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WellnessChecked Editorial · July 2026
NAD+ Supplement Guide — What It Is and How to Raise It
Complete guide to NAD+ — why it declines with age, what happens when it does, and how NMN and NR supplementation restores it. Published human evidence reviewed.
⚡ Quick AnswerLast Reviewed: July 2026
NAD+ (Nicotinamide Adenine Dinucleotide) is a coenzyme essential for cellular energy, DNA repair and sirtuin activation. It declines approximately 50% between ages 40 and 60. The most evidence-backed ways to raise NAD+ are NMN supplementation (250-500mg daily) and NR supplementation.
What Is NAD+?
NAD+ (Nicotinamide Adenine Dinucleotide) is a coenzyme present in every living cell. It participates in hundreds of metabolic reactions as an electron carrier — accepting and donating electrons in the processes that generate ATP (cellular energy). It also serves as a co-substrate for sirtuin proteins and PARP DNA repair enzymes.
Why NAD+ Declines With Age
NAD+ biosynthesis declines with age due to three converging factors: reduced expression of NAMPT (the rate-limiting enzyme in the salvage pathway), increased consumption by CD38 (an enzyme that rises with age and inflammation) and increased PARP activity from accumulated DNA damage. The net result is approximately 50% decline in cellular NAD+ between ages 40 and 60.
The Three Functions of NAD+
Energy metabolism: NAD+ is essential to Complex I of the mitochondrial electron transport chain — the machinery that produces ATP
DNA repair: PARP1 and PARP2 enzymes consume NAD+ to fuel DNA strand break repair
Sirtuin activation: SIRT1-7 longevity proteins use NAD+ as a co-substrate for deacylase activity
How to Raise NAD+ with Supplements
NMN (250-500mg) — direct NAD+ precursor via the salvage pathway. Washington University human trial confirmed blood NAD+ elevation
NR (300-1000mg) — indirect precursor that converts to NMN then NAD+. ChromaDex Tru Niagen human trials
Trans-Resveratrol — not a precursor but activates sirtuins, making more efficient use of available NAD+
NAD+ (Nicotinamide Adenine Dinucleotide) is a coenzyme present in every cell, essential for energy metabolism, DNA repair and longevity protein (sirtuin) activation.
Three factors: reduced NAMPT enzyme expression, increased CD38 enzyme activity, and greater PARP DNA repair consumption. Net result is ~50% decline between ages 40-60.
NMN at 250-500mg daily is the most direct approach with published human clinical evidence. NR also elevates NAD+ via an indirect pathway.
A 2023 Japanese study found NMN superior to NR at equivalent doses for NAD+ elevation in older adults.
Exercise stimulates NAMPT expression. Fasting activates AMPK which supports NAD+ biosynthesis. But supplementation is the most reliable approach for meaningful NAD+ restoration.
Disclaimer: For informational purposes only. Dietary supplements — not medicines. Not intended to diagnose, treat, cure or prevent any disease. FDA/MHRA not evaluated. Individual results vary. Consult healthcare professional. Affiliate commissions may be earned. Full disclaimer →