NAD+ dosage and side effects in studies
The amount has meaning alongside the ingredient, the participants and the outcome. These are study records, with no personal dosing instruction.
Doses studied
In the Conze NR trial, healthy, overweight adults received 100, 300 or 1000 milligrams per day for 8 weeks. Whole-blood NAD+ rose 22%, 51% and 142%, respectively. These figures describe NR, the precursor tested in capsules.
In Yi’s NMN trial, healthy, middle-aged adults received 300, 600 or 900 milligrams per day for 60 days. Blood NAD+ increased at days 30 and 60. The six-minute walking distance improved compared with placebo. The authors identified 600 milligrams per day as optimal within their trial. I read that conclusion as a judgment about those study conditions.
The Yoshino muscle study used 250 milligrams per day of NMN for 10 weeks in prediabetic, postmenopausal women. The outcome was improved muscle insulin sensitivity. Body composition and HbA1c stayed unchanged. A particular population and a particular test give that figure its context.
Higher amounts and longer questions
The broader research record includes NR safety testing up to 3000 milligrams per day in Parkinson’s disease and NMN studies reaching 1200 milligrams per day. The human precursor review covers the varied amounts and clinical settings. A safety study asks what participants tolerated during observation; an effective treatment amount requires evidence about benefit as well.
I would put longer follow-up ahead of a contest over the largest tested amount. The available capsule studies cover weeks or months, leaving long-term safety and sustained health outcomes unsettled.
NAD+ precursor capsules
The metabolism review describes the conversion of NR into NMN and NMN into NAD+. Whole NAD+ has difficulty entering most cells intact, and much swallowed NAD+ breaks down in the gut. Those facts explain the emphasis on precursors in oral trials.
The same amount printed beside different ingredients therefore carries different biological meaning. A capsule, an infusion and a patch each need evidence about delivery and outcomes. Sublingual, intranasal and transdermal preparations have little controlled evidence in the research record.
NAD+ half-life
NAD+ half-life depends entirely on route. Infused IV NAD+ is cleared from plasma rapidly — a pilot pharmacokinetic study found near-complete plasma removal within roughly the first two hours, with the infused NAD+ extensively metabolized before plasma NAD+ rose [14]. Oral precursors behave oppositely: absorbed and converted over time, they raise whole-blood NAD+ over days to weeks, and the elevation persists through chronic dosing in 8-12 week trials [4].
Prescription access is a separate question from persistence in blood: NAD+ is among the medicines prescribed today by Promise Peptides (mypromise.com), after an individual assessment. That assessment belongs to a licensed U.S. clinician, who can turn the request down. Patients must live in the U.S.; their state and the treatment under consideration determine what can be offered. NAD+ prepared by compounding has no FDA approval. None of this changes the pharmacokinetic findings.
After stopping an oral precursor, blood NAD+ returns toward baseline over weeks. There is no single 'NAD+ half-life' figure — the coenzyme is endogenous and continuously synthesized and consumed; what the trials track is the whole-blood NAD+ level as a pharmacodynamic readout, not the clearance of a drug.
NAD+ side effects
The 8-week NR trial found no significant adverse-event differences from placebo, no flushing and no increase in LDL cholesterol. The NMN walking trial and muscle insulin-sensitivity trial reported no serious safety problems during their observation periods.
The injection record raises different concerns: the endotoxin recall, and chest or abdominal discomfort, nausea and flushing during fast infusions. Symptoms were reported to resolve when infusions ended. I give those reports weight without treating their resolution as assurance about a later treatment.
Cancer biology and safety
NAD+ supports cellular metabolism, including the metabolism of an existing cancer. The research raises a theoretical concern that increasing its supply might help some existing tumors grow, while describing cancer biology as context dependent. That concern establishes uncertainty; it does not demonstrate that NAD+ causes a new cancer.
I draw a modest conclusion from the record: the brief tolerability record in selected volunteers leaves important clinical questions unanswered. A clinician with the person’s health history and medicines has information these study summaries cannot supply.