5 Biomarkers to Track Before Starting NAD+ Supplements.
By: Dr. Katerina Noel
You Can't Optimize What You Haven't Measured
Starting an NAD+ protocol without baseline biomarkers is like prescribing medication without a diagnosis. In our longevity clinic, this is a non-negotiable principle.
Consumer interest in NAD+ has surged 133% since early 2024, according to NutraIngredients, and NAD+ precursor supplements reached €805 million in 2025. Yet most consumers begin supplementing without a single baseline test. The clinical consensus is clear: personalized baseline panels, not generic dosing, are the gold standard.
What follows is the exact pre-protocol checklist I review, alongside our Medical & Scientific Advisory Board, before recommending any NAD+ protocol. It is designed for women who approach longevity with the same rigor they bring to every health decision.
Biomarker 1: HOMA-IR (Insulin Resistance Index)
HOMA-IR is calculated from a simple formula: fasting insulin × fasting glucose ÷ 405. What makes it powerful is its sensitivity. According to Lamkin Clinic, HOMA-IR can detect insulin resistance 10 to 20 years before a diabetes diagnosis appears on standard bloodwork. Neither HbA1c nor fasting glucose alone catches metabolic dysfunction this early, and most routine panels never include it.
Why does this matter for NAD+ protocols specifically? A 2025 study published in Science showed that NMN supplementation at 250 mg/day for 10 weeks improved insulin sensitivity in prediabetic women, as reported by Lola Health. The mechanism is direct: NAD+ is a critical cofactor in mitochondrial energy metabolism. When NAD+ status improves, cells become more efficient at utilizing glucose and responding to insulin signaling.
For women, this marker carries additional weight. Research published in eBioMedicine found that glucose regulation and physical activity are among the strongest drivers of epigenetic aging in female individuals, making metabolic health a cornerstone of any longevity strategy.
Clinical reference ranges used in practice:
- Below 1.0: Optimal insulin sensitivity
- Above 2.0: Early insulin resistance
- Above 2.9: Significant resistance requiring clinical attention
Test at baseline before starting your protocol, then retest at 3 months and 6 months to track your metabolic response.
Biomarker 2: hsCRP (High-Sensitivity C-Reactive Protein)
High-sensitivity C-reactive protein is the most clinically actionable inflammation marker available, and one of the three biomarkers with the greatest weight in the PhenoAge biological age formula. According to SuperAge App, citing NHANES data, adults with hsCRP below 0.5 mg/L had 30 to 40% lower all-cause mortality over a 10-year follow-up compared to those above 3.0 mg/L.
A 2025 UK Biobank plasma proteomics analysis of 51,904 participants identified inflammation pathways, with CRP as a central node, as key predictors of biological aging trajectory. The NAD+ connection is mechanistic: chronic low-grade inflammation accelerates NAD+ depletion through PARP and CD38 enzyme activation. If your hsCRP is elevated at baseline, your body is burning through NAD+ faster than normal, which means you may need a more aggressive or targeted protocol.
Lowering hsCRP from 3.0 to below 1.0 mg/L can shift your calculated PhenoAge by several years — a measurable, meaningful change in biological age from addressing a single inflammatory marker.
Ranges recommended for longevity purposes:
- Below 0.5 mg/L: Ideal for longevity
- 1.0–3.0 mg/L: Moderate cardiovascular and aging risk
- Above 3.0 mg/L: Warrants clinical investigation
One important note: hsCRP is distinct from standard CRP. Request the high-sensitivity version specifically from your lab or physician.
Biomarker 3: Epigenetic Age (DunedinPACE or GrimAge)
Epigenetic clocks are the most clinically useful tools available in 2026 for measuring whether a longevity protocol is actually slowing biological aging at the cellular level, as outlined by AgeMD. Two clocks stand out. GrimAge predicts mortality risk. DunedinPACE measures the pace of aging in real time, making it particularly valuable for tracking how your body responds to an intervention over months.
The scientific foundation linking epigenetic age to NAD+ is well established. A clinical trial (NCT04220658) conducted by Elysium Health and Duke Clinical Research Institute studied correlations between DNA methylation epigenetic aging and NAD+ levels in healthy volunteers.
The data demands honesty, however. A 2026 Aging Cell study of 4,260 health enthusiasts found that supplement users had lower epigenetic biological age overall, but most NAD+ boosters did not show significant benefits on their own. This reinforces exactly why a pre-protocol baseline is essential: without it, you cannot determine whether a 6-month NAD+ protocol has moved the needle. The test is the proof.
Epigenetic clock testing (through services such as TruAge or the Elysium Index) is now commercially available, though it remains more expensive than standard blood panels. I recommend testing at baseline and again at 6 to 12 months. Consider this the ultimate accountability metric for a serious longevity protocol.
Biomarker 4: Complete Blood Count with RBC Parameters
A standard CBC is one of the most overlooked longevity tracking tools. Beyond basic safety screening, the red blood cell parameters it captures (RDW, hemoglobin, and MCV) offer real insight into how your body is responding to an NAD+ protocol.
Clinical trial data reported by NutraIngredients found that NMN-induced increases in blood NAD were associated with statistically significant improvements in RBC parameters, suggesting enhanced oxygen-carrying capacity. The mechanistic explanation is straightforward: NAD+ is essential for mitochondrial function in red blood cells, and improved NAD+ status may support erythrocyte energy metabolism while reducing oxidative damage.
RDW (red cell distribution width) deserves particular attention. It is one of the three biomarkers with the greatest weight in the PhenoAge biological age formula, alongside glucose and hsCRP. An elevated RDW above 14.5% signals cellular stress and is associated with accelerated biological aging. Optimal hemoglobin, meanwhile, supports energy production and cognitive performance.
The practical advantage of a CBC is substantial: it is inexpensive, widely available, and included in most routine blood panels. This makes it a high-value, low-barrier baseline marker that every woman starting an NAD+ protocol should have on file. I recommend tracking at baseline and again at 60 to 90 days, consistent with the 60-day RCT that demonstrated significant NAD-related RBC changes.
Biomarker 5: Liver Enzymes and Kidney Function (ALT, GGT, eGFR)
This is the safety and efficacy biomarker, and it is essential for any woman on a premium supplement stack. In clinical practice, I consider it a trust-building standard: we never recommend a protocol without confirming hepatic and renal tolerance first.
ALT and GGT measure hepatic stress and detoxification capacity. GGT is also an independent predictor of oxidative stress and metabolic syndrome, giving it dual relevance for longevity assessment. Clinical evidence from completed human trials, as reviewed by Lola Health, shows that NMN supplementation has been shown to improve or stabilize ALT and GGT, meaning these markers serve as both safety checks and efficacy indicators.
Estimated glomerular filtration rate (eGFR) rounds out this panel as the kidney function marker. NAD+ metabolism produces byproducts that are cleared renally, so baseline kidney function directly informs safe dosing and protocol design.
A 2026 PRISMA-guided systematic review confirmed that human effects of NMN and NR on metabolic and hepatic outcomes remain mixed. This is precisely why individualized baseline data matters more than population-level assumptions. Liver enzyme elevation can result from many factors: alcohol, medications, fatty liver disease. Baseline testing distinguishes pre-existing conditions from any supplement-related changes.
I recommend ALT, GGT, and eGFR at baseline, then repeat at 3 months to confirm your body is tolerating the protocol well.
How to Use These Biomarkers: A Retesting Framework
The retesting timeline I use in practice:
- Baseline: Complete panel (all five biomarkers) before starting your NAD+ protocol
- 3 months: Retest metabolic and safety markers (HOMA-IR, hsCRP, liver enzymes, CBC)
- 6 months: Comprehensive review including epigenetic clock testing for cellular-level evidence
One variable worth noting: research presented at a March 2026 NAD+ conference at the University of Copenhagen found that most oral NMN and NR is converted to niacin by gut bacteria before absorption, as reported by Supply Side SJ. This means gut health status may influence who responds best and should be considered in protocol design.
The personalization principle is critical. The 2026 PRISMA review confirmed that human metabolic and vascular responses to NMN and NR remain highly variable. These five biomarkers are the clinical tools that transform a generic supplement into a personalized protocol. At Dr. Noel, our approach integrates these markers into a structured longevity system combining pharmaceutical-grade NMN formulations, produced in Germany with third-party testing, alongside evidence-based inner and outer care.
The Bottom Line: Test First, Then Supplement
NAD+ supplementation is one of the most evidence-supported longevity interventions available in 2026. Its benefits are dose-dependent and individual-dependent. Baseline biomarkers are the clinical foundation that separates a thoughtful protocol from guesswork.
To summarize the five markers:
- HOMA-IR for metabolic sensitivity and early insulin resistance detection
- hsCRP for inflammatory burden and biological age calculation
- Epigenetic clock (DunedinPACE or GrimAge) for cellular aging pace
- CBC with RBC parameters for mitochondrial function and oxygen-carrying capacity
- Liver enzymes and eGFR for organ safety and protocol tolerance
This is the standard I apply in my own practice. It is not a marketing checklist. It is a clinical commitment to precision and personalization, developed alongside our Medical & Scientific Advisory Board of specialists in dermatology, genetics, and longevity medicine.
Before starting any NAD+ protocol, request these specific tests from your physician or longevity clinician. Bring your results, ask questions, and build your protocol on data rather than assumptions. If you would like a guided pre-protocol biomarker assessment or want to explore our pharmaceutical-grade longevity formulations, we are here to help you begin with the clarity you deserve.
Sources
- NutraIngredients — NAD+ Supplement Market Analysis (2025)
- Future Market Insights — NAD Precursor Supplements Market Report (2025)
- Lamkin Clinic — HOMA-IR: Optimal Levels and Reference Ranges (2026)
- Lola Health — NMN Blood Test: Is It Working? (2026)
- eBioMedicine / PMC — Epigenetic Clocks and Lifestyle Factors (2026)
- SuperAge App — hsCRP: The Inflammation Marker That Predicts Biological Aging (2026)
- AgeMD — Epigenetic Clocks: Advancing Biological Age Measures (2026)
- ClinicalTrials.gov — Elysium Health / Duke Epigenetic Aging and NAD+ Trial
- Aging Cell — Supplements and Biological Age in Health Enthusiasts (2026)
- PMC — Efficacy and Safety of NMN Supplementation RCT
- ScienceDirect — NAD+ Supplementation PRISMA-Guided Systematic Review (2026)
- Supply Side SJ — NAD+ Supplements: Science and Formulation Insights (2026)