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Written and medically reviewed by Shiwei Han, MD, PhD Surgeon-scientist and founder of HairtheticsPublished: September 2026 · Last reviewed: September 2026
Evidence for NAD+ is not evidence for every NAD+ product.
NAD+ has become one of the most discussed molecules in longevity medicine. Consumers can now choose among oral NAD+, nicotinamide riboside (NR), nicotinamide mononucleotide (NMN), injections and intravenous infusions.
These products are often discussed as though research about NAD+ biology supports all of them equally. It does not. A scientific study may evaluate a biological mechanism, an ingredient or one specific finished formulation. Its findings cannot automatically be applied to every product bearing “NAD+” on the label.
No. NAD+, NR and NMN use different biological and delivery approaches, and individual products may differ in formulation, stability, dosing and supporting research. Evidence from one ingredient or finished formulation should not automatically be applied to another product.
Nicotinamide adenine dinucleotide, or NAD+, is a molecule found in every cell. It participates in hundreds of biochemical reactions and plays important roles in cellular energy production, metabolic regulation, DNA repair, cellular stress responses and signaling through NAD+-dependent enzymes.
NAD+ levels and metabolism can change with age, illness, inflammation and other biological factors. These observations have led researchers to investigate whether NAD+ can be replenished and what effects that replenishment may produce.
But there is an important difference between showing that NAD+ matters biologically and showing that a particular product effectively changes NAD+ inside human cells.
Products marketed for NAD+ support generally use one of several approaches:
NR (nicotinamide riboside) A precursor the body can use to produce NAD+. Evidence to examine: Research on the specific NR ingredient, dose and finished product.
NMN (nicotinamide mononucleotide) A different precursor the body can use to produce NAD+. Evidence to examine: Research on the specific NMN ingredient, dose and finished product.
Intact oral NAD+ NAD+ itself delivered in an oral formulation. Evidence to examine: Stability, delivery and human evidence for the specific finished formulation.
IV NAD+ NAD+ administered intravenously. Evidence to examine: Research on the IV route, dose, safety and measured outcomes.
These are different scientific approaches. This distinction does not establish that one entire category is superior to another.
When evaluating an NAD+ product, ask three separate questions:
Many discussions stop after the first or second question. The third question is more demanding.
A finished product includes more than the ingredient named on its label. Its formulation, manufacturing process, excipients, stability, dose and method of administration may influence its behavior. A study involving one finished formulation should not be used to promise an identical response from every other NAD+, NR or NMN product.
“Patients often ask me which NAD+ product they should choose because there are so many out there. My answer begins with a different question: What evidence exists for the exact formulation being offered?
Evidence showing that NAD+ is important to human biology does not prove that every NAD+ product is stable, effectively delivered or capable of producing a measurable intracellular response. Likewise, a study of NR, NMN or one oral NAD+ formulation cannot automatically validate a different product.
I waited to incorporate oral NAD+ into a Hairthetics clinical program until a randomized, placebo-controlled human trial evaluated the specific finished formulation we use. The reported increase in whole-blood intracellular NAD+ gave us evidence of a measurable biological response—not merely a theoretical mechanism.
That does not mean the research proves longer life or guarantees that every patient will feel differently. It means we now have formulation-specific human evidence that can support a careful physician-guided approach, with objective testing when appropriate.”
— Shiwei Han, MD, PhD
A 2026 study published in GeroScience evaluated a particular physicochemically modified, intact oral NAD+ formulation known as LathMized® NAD+.
The RENEWAL-NAD+ study was a randomized, double-blind, placebo-controlled Phase 0/1b trial involving healthy adults ages 45–75. Sixty participants were randomized, with 50 included in the primary analysis.
Participants received the studied oral formulation or placebo for five days. Researchers measured intracellular NAD+ in whole blood, circulating NAD+ in plasma, downstream NAD+ metabolites, short-term tolerability and exploratory outcomes.
The study reported that whole-blood intracellular NAD+ was 53% higher in the treatment group than in the placebo group at Day 6. Plasma NAD+ did not significantly increase.
Researchers also detected increases in two NAD+ metabolites—MeNAM and 2PY—which they interpreted as pharmacodynamic evidence consistent with downstream NAD+ metabolic flux.
Treatment was reported as generally well tolerated during the short study period. One mild nausea event occurred in the treatment group, and symptom incidence was comparable between groups.
Read the full peer-reviewed study in GeroScienceDOI: 10.1007/s11357-026-02399-1
The study measured intracellular NAD+ in whole blood. According to the authors, this measurement predominantly reflects NAD+ within red blood cells. It was not a direct measurement of NAD+ inside the brain, muscle, liver or other tissues.
The result therefore provides evidence that this oral formulation changed a measured intracellular NAD+ biomarker in blood. It should not be presented as proof that NAD+ increased by 53% in every tissue.
A compelling biomarker result can be scientifically meaningful without establishing every clinical outcome a patient might hope to achieve.
The ability to produce a measurable increase in intracellular NAD+ is an important biological finding—and a key reason formulation-specific evidence matters.
NAD+ supports cellular energy metabolism and serves as a required substrate for enzymes involved in DNA repair, cellular stress responses and metabolic regulation. A large body of basic and preclinical research provides the scientific rationale for maintaining NAD+ availability. But consumers still need evidence that the product they purchase can produce the intended biological response.
This is where the finished formulation used by Hairthetics stands apart. In a randomized, double-blind, placebo-controlled human trial, the specific intact oral NAD+ formulation used in the Precision Longevity™ program produced a 53% higher whole-blood intracellular NAD+ level than placebo at Day 6. Researchers also observed increases in the downstream metabolites MeNAM and 2PY, providing evidence consistent with active NAD+ utilization rather than simply the presence of an ingredient on a label.
Read the finished-formulation human trial in GeroScienceDOI: 10.1007/s11357-026-02399-1
What the study establishes about this formulation:
This gives patients and physicians a more direct evidentiary basis for choosing this formulation than products supported only by research on NAD+ biology, a precursor ingredient or a different delivery system.
The trial was designed to demonstrate biological delivery, pharmacodynamic activity and short-term tolerability. It was not a long-term anti-aging outcomes trial. Longer studies are still needed to determine how the measured intracellular response translates into sustained effects on energy, cognition, metabolic health, healthspan or other clinical outcomes.
That distinction should not minimize what the study demonstrated. It defines the strength of the present evidence accurately: this specific oral formulation produced a measurable intracellular NAD+ response in a placebo-controlled human trial. That is the evidence on which the Hairthetics program is built.
A recognizable ingredient and an impressive scientific reference are not enough. The reference must genuinely support the formulation and claim being presented.
Hairthetics Precision Longevity™ uses the specific intact oral NAD+ formulation evaluated in the randomized human trial described above.
The program combines the formulation with physician evaluation, a directed repletion and maintenance strategy, and specialized NAD+ biomarker testing when clinically appropriate. The purpose is not to assume that every patient will respond identically. It is to make a careful recommendation and evaluate the individual response using objective information when appropriate.
The formulation is one component of the program—not a substitute for medical evaluation or a promise of a particular clinical outcome.
NAD+ is biologically important, but that fact alone does not validate every product marketed for NAD+ support.
The best evidence is specific: specific formulation, specific dose, specific route, specific population and specific measured outcome. When one formulation produces a result in a human trial, the result belongs to that formulation and those study conditions. It should not be generalized to every NAD+, NR or NMN product.
The right question is not simply, “Is there research on NAD+?” It is: “What does the evidence show about this particular product—and what does it not show?”
This article is for general education and does not provide individualized medical advice. NAD+ testing and supplementation may not be appropriate for everyone. Medical history, medications and clinical circumstances should be reviewed with a qualified healthcare professional.
