What Is NAD? The Coenzyme That Is Not a Peptide

NAD is sold alongside peptides, bundled into peptide menus and discussed in peptide clinics, which has produced a widespread and understandable misconception. It is worth clearing up before anything else, because it changes how the molecule is regulated, how it is dosed and what you can honestly claim about it.

Dr. Chris Croley, Empire's Chief Medical Officer, puts it plainly: “It's technically a coenzyme. No, it's not a peptide. But it's often sold with peptides and peptide categories. It's used as an adjunct to a lot of peptide therapy.”

What Is NAD, and Why It Is Not a Peptide

A peptide is a short chain of amino acids. NAD — nicotinamide adenine dinucleotide — is not one. It is a coenzyme: a helper molecule that enzymes require in order to do their work.

The distinction matters for three practical reasons:

• Regulatory status differs. NAD is not an FDA-approved drug for a cosmetic or longevity indication, but it is an approved coenzyme and it can be compounded. That is a different position from an unapproved research peptide.
• The mechanism is different. Peptides act as signals at receptors. NAD is consumed in metabolic reactions — it is closer to a substrate than a message.
• The claims you can defend are different. Borrowing a peptide's evidence base for NAD, or the reverse, is how clinics end up saying things they cannot support.

What NAD Actually Does in the Body

The short version: NAD is fuel handling for the mitochondria.

“It basically is fuel for the mitochondria,” Croley explains. “It helps convert food into energy. It's in all the cells in our body. And we know with age, with chronic illness, any kind of even acute illness, we get declines in our NAD levels.”

That much is well established. NAD participates in the reactions that turn what you eat into usable cellular energy, it is present in every cell, and measured levels fall with age and with illness.

Do NAD Benefits Follow From Raising Your Levels?

This is the honest gap, and it is the question most marketing skips.

Levels decline with age and illness. It does not automatically follow that putting the level back up reverses the condition that lowered it. Croley is direct about the limit of what is known: “The question is, does just replacing that, does just increasing it or raising those levels change that condition or mitigate that condition? And I don't think we really know the answer to that yet.”

What can be said, carefully:

• People report feeling better. “Through some smaller trials, through lots of anecdotal data and patient case reports, people subjectively feel better,” Croley says. Subjective improvement is real to the patient and it is also the weakest form of evidence. Both things are true.
• Symptom-level findings exist without disease-level ones. His worked example is Parkinson's disease: “If we know in Parkinson's NAD levels are decreased, if we just increase NAD levels, do we reverse Parkinson's? Probably not.” But there are scales showing reduced tremor. A measurable effect on one symptom is not a treatment for the disease.

That distinction — symptom versus disease, subjective versus measured — is the whole of honest NAD counselling.

What NAD Is Used For

In practice, the common uses cluster into a few groups. Their evidence quality is not equal.

• Addiction and withdrawal support. The best-studied use. It has been used in inpatient rehabilitation to reduce cravings, historically by IV infusion.
• Energy and fatigue. The most common request, and largely supported by subjective report.
• As an adjunct to GLP-1 therapy. Croley notes its use in patients on peptides for weight loss “to help that energy, the conversion of food to fuel.”
• Sleep-wake regulation. Including in some early cognitive-decline patients in his practice.

Where it sits in the wider framework matters too. Empire's founder, Dr. Stephen Cosentino, sorts this whole category into proven, plausible and promoted. Asked where NAD falls, Croley placed it toward the proven end rather than the hype end — an approved coenzyme, compoundable, with well-studied conditions behind it — while noting there is no clear FDA-approved indication with it. “We have more science on that than we do much of the other peptides per se that are out there.”

NAD vs NMN: Precursors and the Oral Question

The reason NMN and NR come up constantly is absorption.

NAD is a large molecule. Whether a meaningful amount survives oral administration is a genuine open question, which is why IV delivery became the default for serious dosing and why precursors exist at all. NMN and NR are precursors — the body converts them onward toward NAD — and as Croley puts it, “they're probably better orally.”

The practical trade-off:

• IV NAD delivers high doses reliably, and is cumbersome and slow.
• Oral NMN or NR is convenient, and asks you to accept a conversion step and a less certain dose at the target.
• Sublingual and strip formats sit in between. Croley uses an oral strip combining NMN and NAD when travelling, and IV when at home.

Anyone claiming a settled answer on oral NAD bioavailability is ahead of the evidence.

What This Means for Your Practice

Four things follow for a clinic offering NAD:

1. Stop calling it a peptide. It is a coenzyme. The category error travels into consent forms and marketing copy.
2. Separate the subjective from the measured when you counsel. Patients commonly feel better; that is worth saying, and it is not the same as saying the underlying condition changed.
3. Match the route to the goal. Loading for a chronic condition is a different proposition from a maintenance strip.
4. Do not import evidence across molecules. NAD, NMN and NR are related but not interchangeable, and the data on one does not transfer to another.

Dosing, loading schedules and the infusion protocol are covered separately in NAD IV therapy dosing. Empire teaches infusion protocols in IV nutrition therapy and covers the wider category in the anti-aging and regenerative medicine academy.

Frequently Asked Questions

Is NAD a peptide?

No. NAD is a coenzyme — nicotinamide adenine dinucleotide. Peptides are short chains of amino acids. NAD is frequently sold alongside peptides and used as an adjunct to peptide therapy, which is where the confusion comes from, but it is a different class of molecule with different regulation and a different mechanism.

What does NAD do?

It functions as fuel handling for the mitochondria, participating in the reactions that convert food into cellular energy. It is present in every cell, and levels decline with age, chronic illness and acute illness.

What are the benefits of NAD?

Patients commonly report improved energy and general wellbeing, supported by smaller trials and case reports rather than large controlled ones. The best-studied clinical use is in addiction and withdrawal support. Whether raising NAD levels reverses the conditions associated with low levels is not established.

NMN vs NAD — which is better?

They are not competing versions of the same thing. NMN is a precursor the body converts toward NAD, and precursors are generally considered better suited to oral administration. NAD itself is a large molecule with an unsettled oral bioavailability picture, which is why IV delivery is used for higher doses.

Is NAD FDA approved?

It is not an FDA-approved drug for a longevity or cosmetic indication. It is an approved coenzyme that can be compounded, and it has well-studied uses, most notably in substance-use treatment. Claims should be framed accordingly.

Disclaimer

This article is educational and intended for licensed clinicians. It is not medical advice and does not establish a clinician-patient relationship. NAD is not FDA approved to treat, cure or prevent any disease. Protocols described reflect the clinical practice of the faculty member quoted and are not a recommendation for any individual patient. Treatment decisions should be made by a qualified clinician who has examined the patient.

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