Introduction
NAD+ declines with age. Restoring cellular NAD+ via precursors like NMN or NR is the most-studied direct longevity intervention available to consumers today.
How We Evaluate Products
We score each product across six pillars: ingredient quality, transparency, manufacturing, third-party testing, value, and scientific support. The overall score is the weighted mean of these pillars on a 0–100 scale.
Top Picks
- Longevity Box NMN: best overall NMN (92/100), with verified ≥99% purity and public COAs
- NAD Direct Enhanced Optima Max: best clinic-grade NAD+ (89/100), CQC-regulated with 500+ global clinics
- CZTL Methylene Blue: best methylene blue (92/100), USP pharmaceutical-grade verified
| Brand | Active | Dose | Purity / Credential | Price / Month | Score |
|---|---|---|---|---|---|
| Longevity Box | NMN | 500 mg | ≥99% (COA verified) | ~£40 | 92 / 100 |
| NAD Direct | NAD+ (direct) | 250 mg | GMP · CQC regulated | £75 | 89 / 100 |
| CZTL | Methylene Blue | Varies | USP pharmaceutical-grade | ~£30 | 92 / 100 |
NMN vs Direct NAD+ vs NR: Which Should You Choose?
NMN (Longevity Box): Most direct NAD+ precursor with the strongest recent human trial data. Converts to NAD+ via one enzymatic step. Best price-to-purity ratio in our review set.
Direct NAD+ (NAD Direct): Skips the precursor conversion pathway. Backed by a clinical group administering 100,000+ infusions annually. Premium price is justified if you want the closest analogue to a clinic protocol. Their Smart Pen injectable takes this a step further.
Methylene Blue (CZTL): Not a NAD+ precursor. It supports mitochondrial electron transport as an alternative carrier and works best alongside an NAD+ supplement rather than as a replacement for one.
FAQ
Is NMN safe? Human trials to date have shown a favorable safety profile at typical doses of 250–500 mg/day.
NMN or direct NAD+? Both raise intracellular NAD+. NMN requires one enzymatic conversion; direct NAD+ bypasses that step. Clinical data on oral direct NAD+ bioavailability is still emerging but supported by IV infusion evidence from clinical groups like NAD Direct.
What dose should I use? Most human trials on NMN use 250–500 mg daily. NAD Direct's oral supplement delivers 250 mg direct NAD+.
Can I take NAD+ and methylene blue together? Both support mitochondrial function via different mechanisms and are commonly combined. Consult a physician if you are on any medications before combining supplements.
Our #1 Pick for NMN
Longevity Box earns the top NMN score on purity, transparency, and value. We may earn a commission on qualifying purchases.