The Molecule You're Running Out Of — And Why It's Aging You Faster Than Anything Else

By the time you read this, your body has already lost somewhere between 40 and 60 percent of the NAD⁺ it carried when you were twenty years old.

Not gradually. Not imperceptibly. Gone — consumed by the relentless biochemical demands of aging, inflammation, and DNA damage — replaced by a metabolic environment in which the enzymes responsible for energy production, cellular repair, and longevity regulation are running on a substrate that is simply no longer there in adequate supply.

I'm 71. I've spent the last ten months systematically reversing the metabolic consequences of that depletion. And the NAD⁺ protocol I've built — a tripartite delivery system of oral supplementation, transdermal patch, and daily subcutaneous injection — is among the most important things I've added to that effort.

Here's what you need to understand about why.

What NAD⁺ Actually Is

Let's be precise, because the category matters.

NAD⁺ — Nicotinamide Adenine Dinucleotide — is not a supplement trend. It is not a peptide. It is not a hormone or a synthetic pharmaceutical introduced from outside the body. It is a coenzyme — a molecule your body already produces, already depends on in every single cell, and already uses to power over 400 enzymatic reactions spanning energy metabolism, DNA repair, immune regulation, and gene expression.

This distinction is not semantic. When you restore NAD⁺ through supplementation, you are not introducing a novel pharmacological signal. You are restoring a substrate that aging has depleted — giving your body's own molecular machinery back the currency it needs to function as designed. That is categorically different from anything else in the longevity toolkit.

The enzyme families that depend on NAD⁺ tell the whole story. Sirtuins — the proteins David Sinclair at Harvard calls the body's longevity regulators — are completely non-functional without NAD⁺ as their substrate. PARP enzymes, which repair broken DNA strands, consume NAD⁺ directly. The dehydrogenases that power the Krebs cycle and generate ATP in your mitochondria operate through NAD⁺-mediated electron transfer. Deplete NAD⁺, and you don't just slow these systems. You shut them down.

The Decline Is Not Subtle

By your seventies, you are operating with roughly half the NAD⁺ you had at peak biological function. The mechanisms driving this depletion are well-characterized: CD38, a NADase enzyme whose expression increases dramatically with chronic inflammation, destroys NAD⁺ faster than the aging salvage pathway can replenish it. NAMPT — the rate-limiting enzyme of NAD⁺ biosynthesis — declines with age. PARP enzymes, responding to mounting DNA damage, compete with sirtuins for the dwindling NAD⁺ supply. The result is a molecular environment in which the body's own repair and longevity systems are substrate-starved precisely when they are needed most.

The downstream effects are the aging phenotype itself: mitochondrial dysfunction, genomic instability, insulin resistance, cognitive decline, loss of muscle mass, cardiovascular risk elevation, and skin degradation. These are not separate problems. They are a single problem — NAD⁺ depletion — expressed across multiple biological systems simultaneously.

The Tripartite Protocol

I don't approach NAD⁺ restoration with a single supplement. I approach it as a pharmacokinetic engineering problem — how do you maintain elevated intracellular NAD⁺ continuously across a full 24-hour cycle?

No single delivery channel achieves that. So I use three.

Channel 1 — Oral NMN (Nicotinamide Mononucleotide): NMN is a direct NAD⁺ precursor that enters the salvage pathway downstream of NAMPT — the age-related bottleneck — and converts to NAD⁺ via a single enzymatic step. Human trials at Washington University (Yoshino et al., 2021) confirmed that NMN is absorbed intact into plasma and reaches target tissues as NMN, not as a degraded byproduct. Oral NMN provides the foundational baseline layer of the protocol.

Channel 2 — Transdermal NAD⁺ Patch: Applied daily, the patch bypasses gastrointestinal degradation and hepatic first-pass metabolism, delivering NAD⁺ directly through the dermis into systemic circulation over a 12 to 18-hour sustained-release window. It fills the coverage gap that oral NMN's 6 to 8-hour peak cannot address — particularly overnight, when SIRT1-mediated circadian regulation and DNA repair demand is at its highest.

Channel 3 — Subcutaneous NAD⁺ Injection (daily): This is the preeminent channel. Subcutaneous delivery places NAD⁺ directly into well-vascularized tissue, where it is absorbed into systemic circulation within 15 to 30 minutes — no intestinal degradation, no hepatic conversion, no bioavailability loss. It is the closest practical approximation to clinical IV infusion that a daily self-administered protocol can achieve. I initiated this approximately 15 days ago. The subjective cognitive clarity in the morning hours has been the most immediate and notable response of any single protocol addition in ten months.

The three channels work together: injection creates the daily peak, the patch sustains the baseline, and NMN feeds the precursor pool continuously. No 24-hour window without meaningful NAD⁺ elevation.

TMG: The Non-Negotiable Co-Factor

One element of this protocol that most people miss — and that has real consequences when ignored — is methylation support.

When NAD⁺ is consumed by sirtuins and recycled, a portion of the nicotinamide byproduct is methylated and excreted. At therapeutic supplementation doses, this methylation demand draws on SAM — S-adenosylmethionine — the body's universal methyl donor. Deplete SAM, and you create downstream deficits in DNA methylation, neurotransmitter synthesis, and homocysteine clearance.

TMG — Trimethylglycine, also called betaine — donates methyl groups directly via the BHMT pathway, converting homocysteine to methionine and regenerating the SAM pool. I take TMG concurrently with NMN every morning. It is not optional. It is the metabolic infrastructure that makes sustained NAD⁺ supplementation safe and efficient.

What This Does at 71

I came into this protocol insulin-dependent, clinically obese at 255 pounds, with a BMI of 36.5. Ten months later: HbA1c of 6.0 percent trending toward the normal range, 45 pounds of fat mass eliminated, skeletal muscle mass in the HIGH category for any age group, and a composite biological age estimated in the mid-50s by multi-domain biomarker assessment.

NAD⁺ restoration is not the only reason for those outcomes. The full seven-pillar protocol — fasting, nutrition, resistance training, Zone 2 cardio, sleep optimization, cold hydrotherapy — is the architecture. But NAD⁺ is the molecular substrate that allows every other pillar to function at its designed capacity. Sirtuins can't deacetylate without it. Mitochondria can't optimize without SIRT3. PGC-1alpha can't complete the Zone 2 cardio mitochondrial biogenesis signal without SIRT1. The entire system depends on it.

Restoring NAD⁺ at 71 is not supplementation. It is infrastructure maintenance for the biological machinery that everything else depends on.

The full research protocol and white paper are available at www.markskoda.com.

Mark A. Skoda is the Principal Investigator of the Skoda Research Hub longevity protocol and Managing Principal of Nusoma Asset Management LLC. His health optimization case study is under review at BMJ Case Reports. All supplementation and injection protocols are conducted under Vanderbilt University Medical Center oversight. This content is for educational purposes and does not constitute medical advice.