactivator PGC-1alpha in muscle, which induces FNDC5; the extracellular part of FNDC5 is cleaved and released as irisin, which acts on white adipocytes to induce UCP1 and a brown-fat-like thermogenic programme, raising energy expenditure and improving glucose handling. A 2018 Cell paper identified alpha-V integrins as irisin receptors in mouse bone and fat.

Regulatory history: Not FDA-approved. No irisin product is approved or in registered clinical development anywhere, and no trial has administered irisin to a human.

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 Irisin 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.