NAD+ : données probantes, mécanisme et limites

NAD+ is an essential coenzyme. Cells use it to carry electrons in energy metabolism and as a substrate for enzymes such as sirtuins, PARP enzymes and CD38. NAD+ levels decline with age in many tissues.

NAD+ is not a peptide. It appears in peptide discussions because clinics and sellers often offer it alongside peptides. Two approaches are marketed: giving NAD+ directly, often by infusion, and taking oral precursors such as nicotinamide riboside (NR) or nicotinamide mononucleotide (NMN), which the body converts into NAD+.

The idea is that restoring NAD+ supports the enzymes that depend on it and so slows parts of aging. Strong support for that idea comes from animal studies. In humans, the measured effect is a rise in NAD and related molecules in blood, which is a biomarker, not a health outcome.

A human pharmacokinetic study found that oral NR raised the blood NAD+ metabolome, with larger rises after larger single amounts. Several of its authors held stock in or worked for ChromaDex, the NR supplier and study sponsor.

A randomized, double-blind, placebo-controlled crossover trial in healthy middle-aged and older adults found that NR was well tolerated and stimulated NAD+ metabolism over six weeks per phase. The authors suggested that future trials test blood pressure and arterial stiffness. The trial did not establish those benefits.

A 2023 review assessed 25 published human NR studies. It concluded that oral NR has shown few clinically relevant effects and that the literature tends to exaggerate the importance and robustness of reported effects. It noted possible roles in inflammation and some severe diseases that need more study.

Results for energy, cognition and healthspan markers are mixed. The reviewed sources do not test infused NAD+, so claims for NAD+ infusions or shots rest on indirect evidence.

In the reviewed randomized trial, oral NR was well tolerated over the short study period. That finding applies to the precursor tested, not to NAD+ given by infusion or injection.

The safety of infused or injected NAD+ has not been characterized in controlled trials among the sources reviewed, and long-term safety of any NAD-raising approach is not established. Products sold outside approved drug channels are not reviewed by a regulator for identity, purity or sterility.

NAD+ is not approved by the FDA as a drug, and no product with NAD+ as an active ingredient appears in Health Canada's Drug Product Database.

NAD+ itself is not named on the WADA Prohibited List. WADA's method rules prohibit intravenous infusions or injections above a set total volume in a 12-hour period, whatever the substance, unless received in hospital treatment, surgery or clinical investigations. Athletes should check with their anti-doping agency before any infusion.