What NAD+ Actually Does (And Why Pills Don't Work)

NAD+ pills are everywhere. Big claims, big price tags, big jars. The catch: oral NAD+ barely shows up in the bloodstream because the molecule doesn't survive digestion. The published plasma data is brutal on that point.

That doesn't mean NAD+ doesn't matter. It does two specific jobs in every cell, both backed by decades of cellular biology research. This piece walks through those two jobs in plain English, why oral forms fail to deliver, why NMN and NR get a more complicated answer, and the standard injection loading protocol researchers use.

What NAD+ actually does

NAD+ (nicotinamide adenine dinucleotide) runs two distinct jobs in the cell.

Job 1: Electron shuttle in the mitochondria

Inside the mitochondria (the cell's power plants), NAD+ accepts electrons during the breakdown of food. When it picks up an electron, it becomes NADH. NADH then drops that electron into the electron transport chain, the process that makes ATP, the cell's energy currency. Every cell needs a continuous supply of NAD+ to keep this loop running.

Job 2: Substrate for three enzyme families

NAD+ is also the raw material for three enzyme families implicated in cellular aging:

• Sirtuins. Seven enzymes implicated in longevity research. They consume NAD+ as part of their catalytic cycle.
• PARPs. DNA repair enzymes. They consume NAD+ whenever DNA damage gets sensed.
• CD38. A surface enzyme involved in calcium signaling and immune function. CD38 expression rises with age and consumes a lot of NAD+.

Across the human lifespan, this balance shifts: synthesis appears to slow, CD38 expression climbs, and net cellular NAD+ levels drop in nearly every studied tissue. That decline is the foundation of the longevity research interest.

Why oral NAD+ pills don't work

NAD+ is a large, charged molecule. The gut is built to break large molecules into small ones for absorption. Stomach acid and gut enzymes hit NAD+ hard. By the time anything reaches the bloodstream, most of the original molecule is gone.

Published plasma data on oral NAD+ pills shows almost no rise in blood NAD+ after dosing. The marketing copy says one thing. The pharmacokinetics say another. Subcutaneous injection sidesteps the gut entirely and produces a measurable plasma rise within an hour.

NMN and NR: the precursor problem

NMN and NR are smaller molecules the body converts into NAD+ through enzyme steps. Both survive digestion better than NAD+ itself. That's why they dominate the oral supplement market.

The catch: conversion efficiency varies a lot person to person. Some people convert NMN to NAD+ well. Others convert poorly because of differences in enzyme expression. The plasma rise in published data is real but smaller and slower than injected NAD+.

For researchers who want a predictable plasma signal, injected NAD+ is the most direct. For researchers who want a daily oral baseline, NMN or NR makes more sense.

What does the NAD+ research signal cover?

Frequently cited research targets in the published NAD+ literature:

• Cellular energy and mitochondrial function research
• Cognitive function research
• Sleep quality research
• Metabolic health research
• Skin and hair research
• Exercise recovery research

The clinical trial dataset is smaller than the weight-loss class and still building. The strongest published evidence supports the cellular energy and mitochondrial function pathway. Downstream outcome research is more variable.

What is the standard NAD+ loading protocol?

Pulse loading (a concentrated burst of dosing followed by a long off-period) is the standard model. Continuous daily dosing gives diminishing returns, likely because cellular NAD+ recycling pathways adapt.

What are the NAD+ side effects from the literature?

• Injection site stinging. Common for the larger NAD+ shot volumes (1 to 2 mL). Slow push over 30 seconds and splitting the dose AM/PM are the standard fixes.
• Mild flushing or warmth. Some researchers report transient flushing in the first 10 to 15 minutes after the shot. Self-resolves.
• Energy or sleep changes. Many researchers note energy or sleep shifts during the loading window. Expected and self-resolves.
• Mild nausea. At doses above 100 mg. Splitting the dose AM/PM usually fixes it.

How do you reconstitute and store NAD+?

Aion ships NAD+ in 500 mg and 1000 mg vials. Standard mix for the 1000 mg vial: 10 mL of bac water, giving 100 mg per mL. A 50 mg dose at that concentration is 0.5 mL. A 100 mg dose is 1.0 mL. Larger volumes need a 1 mL or 3 mL syringe instead of a 0.5 mL insulin syringe. Full walk-through in our reconstitution guide.

• Lyophilized, sealed: refrigerated at 2 to 8 C, stable for months
• Lyophilized, long-term: minus 20 C freezer for multi-year storage
• Reconstituted with bac water: refrigerated at 2 to 8 C, keep out of light, 4 week use window. NAD+ is more temperature-sensitive after reconstitution than most peptides.

What researchers track on an NAD+ loading cycle

1. Subjective energy (1 to 10), morning and afternoon, daily
2. Sleep quality (1 to 10), daily, cross-referenced with wearable scores
3. Resting heart rate, weekly average
4. Cognitive focus self-rating, weekly
5. Wearable recovery score, weekly average

What is the NAD+ bottom line?

NAD+ rewards consistency during the loading window. The 10 to 20 day pulse only works if every day gets hit. Researchers who skip 3 days in a 10-day load lose most of the cumulative effect, because cellular NAD+ recycling pathways run fast and concentration only stays elevated with continuous daily input.

Pick the days, block them on the calendar, handle each injection like an appointment. Pills look easier, but the published plasma data doesn't back them up. For the fullinjection technique walk-through, see /blog/peptide-injection-101.