Side by side

1. 1.Carries electrons in the reactions that turn food into ATP.
2. 2.Supplies the substrate that sirtuins and PARP enzymes need; both are involved in DNA repair and cellular stress response.
3. 3.NAD+ falls with age and in metabolic disease, which is the rationale for supplementing it.
4. 4.Infused NAD+ reaches blood cells but is poorly taken up by other tissues; oral precursors raise whole-body NAD+ more reliably.
5. 5.Raised NAD+ in humans has not been shown to produce clinical benefits in controlled trials.

• Ageing and 'cellular energy' claims
• Metabolic and muscle function (oral precursors)
• Alcohol and substance withdrawal protocols
• Parkinson's disease (early trials)
• Chronic fatigue and cognitive complaints

• Measured NAD+ levels rise with precursors
• Small improvements in some metabolic markers in early trials
• No demonstrated effect on lifespan, frailty or cognition in people
• Temporary flushing and nausea with rapid infusion

• Flushing, warmth, chest tightness or breathlessness if infused quickly
• Nausea, headache, dizziness
• Fatigue after infusion
• Infection and vein inflammation from repeated intravenous access
• Oral precursors: mild nausea and itching at higher doses

Research context only — no approved regimen exists. Clinics give infusions of roughly 250–1000 mg over one to several hours, often weekly; the slower the infusion, the milder the side effects. Vendors sell escalating weekly schedules such as 25 mg rising to 150 mg, with syringe units that are meaningless without the vial concentration. Oral precursor trials used 250–1000 mg daily. None of these are validated against a clinical outcome.

Research context only