The human study discussed here does not establish that NAD⁺ supplements treat kidney disease. It tested a combination of nicotinamide riboside and pterostilbene in 24 hospitalized people with acute kidney injury. Blood NAD⁺ increased, and the short treatment period produced no major safety signal. The trial was not designed to establish recovery of kidney function or long-term safety. [1]
Acute kidney injury is a recent decline in kidney function. Chronic kidney disease is a different clinical setting, often involving persistent abnormalities and different medication considerations. Evidence from one cannot be carried across automatically. Our NAD safety overview explains why a safety statement must identify the population and formulation it actually covers.
What was tested
The intervention combined oral NR with pterostilbene, abbreviated NRPT. It was not NAD⁺ infused into a vein, NR alone, NMN alone or a general multivitamin. A combination study cannot tell us which ingredient caused a change or whether either ingredient alone would produce the same result. [1]
| Study and participants | Design and outcome | Finding | Main limit |
|---|---|---|---|
| Simic et al.; n = 24 hospitalized AKI patients [1] | Randomized, blinded, four-step dose-escalation study; NR plus pterostilbene versus placebo | Pooled treated group: blood NAD⁺ +37% at 48 hours vs baseline; p = 0.002. | 20 treated, four placebo; two placebo participants left before completion. |
| Safety observations [1] | Two-day treatment; symptoms and laboratory monitoring | Three treated participants reported minor gastrointestinal symptoms. | Brief exposure; mostly mild AKI; cannot establish long-term or broad kidney-disease safety. |
The investigators used four escalating-dose steps. Each step assigned five participants to NRPT and one to placebo, resulting in 20 treated participants and only four placebo recipients overall. Treatment lasted two days. Describing this as a randomized trial is accurate, but leaving out its small control group would make it sound more definitive than it was.
The blood finding was real but limited
When all active-treatment steps were pooled, whole-blood NAD⁺ increased by 37% at 48 hours compared with baseline (p = 0.002). Individual responses varied considerably. Only one dose step had a statistically significant increase on its own. [1]
That pooled within-group change is not a 37% improvement in kidney function. It is a change in a blood metabolite. Whole-blood NAD⁺ also does not directly measure NAD⁺ inside kidney tissue. The study authors explicitly identified that measurement limitation.
It is tempting to read any rise as evidence that a deficiency has been corrected. A trial needs a validated link between the measurement and the desired clinical outcome before that conclusion follows. The NR explainer covers the precursor mechanism; our evidence guide covers the difference between changing a pathway and improving health.
What “well tolerated” means here
Three of the 20 NRPT recipients reported minor gastrointestinal symptoms. The reported safety laboratory tests, including creatinine, estimated filtration rate, electrolytes, liver tests and blood counts, did not show a concerning treatment-related change over the brief observation period. [1]
Those findings support further study under monitoring. They do not certify safety for months of use, for severe kidney failure, for dialysis patients or for every combination of medications. A small study can miss uncommon adverse events, and two days cannot reveal delayed effects. The absence of a short-term laboratory problem is also not evidence that injured kidneys recovered faster.
Who was left out of the answer?
The study enrolled people able to give written consent after acute kidney injury had developed. The authors noted that this resulted in a group with relatively mild injury from a range of non-life-threatening causes. More severe settings, such as major surgery or sepsis, may behave differently. Treatment began after the injury had already been recognized and the enrollment process completed. [1]
Two of the four placebo participants were discharged before completing the study. With so few controls, losing two patients substantially weakens comparisons. The pilot is therefore best read as an early feasibility and safety step, not as a small version of a definitive treatment trial.
What a useful follow-up would measure
A treatment trial would need enough participants and follow-up to assess meaningful recovery: the course of kidney function, need for additional support and other prespecified clinical outcomes. It would need to distinguish the combination from its individual ingredients and explain which kidney population is being studied. Those requirements are more demanding than showing a blood NAD⁺ increase.
For someone already receiving kidney care, this paper is a discussion point rather than a supplement instruction. A clinician can assess the relevance of the formulation, other medications and current kidney function. If research participation is of interest, our registry guide shows how to check eligibility and contact an actual study team without treating a marketing page as an enrollment offer.