NAD is a coenzyme involved in cellular metabolism. NMN and nicotinamide riboside, or NR, are related to pathways that produce NAD, but they are not identical substances. A study of one should not be cited as proof that another formulation produces the same result.

A randomized NR study in middle-aged and older adults reported changes in NAD metabolism. A separate NMN trial in women with prediabetes examined muscle insulin sensitivity. These studies provide human evidence for specific biochemical or metabolic outcomes in defined populations. Neither is a trial demonstrating longer human life. NR crossover trial in healthy middle aged and older adults NMN trial in women with prediabetes

Biomarkers and benefits are different endpoints

An increase in a blood measurement can show that an intervention affects a pathway. It does not automatically establish better cognition, endurance, disease prevention or longevity. A clinical benefit needs to be measured directly or supported by a validated relationship appropriate to the claim.

Tissue also matters. A change in circulating NAD-related measures does not establish the same change in every organ. The analytical method and sample timing should be examined before comparing percentages across studies.

Do not treat absence of superiority as equivalence

Separate small trials cannot reliably determine whether NAD, NMN or NR is best. Participants, formulations, follow-up and outcome selection differ. A direct comparative study would need a defined purpose and enough participants to detect meaningful differences.

For AXON, the useful comparison is an evidence map: substance, formulation, population, measured outcome and unresolved question. Product approval, supplement status and advertising claims require their own current regulatory checks. This article does not recommend supplementation, infusion or nasal use, and it provides no dosing guidance. The defensible conclusion is narrower than anti-aging marketing: selected interventions have been studied in humans, while broad health and longevity promises remain unproven by those studies.