Is NRH legal in the United Kingdom?

Raises cellular NAD by 2.5 to 10-fold within an hour in cultured mammalian cells, more than NR or NMN at equivalent concentrations, and reaches tissues in mice. It has never been given to a human being in a published trial, and it is already sold to consumers.

NRH is the reduced form of nicotinamide riboside, and it is the most potent NAD-raising molecule in this batch by a wide margin. Every number supporting that statement comes from cultured cells or from mice.

Mechanism: NRH is converted to NMNH by an ATP-dependent kinase activity found in cell lysates that is independent of NRK1 and NRK2, and NMNH is then adenylylated by NMNAT enzymes to NADH, which enters the NAD pool. Bypassing the NRK step is the proposed reason NRH outperforms NR, since NRK1 expression is rate-limiting for NR utilisation and is not required here.

Regulatory history: Not an approved drug and not an established dietary ingredient in the United States. It is sold by research-chemical and supplement vendors without any published human safety data. FDA has not evaluated it.

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 NRH 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.