NAD+ is a coenzyme that every living cell needs, cancer cells included. People taking NAD+ for longevity sometimes ask whether feeding that pathway could also feed a tumor.
The short answer is that nobody knows. The concern comes from cell and animal biology, and the human evidence is thin in both directions. This page goes through what each kind of study found. What NAD+ injections are used for, and the evidence behind them, is in NAD injections.
Why the question comes up
Tumor cells turn over NAD+ quickly, and they rely heavily on one recycling enzyme, NAMPT, to rebuild it [1]. That enzyme is overproduced in several cancers, including colorectal, breast, ovarian and prostate cancers.
That dependence made NAMPT a drug target. Blocking it drains NAD+ from tumor cells until they run out of energy, and several such drugs have reached clinical trials [1].
The worry about supplements runs the same logic in reverse. If starving a tumor of NAD+ can kill it, could adding NAD+ help it? That is a reasonable hypothesis. It is not a finding in people.
What animal studies found
The animal results do not agree with each other. Each used a different cancer, and not all used the same precursor.
| Study | Cancer model | Precursor | Finding |
|---|---|---|---|
| Maric 2023 | Triple-negative breast cancer | Nicotinamide riboside (NR) | More cancer and more spread to the brain |
| Pang 2023 | Liver cancer | NR, 400 mg/kg daily | Less spread, smaller tumors, longer survival |
| Nakazzi 2026 | Pancreatic cancer | Nicotinamide, NMN | Resistance to chemotherapy; supported tumor growth |
In the breast cancer study, NR raised both how often cancer took hold and how often it spread to the brain [4]. The authors concluded that NR’s use may need to be personalized in some patient groups.
The liver cancer study found the opposite. NR reduced spread to the lungs, bone and liver in mice, shrank tumors, and extended survival [5]. Its authors proposed NR as a possible treatment.
The pancreatic cancer study tested cells and mice given chemotherapy [6]. NMN protected cancer cells most strongly against three chemotherapy drugs. In mice, nicotinamide and NMN made chemotherapy work less well and supported cancer growth.
Mouse doses and mouse tumors do not predict what happens in people. What these studies show is that the effect may depend on the cancer, and on whether a cancer is already present.
What human trials found
The only randomized human trials with cancer as the outcome used nicotinamide, a form of vitamin B3 that the body converts into NAD+. They tested it as a way to prevent skin cancer.
ONTRAC enrolled 386 adults who had had at least two non-melanoma skin cancers in the past 5 years [2]. On nicotinamide 500 mg twice daily for 12 months, new skin cancers were 23% lower than on placebo (95% CI, 4 to 38). The benefit did not last after people stopped.
A second trial tried the same dose in 158 organ-transplant recipients, whose immune systems are suppressed [3]. It found no difference: 207 new skin cancers on nicotinamide and 210 on placebo (rate ratio 1.0; 95% CI, 0.8 to 1.3).
Those trials measured skin cancer only, for one year, in people at high risk of it. They say nothing about other cancers, about NR or NMN, or about injected NAD+. How nicotinamide relates to the skin more broadly is covered in NAD+ benefits for skin.
What has not been studied
A 2026 systematic review found 33 human intervention studies of NAD-related compounds [8]. Oral NR and NMN raised NAD+ markers and were generally well tolerated over weeks to months. Studies that short cannot show whether cancer risk changes over years.
The same review found no outcome trials of intravenous or intramuscular NAD+ for anti-aging or wellness use. A 2023 review in Endocrine Reviews likewise described the clinical pharmacology of NAD+ precursors as incompletely understood, and called for adequately powered randomized trials [7].
How NAD+ is supplied
NAD+ injections and drips are made by compounding pharmacies, not sold as an FDA-approved drug. The FDA lists NAD in 503A Category 1, the bulk substances still under evaluation for compounding [9].
What this means
There is no human evidence that NAD+ or its precursors cause cancer. There is also no human evidence that they are safe on that score over years, because no trial has run that long. The animal data point both ways.
Short-term reactions to NAD+ are covered in NAD side effects. The differences between precursors are in NMN vs NAD.