What is NAD+?
Nicotinamide adenine dinucleotide (NAD+) is a coenzyme present in every living cell, essential for hundreds of metabolic reactions. It plays a central role in three critical areas: energy production (as an electron carrier in mitochondrial respiration), DNA repair (as a substrate for PARP enzymes), and cellular signalling (as a cofactor for sirtuin proteins, which regulate gene expression, inflammation, and stress responses).
Why NAD+ declines with age
NAD+ levels decrease steadily with age — by some estimates, declining by as much as 50% between the ages of 40 and 60. This decline is driven by increased consumption (DNA damage activates PARP enzymes, which consume NAD+), decreased synthesis, and increased expression of CD38, an enzyme that degrades NAD+. The result is reduced mitochondrial function, impaired DNA repair, and dysregulated gene expression — hallmarks of the ageing process.
The supplement boom
This age-related decline has fuelled enormous interest in NAD+ precursor supplements — primarily nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN). The global NAD+ supplement market has grown rapidly, with products ranging from oral capsules to intravenous infusions priced at over $1,000 per session.
However, a critical gap exists: most people taking these supplements have no baseline measurement and no way to verify whether supplementation is actually raising their NAD+ levels. This is where testing becomes essential.
What does the NAD+ Index measure?
Masdiag's NAD+ Index quantifies whole-blood NAD+ from a dried blood spot using LC-MS/MS. The test provides an objective measure of circulating NAD+ status, enabling practitioners and individuals to establish a baseline before supplementation, monitor whether a chosen intervention is effective, and track longitudinal changes over time.
Clinical context
It's important to approach NAD+ testing with nuance. While the association between NAD+ decline and ageing is well-established in research, translating this into individual clinical recommendations remains an evolving field. Blood levels of NAD+ don't necessarily reflect tissue-specific levels, and the clinical significance of a given NAD+ level varies by individual. The value of testing lies in tracking trends over time rather than interpreting a single result in isolation.
Frequently asked questions
What is a normal NAD level?
NAD+ levels vary widely between individuals and depend on age, tissue type, health status, and metabolic state. In younger adults, baseline NAD+ typically ranges from 50–100 µmol/L in whole blood. By age 60, levels often decline to 30–50 µmol/L. Rather than relying on a single "normal" reference range, the value of testing lies in establishing your personal baseline and tracking changes in response to lifestyle or supplementation interventions.
Does NMN actually raise NAD?
Some human studies show that nicotinamide mononucleotide (NMN) supplementation increases blood and tissue NAD+ levels, though the magnitude of effect varies considerably. Benefits are most apparent in older adults or those with metabolic dysfunction. However, circulating NAD+ levels don't always reflect tissue-specific changes, and translating NAD+ increases into measurable clinical health improvements remains an active research question.
Can you test NAD at home?
Traditional NAD+ testing requires venous blood collection due to the molecule's instability. However, dried blood spot methods now enable at-home fingerprick sampling, which can be posted to an accredited laboratory. This makes baseline testing and follow-up monitoring practical for individuals interested in tracking NAD+ status without repeated clinic visits.
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