MIB-626
MIB-626, a microcrystalline polymorph of beta-nicotinamide mononucleotide
Written by Aaron CuhaReviewed Sep 2026
Also known as: Microcrystalline NMN, Pharmaceutical-grade NMN, beta-NMN polymorph
The only NMN product with a real randomised trial programme: three placebo-controlled trials totalling about 104 participants, all of which measured blood NAD and safety. It raised blood NAD substantially every time. It did not change muscle strength, aerobic capacity, insulin sensitivity, liver fat, or any marker of kidney injury or inflammation in hospitalised patients.
Overview
MIB-626 is beta-nicotinamide mononucleotide. The molecule is the same one sold in supplement capsules. What Metro International Biotech developed is a specific microcrystalline polymorph, a crystal form, taken through an investigational new drug pathway with proper randomised trials attached. That is unusual in this field and it is the reason this compound gets its own page rather than a line on the NMN page.
The trial programme has produced exactly what a serious pharmacological development programme produces early on, and no more. The pharmacokinetic trial in 32 overweight or obese adults aged 55 to 80 showed that 1000 mg once or twice daily for 14 days raised blood NMN significantly above placebo, with mean AUClast 1.7-fold and 3.7-fold above baseline for the two schedules, and produced substantial dose-related increases in blood NAD. Very little unmodified NMN appeared in urine.
The physiologic study in 30 overweight or obese adults aged 45 and over, at 1000 mg twice daily for 28 days, is the one usually cited as positive. It reported body weight 1.9 kg lower, diastolic blood pressure 7.01 mmHg lower, total cholesterol 26.89 mg/dL lower and LDL 18.73 mg/dL lower. In the same trial, muscle strength, muscle fatigability, aerobic capacity and stair-climbing power did not change, and insulin sensitivity, hepatic fat and intra-abdominal fat did not change in either group. Metro International Biotech is a listed funder.
The third trial is the most informative and the least quoted. 42 adults hospitalised with COVID-19 and acute kidney injury received MIB-626 1.0 g twice daily or placebo for 14 days. Blood NAD rose from about 16 to about 43 micrograms per millilitre by day 14, a substantial and clearly demonstrated biochemical effect. Serum creatinine, cystatin C, kidney injury markers, CRP, IL-6, TNF alpha and disease severity indices did not differ between groups. That is the whole pattern of this category in one trial.
Mechanism of action
The active molecule is beta-nicotinamide mononucleotide, which enters NAD synthesis one step below nicotinamide riboside: NMN is adenylylated by NMNAT enzymes directly to NAD, bypassing the NAMPT step that limits nicotinamide. The proprietary element is formulation rather than pharmacology, a defined microcrystalline polymorph intended to give reproducible, pharmaceutical-grade exposure, which is what allows dose-ranging and regulatory filing in a way a variable supplement powder does not. A 2026 human study raised the alternative possibility that orally administered NMN and NR raise systemic NAD partly through gut microbial conversion to nicotinic acid, which if confirmed would apply to this product as much as to any other oral NMN.
Human evidence
Three randomised placebo-controlled trials totalling about 104 participants. All three measured blood NAD and safety. Two measured physiological or clinical outcomes as well, and those outcomes were mostly unchanged.
- Pharmacokinetics, n=32 adults aged 55 to 80, 14 days at 1000 mg once or twice daily: blood NMN AUClast 1.7-fold and 3.7-fold above baseline, substantial dose-related blood NAD increases.
- Physiologic study, n=30 adults aged 45 and over, 28 days at 1000 mg twice daily: weight -1.9 kg, diastolic BP -7.01 mmHg, total cholesterol -26.89 mg/dL, LDL -18.73 mg/dL.
- Same trial, the part usually omitted: no change in muscle strength, muscle fatigability, aerobic capacity or stair-climbing power, and no change in insulin sensitivity, hepatic fat or intra-abdominal fat in either group.
- COVID-19 with acute kidney injury, n=42, 14 days at 1.0 g twice daily: blood NAD rose from 16.0 to 42.6 micrograms per millilitre, and creatinine, cystatin C, kidney injury markers, CRP, IL-6, TNF alpha and disease severity indices were all unchanged versus placebo.
- Safety across all three trials was good, with no signal that would stop development at these doses and durations.
- The longest exposure in the published programme is 28 days.
What this does not tell you: Every trial is small. The largest is 42 participants and the longest is 28 days, so nothing here speaks to chronic use, and a physiologic study reporting significant changes across four of eight measured outcomes in 30 people is hypothesis-generating rather than confirmatory. The manufacturer is a funder on two of the three and employs authors on two of the three. Most importantly, the outcomes that a person would notice, strength, aerobic capacity, insulin sensitivity, kidney function, inflammation, were measured and did not move, in the trials designed by the people with the strongest incentive to find that they did.
Reading the research record
MIB-626 deserves credit for something rare in this field: it was taken through an IND with genuine randomised placebo-controlled trials, registered, published in real journals, with the negative outcomes reported alongside the positive ones. That is a higher standard than almost any consumer NAD product has met.
What that rigour bought is a clear answer to the biomarker question and no answer at all to the clinical one. The compound raises blood NAD substantially, reproducibly and dose-dependently. In the trial where the investigators had the cleanest possible clinical readout, hospitalised patients with acute kidney injury where creatinine and injury markers are measured every day anyway, the NAD went up almost threefold and every marker of the illness was unchanged. The authors' own explanation is that the NAD rise was too slow, and they propose testing parenteral administration. That is a legitimate hypothesis and it is also the second explanation offered for the second null result in the same programme.
The physiologic study is the one that circulates. Read it carefully. Weight, blood pressure and lipids moved. Strength, fatigability, aerobic capacity, stair-climbing power, insulin sensitivity, liver fat and visceral fat did not. A 28-day study in 30 people that reports several significant changes among many measured outcomes, funded by the manufacturer, is a reason to run a larger trial, not a reason to conclude anything.
Manufacturer funding and manufacturer employment of the authors is the norm in this category rather than an occasional footnote, and it is disclosed on each page here rather than buried. The NRPT trials were funded by Elysium Health with company employees and shareholders among the authors. The MIB-626 trials list Metro International Biotech as a funder with company employees among the authors. The nicotinamide riboside dose-response study was funded by ChromaDex with two company employees as authors. The head-to-head comparison of three NAD boosters was written largely by Nestle Research employees. None of that makes a result wrong. It does mean that the independently funded trials in this field deserve more weight than their size alone would suggest, and the independently funded trials are mostly the negative ones.
The evidence, charted
Fig. 1 · evidence composition
4of 4 citations (100%) are in people
Every citation cited here is Human work; no other study type is cited on this page. This count is of our own citation list and understates any literature larger than the sources we cite.
Fig. 2 · evidence over time
Evidence spans 3 distinct years, 2023 to 2026, counted from the citation list on this page.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four jurisdictions shown. A jurisdiction's classification is a regulatory fact, not a verdict on the science; see Legal status below for the full text and any notes.
Fig. 4 · dose response
No human dose response curve exists
We draw this figure where the data supports it. For this compound in humans it does not, so the panel stays empty rather than borrowing an animal curve and implying it transfers.
Key studies & citations
- Human2023
MIB-626, an Oral Formulation of a Microcrystalline Unique Polymorph of β-Nicotinamide Mononucleotide, Increases Circulating Nicotinamide Adenine Dinucleotide and its Metabolome in Middle-Aged and Older Adults
Randomised, double-blind, placebo-controlled pharmacokinetic trial. 32 overweight or obese adults aged 55 to 80, block randomised and stratified by sex, given MIB-626 1000 mg once daily, twice daily, or placebo for 14 days. Blood NMN on day 14 was significantly higher than placebo, with mean AUClast 1.7-fold and 3.7-fold above baseline for the once and twice daily schedules, and there were substantial dose-related increases in blood NAD. Changes were unrelated to sex, BMI or age. Very little unmodified NMN was excreted in urine. The endpoints are blood metabolites and safety.
Journals of Gerontology Series A - Human2023
Nicotinamide Adenine Dinucleotide Augmentation in Overweight or Obese Middle-Aged and Older Adults: A Physiologic Study
Randomised 2:1, 30 overweight or obese adults aged 45 and over, MIB-626 two 500 mg tablets twice daily for 28 days. Body weight fell 1.9 kg (95 percent CI -3.3 to -0.5, P=.008), diastolic blood pressure fell 7.01 mmHg (-13.44 to -0.59, P=.034), total cholesterol fell 26.89 mg/dL (P=.004) and LDL fell 18.73 mg/dL (P=.007). Muscle strength, muscle fatigability, aerobic capacity and stair-climbing power did not change. Insulin sensitivity, hepatic fat and intra-abdominal fat did not change in either group. Metro International Biotech, the manufacturer, is a listed funder. This is a physiologic study with multiple outcomes rather than a trial powered on one of them.
Journal of Clinical Endocrinology and Metabolism - Human2025
Oral MIB-626 (β Nicotinamide Mononucleotide) Safely Raises Blood Nicotinamide Adenine Dinucleotide Levels in Hospitalized Patients With COVID-19 and Acute Kidney Injury: A Randomized Controlled Trial
NCT05038488. 42 adults hospitalised with COVID-19 and acute kidney injury randomised 3:2 to MIB-626 1.0 g or placebo tablets twice daily for 14 days. Blood NAD rose gradually from 16.0 to 25.5 to 42.6 micrograms per millilitre at baseline, day 5 and day 14, and NAD metabolites rose rapidly by day 3. Serum creatinine, cystatin C and serum markers of acute kidney injury did not differ between groups. Serum CRP, IL-6 and TNF alpha and indices of disease severity also did not differ. The authors attribute the absence of clinical effect to the slow rise in NAD and call for studies of parenteral administration. Two authors are employees of Metro International Biotech and a third is a consultant to the company.
FASEB BioAdvances - Human2026
The differential impact of three different NAD(+) boosters on circulatory NAD and microbial metabolism in humans
Randomised, open-label, placebo-controlled, 65 healthy adults, 14 days. NR and NMN comparably increased circulatory NAD while plain nicotinamide did not do so chronically. Using ex vivo fermentation with human microbiota, the authors found that NR and NMN give rise to nicotinic acid, and that in whole blood ex vivo nicotinic acid is a potent NAD booster while NMN, NR and nicotinamide are not, proposing a gut-dependent mechanism through the Preiss-Handler pathway. If confirmed, this applies to any oral NMN product including this one. Ten authors are Nestle Research employees.
Nature Metabolism
Frequently asked questions
Is MIB-626 different from the NMN I can buy?
The molecule is identical: beta-nicotinamide mononucleotide. The difference is a defined microcrystalline crystal form manufactured to pharmaceutical standards and taken through an IND, which is what makes reproducible dosing and regulatory filing possible. Whether the polymorph produces meaningfully different exposure from a good-quality supplement has not been tested head to head in humans.
What did the MIB-626 trials actually show?
That it raises blood NAD substantially and dose-dependently, and that it is well tolerated at 1000 mg twice daily for up to 28 days. On things a person would notice, one trial found weight, diastolic blood pressure and cholesterol lower over 28 days, and the same trial found no change in strength, aerobic capacity, insulin sensitivity or liver fat. A third trial in hospitalised patients found no change in any marker of kidney injury, inflammation or disease severity despite a near-threefold rise in blood NAD.
Can I buy MIB-626?
No. It is an investigational drug and is not approved or marketed anywhere. Products advertised as MIB-626 are not the investigational product.
Does the FDA decision on NMN apply to MIB-626?
It runs the other way. The existence of an IND for MIB-626 is what triggered FDA's 2022 determination that NMN was excluded from the dietary supplement definition under the drug preclusion clause. FDA reversed that determination in September 2025 on the basis that NMN had been marketed as a supplement before the IND took effect. None of that dispute turned on whether NMN works or is safe, and a regulatory reversal is not a safety or efficacy finding.
Is it worth taking NMN at all based on this programme?
The programme establishes that oral NMN raises blood NAD in people, which was never seriously in doubt. It has not established that raising blood NAD changes anything measurable about how a person functions, and in the one trial with hard clinical markers, it did not.