NAD+ Human Research: What the Oral NR Trials Actually Found

Martens 2018: a small crossover trial in healthy older adults

The Nature Communications study enrolled 24 healthy middle-aged and older adults aged 55–79. Its randomized, double-blind, placebo-controlled crossover design compared six-week treatment periods within the same participants.

NR increased NAD+ metabolism and was reported as well tolerated over the study period. The investigators also explored physiological outcomes including blood pressure and arterial stiffness. They described these findings as initial evidence requiring further study, not established cardiovascular prevention.

A crossover design can reduce between-person variation. It does not remove the limitations of a small sample, short exposure or exploratory analyses. The trial did not demonstrate longer human lifespan or reversal of biological aging.

Dollerup 2018: the insulin-sensitivity result was negative

The American Journal of Clinical Nutrition study randomized 40 sedentary men with obesity, aged 40–70, in a double-blind, placebo-controlled parallel-group trial lasting 12 weeks.

NR did not improve insulin sensitivity or the measured glucose-metabolism outcomes. The population and endpoints differed from the Martens trial. A null finding in this setting is meaningful evidence against assuming metabolic benefits from an increase in NAD-related markers alone.

The study does not settle every question about NR in every disease or age group. Equally, positive results elsewhere cannot erase this negative finding or turn it into proof that NR treats insulin resistance.

Biochemical activity is not the same as clinical benefit

A biomarker can show that an intervention affected a pathway. A clinical endpoint asks whether people experienced a meaningful change, such as improved function or fewer disease events. The two should be reported separately.

Blood measurements may not reflect NAD+ concentrations in a specific tissue or cellular compartment. A short-term increase also does not establish a lasting effect. Claims about energy, cognition, weight, longevity or disease prevention need trials designed to measure those outcomes.

Exploratory findings can generate hypotheses, but repeated testing of many outcomes raises the chance of apparently positive results. Stronger conclusions require prespecified endpoints, adequate sample sizes and independent replication.

How to read tolerability statements

“Well tolerated” applies to the participants, formulation and exposure studied. These short oral NR trials cannot rule out uncommon adverse effects, establish long-term safety or validate injectable NAD+ products.

Neither trial tested the composition, sterility or suitability of FirstLabs stock. A laboratory certificate is analytical documentation and cannot replace a human safety study or drug authorization.

Human NAD+ research: frequently asked questions

Did the 2018 NR trials prove that NAD+ reverses aging?

No. Neither trial established human lifespan extension or aging reversal.

Did NR improve insulin sensitivity in the trial in men with obesity?

No. The 12-week, 40-participant Dollerup trial found no improvement in insulin sensitivity.

Are these results evidence for direct NAD+ injections?

No. Both studies used oral NR, a different molecule and route from direct NAD+ administration.