IV NR infusions finish faster and cause milder symptoms than IV NAD+ in a real-world clinic

Why it matters: NAD+ levels fall with age, and replenishing them is a popular longevity strategy. Commercial clinics increasingly sell intravenous NAD+ and, more recently, intravenous nicotinamide riboside (NR), mostly without human data on how they compare. The two behave differently in the body. NAD+ itself is poorly taken up by cells and can act as a pro-inflammatory 'danger signal' outside them. NR is a smaller precursor that cells absorb directly. Clinicians and patients have long reported nausea, cramping, and malaise with IV NAD+, which is why it is often infused slowly.

What was studied: The authors retrospectively reviewed electronic medical records from a commercial hyperwellness clinic in Austin, Texas. Adults received four consecutive days of 500 mg IV NAD+ or IV NR, with follow-up at 30 days. The clinic excluded anyone who was pregnant or had a personal or family history of cancer. Baseline fasting bloods were drawn 1 to 4 days before the first infusion. Primary outcomes were reported symptoms, total infusion time, blood pressure, resting heart rate, and safety biomarkers (ALT, AST, hsCRP, BUN/creatinine, TSH). Exploratory outcomes were HbA1c, fasting glucose, HDL-C, LDL-C, and triglycerides. An institutional review board approved the study as exempt.

Key results: Tolerability differed clearly. NAD+ recipients reported moderate to severe gastrointestinal symptoms, increased heart rate, and chest pressure during infusion. NR recipients reported only minor tingling of the tongue, jaw, and arm, plus mild cramping. All symptoms resolved once the infusion ended. Because of the symptoms, NAD+ infusions took longer, averaging 97 minutes versus 37 minutes for NR. ALT, AST, hsCRP, BUN/creatinine, and TSH did not change significantly in either group. Alkaline phosphatase decreased significantly in the NAD+ group only, and stayed within the normal range. Among exploratory outcomes, HbA1c fell significantly with NR and HDL-C fell significantly with NAD+. Fasting glucose and LDL-C did not change in either group.

Implications: Over 30 days, neither product showed signals of organ, inflammatory, or thyroid harm. NR was much easier to tolerate and faster to administer. That may matter for people who cannot take oral precursors, such as those with gastrointestinal disease, though the paper does not test that population. The HbA1c and HDL-C findings are hypothesis-generating only.

Caveats: This was a retrospective pilot in a commercial setting with no randomization or placebo, and the groups may differ in ways the records do not capture. The reported outcomes did not include direct measurement of NAD+ levels, so the study cannot show whether either infusion raised NAD+ or improved health. The authors also note that dosing and effects beyond 30 days need study. Two authors are affiliated with the clinic that funded the work, and the NR was donated by its manufacturer, although the funders reportedly had no role in the analysis. The full text supplied to me was truncated after the methods section, so this summary relies on the abstract and the portions provided.