NAD+

NAD+ itself has been given to people in only a few published studies, and the three on file are small. A 2019 pilot infused NAD+ intravenously into 8 healthy men, with 3 more given saline, and tracked what happened to it in blood and urine. A 2026 trial randomized 180 adults with heart failure from ischemic cardiomyopathy to 7 days of intravenous NAD+ or placebo on top of standard therapy. Another 2026 trial randomized 45 adults with sudden sensorineural hearing loss to daily intramuscular NAD+ plus standard treatment or standard treatment alone, and 38 finished follow-up.

Most of what gets called NAD+ research in humans is really research on something else: precursors such as nicotinamide riboside (NR), nicotinamide mononucleotide (NMN), nicotinamide and nicotinic acid (niacin), almost always swallowed. A precursor trial tells you about that precursor. It does not tell you what an NAD+ drip does.

The heart failure and hearing results are genuine signals, in hospital patients, from single-center trials. Not one of the three studies measured energy, longevity or athletic performance.

NAD+ is nicotinamide adenine dinucleotide, a coenzyme found in every cell. Paired with its reduced form, NADH, it carries electrons into the mitochondrial respiratory chain, which puts it at the center of ATP production. It is also used up as a raw material by enzymes that run DNA repair (the PARPs), protein deacetylation (the sirtuins, SIRT1 through SIRT7) and immune signalling (CD38 and CD157).

The body builds most of its NAD+ through salvage pathways that recycle NMN, NR, nicotinamide and nicotinic acid, with a smaller share made from tryptophan. That is why those compounds are called precursors, and why a product sold as an "NAD+ booster" is usually one of them rather than NAD+. NADH, the reduced form, is a separate substance with its own FDA compounding listing.

A Coenzyme That Gets Spent

NAD+ has two different jobs. In energy metabolism it is recycled: it picks up electrons, becomes NADH, passes them on and returns. In signalling it is consumed. PARP-1 breaks NAD+ apart to build ADP-ribose chains at sites of DNA damage, sirtuins burn it to strip acetyl groups from proteins, and CD38 degrades it. When consumption outpaces synthesis, cellular levels fall.

That second job is where the aging hypothesis comes from. The 2018 review by Yaku and colleagues summarizes studies reporting that NAD+ levels decrease with age, and that genetic or nutritional activation of NAD+ metabolism extended lifespan in a range of organisms. Those lifespan results come from model organisms, not people.

What Happens When It Goes Into a Vein

NAD+ carries a net negative charge and cannot drift across cell membranes on its own. In the 2019 infusion pilot, plasma NAD+ did not rise at all for the first 2 hours: the infused molecule was being removed from plasma as fast as it arrived. By the end of the 6 hour infusion plasma NAD+ was up 398 percent, alongside rises of 409 percent in nicotinamide and 393 percent in ADP-ribose, both breakdown products. The authors read that pattern as NAD+ being cleaved by glycohydrolase and pyrophosphatase enzymes, and they recovered NAD+ itself and methylnicotinamide in urine. Only plasma and urine were sampled, so whether infused NAD+ reaches tissues intact, or arrives as fragments that cells rebuild, remains open.

NAD+ marketing leans on a real molecule and borrows evidence from neighbouring ones.

A precursor trial is not an NAD+ trial. Most human headlines labelled NAD+ come from NR, NMN or niacin taken by mouth. In the largest pooled analysis on file, 35 of 40 trials were nicotinic acid, a compound already used to treat dyslipidemia, and the pooled precursors raised blood glucose as well as improving lipids. Crediting those results to an NAD+ infusion borrows evidence from a different molecule given by a different route.

A higher blood level is a measurement, not a benefit. The infusion pilot showed plasma NAD+ up 398 percent by hour 6. It showed nothing about how anyone felt, performed or aged, and it did not sample any tissue.

The decline premise is weaker in human blood than the pitch implies. "Your NAD+ falls with age, so top it up" is the core sales argument. Across seven human cohorts, whole-blood NAD+ did not vary with age or with lifestyle interventions. Tissue levels are a separate question that blood measurements cannot answer, but the simple version of the story did not hold where it was tested.

Hospital results do not transfer to healthy adults. The heart failure result is a 3 point ejection fraction difference at 1 month after a week of IV treatment in damaged hearts, with clinical events not significantly different. The hearing result comes from 38 people in acute hearing loss, with no placebo injection in the control arm. Neither tested a healthy person, and the 2022 meta-analysis found precursors had little effect on healthy participants.

An approval number elsewhere is not a US approval. Both 2026 trials used an NAD+ product carrying a Chinese national drug approval number. No NAD+ product is FDA approved.

Short-term safety where NAD+ itself was given looks clean, and it rests on few people over short exposures. In the infusion pilot no adverse events occurred during the 6 hour infusion; GGT, LD and AST fell slightly and bilirubin rose by 2.75 µmol/L, none judged clinically significant, in 8 treated men. In the heart failure trial one NAD+ patient reported minor dizziness that settled in about an hour, and the drug was stopped as a precaution; one placebo patient had chest discomfort; liver, kidney and glucose values showed no notable change. The hearing trial describes a safety analysis but its published text gives no adverse event counts.

Both randomized trials gave NAD+ as short courses around a hospital stay, so neither speaks to months of repeated use. FDA staff reviewers in 2017 found minimal clinical data for identifying a safe dose of exogenous NAD+, and found the bulk substance degrades with light, moisture, alkaline pH and room temperature. Compounded drugs are not FDA approved, which means FDA does not review their safety, effectiveness or quality before they are marketed.

For tested athletes, the substance is not on the WADA list, but WADA method M2.2 prohibits intravenous infusions or injections above 100 mL per 12 hour period, and IV drips of NAD+ routinely exceed that.

What the evidence shows: NAD+ put into a vein is cleared and broken down quickly, and over several hours raises plasma NAD+ and its breakdown products. In one 180-person trial, a week of IV NAD+ in ischemic heart failure produced a modest ejection fraction gain at 1 month, without a significant change in clinical events. In one 38-person trial in sudden hearing loss, adding NAD+ injections to standard therapy went with more hearing recovery.

What it does not show: any effect on energy, cognition, recovery from training or the pace of aging in healthy people, because no study on file tested NAD+ for those. The precursor literature shows NR and NMN can raise NAD+ with unclear functional payoff, and niacin improves lipids while nudging glucose up.

The realistic reading of an NAD+ drip is a well-understood molecule with poorly tested benefits in healthy people, in a substance that FDA reviewers found breaks down readily outside cold, dry, near-neutral storage.

Not an FDA-approved drug. No NAD+ product is approved in the US. NAD+ sits in FDA's Category 1 for bulk substances nominated for compounding, listed with no route restriction, and that placement confers no approval.

Not interchangeable with NR, NMN or niacin. Those precursors are different molecules, mostly studied by mouth, with their own results and side effects. Their trials do not stand in for NAD+ given by vein or injection.

Not shown to raise energy or slow aging. The human trials of NAD+ itself measured plasma metabolites, heart function in heart failure and hearing in acute hearing loss. None measured how a healthy person feels or ages.

Not a banned substance in sport, though the drip can be. WADA does not list NAD+, but an IV volume above 100 mL per 12 hours is a prohibited method regardless of what is in the bag.

NAD+ is the compound where I most want readers to check which molecule a study actually used. The biology is real and it is central. The step from "this coenzyme matters" to "a drip of it will make you feel younger" skips every link that would need evidence.

What I find most worth knowing is that randomized trials of NAD+ itself now exist, and they were run in hospital patients, not in people chasing energy. The heart failure trial hit its primary endpoint by a modest margin and missed its secondary ones. I take that as a real signal for that population and as nothing yet for anyone else.

Where I stay firm: I am not going to tell you to book an infusion, and I am not publishing protocols. The study that would move me is a placebo-controlled trial of NAD+ in healthy adults with an outcome people actually care about, and it has not been done.