An NMN supplement is a capsule or powder of nicotinamide mononucleotide, a molecule your cells convert into NAD⁺ in a single enzymatic step. Roughly 250 to 1,000 mg a day is what most products sell, and$17 to $249 a month is what the brands we have verified charge. The bottles do not hold the same amount, though, so we also rank them by cost per gram of actual NMN, where the spread is about twenty-fold. This page is about what you get for that, judged by the trials rather than the label.
The short version: the absorption claim is true, the benefit claims mostly are not established, and NMN is still a better buy than an NAD⁺ injection on both evidence and price. Those three facts do not usually appear on the same page.
What the individual trials found
There are more human trials of NMN than skeptics assume and fewer than sellers imply. The strongest is a randomized, double-blind, placebo-controlled, multicenter trial of 80 healthy middle-aged adults (n = 80) on placebo, 300, 600 or 900 mg daily for 60 days. Blood NAD rose significantly in every NMN arm at day 30 and day 60 against placebo and baseline (all p ≤ 0.001), and the increase in six-minute walking distance was significantly greater than placebo in all three dose groups (all p < 0.01) [1].
A Japanese trial gave 250 mg daily to healthy older men for 6 or 12 weeks. Blood NAD⁺ and its metabolites rose significantly; gait speed and left-hand grip showed what the authors themselves called nominally significant improvements needing validation in larger studies; body composition did not change [2]. A second trial of 250 mg daily for 12 weeks in 60 older adults is more instructive still, because of how it is structured: its primary outcome — a stepping test — showed no significant difference from placebo at either 4 or 12 weeks. The results that made the headline, a shorter 4-meter walking time and better sleep quality scores, were secondary [3].
In 48 amateur runners training five or six times a week, six weeks of 300, 600 or 1,200 mg daily raised oxygen uptake and power at both ventilatory thresholds more than placebo in the medium and high dose groups — while producing no difference in VO₂max, oxygen pulse or peak power [4]. A genuinely interesting result, and a narrower one than “NMN improves fitness.”
What happens when you pool them
This is the section other buyer’s guides leave out, and it is the one that should shape your decision.
Eight randomized trials of NMN — 342 mostly non-diabetic middle-aged and older adults, doses of 250 to 2,000 mg daily, 14 days to 12 weeks — were pooled for glucose and lipid outcomes. The meta-analysis found no significant benefit on fasting glucose, fasting insulin, glycated hemoglobin, HOMA-IR or the lipid profile [5].
A separate meta-analysis pooled the muscle outcomes in adults over 60. NMN showed no significant effect on skeletal muscle index (mean difference −0.42, 95% CI −0.99 to 0.14, p = 0.14), grip strength, gait speed (mean difference −0.01, 95% CI −0.08 to 0.06, p = 0.79) or the five-time chair stand test, and the authors concluded that current evidence does not support NMN for preserving muscle mass and function in that age group [6].
And a 2026 review of 15 trials, running to 24 weeks, found NMN well tolerated — no increase in overall, serious or system-specific adverse events, no elevation of ALT or AST — with no significant effect on body weight, BMI, fasting glucose, HbA1c, lipid profiles or systolic blood pressure. Diastolic blood pressure fell slightly [7].
The safety picture
Better than the efficacy picture, which is the usual shape for a supplement. A dedicated safety trial gave 1,250 mg of β-NMN once daily for up to four weeks to 31 healthy adults aged 20 to 65 and found no changes exceeding normal physiological variation across anthropometry, hematology, biochemistry, urine and body composition, and no severe adverse events [8]. That is short-term data in healthy people, not a long-term safety record — see what is and is not known about NAD⁺ safety before you start.
What to look for on a label
Four questions do most of the work, and none of them are about the marketing.
Does the daily dose match a trial dose? The published trials used 250, 300, 600, 900, 1,200 and 1,250 mg daily. A product at 125 mg is below everything that has been studied. We keep the full list, with the trial each number comes from, on the dosage page.
Is the milligram figure for NMN itself? In a proprietary blend, the number on the front is the blend, not the ingredient, and you cannot compare it with anything.
What does it cost per gram? This is the only honest way to compare two NMN products, and it reorders the market when you run it — our price comparison and cost calculator exist for exactly that.
NMN or NR? NR has the longer trial record and a settled regulatory position in the United States; NMN’s status as a lawful dietary supplement ingredient is unresolved, which affects whether you can reliably buy it rather than whether it works. We compare the two directly in NMN vs NR, and Tru Niagen is the NR product whose ingredient most of the published NR research actually used.
Our read
If you want to take an NAD⁺ precursor, NMN is a reasonable thing to take: it is absorbed, it raises NAD⁺, and the short-term safety data is clean. Buy it understanding that the pooled evidence for metabolic, muscular and body-composition benefit in healthy adults is currently null, and that anyone telling you otherwise is quoting single trials and skipping the meta-analyses.
What we would not do is pay four times as much for the same molecule in a syringe. The evidence ranking in this category runs opposite to the price ranking, and the oral precursor page is where that shows up most clearly.