What Is NAD+ and Why Does It Matter?
NAD+ (nicotinamide adenine dinucleotide) is a coenzyme present in every cell of your body. It functions as an essential electron carrier in cellular energy metabolism — specifically in the mitochondrial reactions that convert food into ATP. Without adequate NAD+, your mitochondria cannot produce energy efficiently.
Beyond energy metabolism, NAD+ serves as a required substrate for two protein families central to cellular maintenance:
- Sirtuins (SIRT1–SIRT7): NAD+-dependent deacetylases that regulate gene expression, DNA repair, inflammation, circadian rhythm, and metabolic homeostasis. SIRT1 and SIRT3 have been linked to lifespan extension in animal models. Sirtuins cannot function without adequate NAD+.
- PARPs (poly-ADP ribose polymerases): DNA repair enzymes that consume NAD+ rapidly when activated by DNA strand breaks. As DNA damage accumulates with age, PARP activity increases and can deplete cellular NAD+ — creating a feedback loop where aging causes NAD+ decline, which impairs the very repair mechanisms that fight aging.
The NAD+ Decline Problem
NAD+ levels decline with age in virtually every tissue studied. Data from human skeletal muscle biopsies shows a roughly 50% decline between ages 30 and 60. The cause is multifactorial: increased PARP consumption from accumulated DNA damage, decreased NAMPT enzyme activity, and increased CD38 activity that degrades NAD+. The downstream consequences — reduced mitochondrial efficiency, impaired sirtuin activity, decreased DNA repair capacity, increased inflammation — map directly onto the biology of aging and age-related disease.
Injection vs. Oral Supplement: The Bioavailability Argument
Most consumers encounter NAD+ through oral precursor supplements — primarily NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside). These are converted to NAD+ through the salvage biosynthesis pathway. Injectable NAD+ delivers the coenzyme directly into the bloodstream, bypassing intestinal absorption and first-pass metabolism.
Theoretical advantages of injection: higher peak plasma concentrations, bypasses gut conversion variability (intestinal CD73/NRK enzyme activity varies significantly between individuals), and faster intracellular delivery. Whether these pharmacokinetic advantages translate to meaningfully superior clinical outcomes compared to high-dose oral NMN or NR has not been answered by a head-to-head RCT.
What Human Studies Actually Show
- Yoshino et al. (Science, 2021): 250 mg NMN daily for 10 weeks in postmenopausal women with prediabetes increased skeletal muscle NAD+ and improved insulin sensitivity. Small (n=25) but well-designed RCT.
- Martens et al. (Nature Aging, 2020): NR 500 mg twice daily for 6 weeks reliably increased whole-blood NAD+ by 40–60% in middle-aged to older adults. No significant adverse effects.
- Injectable-specific human data: Limited to case series and observational clinic data. No completed RCT specifically evaluating subcutaneous NAD+ injection exists as of mid-2026.
The honest summary: the cellular and animal biology is compelling. The blood level data is real. The clinical outcome data in humans is promising but thin. NAD+ repletion is an evidence-informed intervention, not a proven treatment.
Infusion Reactions: What to Expect
A common concern with NAD+ injection is rate-dependent reactions — flushing, chest tightness, nausea, and a distinctive pressure sensation. These occur when NAD+ is administered too quickly and resolve when the rate is slowed. At YourMD, compounded NAD+ is dispensed as a subcutaneous preparation (not IV), which has a significantly lower reaction rate. Hydrating well before injection and warming the vial to room temperature further reduce likelihood. Anaphylaxis is rare but has been reported — throat tightening, widespread hives, or difficulty breathing requires calling 911 immediately.
Who Is a Candidate
At YourMD, NAD+ injectable is available to adults who have completed a physician evaluation with no contraindications (no active malignancy, not pregnant), understand that human clinical outcome evidence is limited, and are prepared to follow proper sterile injection technique. NAD+ is not a treatment for any diagnosed disease. Our NAD+ injectable is a compounded sterile preparation from Hallandale Pharmacy (503A, USP <797>-compliant, independent CoA per batch), dispensed as a multi-dose vial for self-administered subcutaneous injection. Pricing starts at $75/month. NAD+ nasal spray (Valiant Pharmacy) is also available as a lower-cost entry option.