NMN dosage and evidence

Overview

Mechanism of action

Converts to NAD+ through the salvage pathway, aiming to restore NAD+ levels that decline with age.

Human evidence

Blood NAD rises. Function mostly does not. The one positive insulin result is in a narrow group. The function trials in older or heavier adults are mixed or null.

• Yoshino 2021: 10 weeks, 250 mg/day, overweight or obese postmenopausal women with prediabetes. Muscle insulin sensitivity rose. Other metabolic outcomes did not.
• Yi 2023: 60 days, 80 adults, 300 to 900 mg/day. Blood NAD rose. Six-minute walk improved modestly. HOMA-IR did not.
• Akasaka 2023: 14 older men with diabetes and poor performance, 250 mg/day for 24 weeks. Grip and walking speed did not separate. Teijin funded.
• MIB-626 2023: 30 overweight or obese adults, 1000 mg twice daily for 28 days. Weight, diastolic pressure and LDL fell. Muscle function and insulin sensitivity did not. Maker funded.

What this does not tell you: No trial has tested whether NMN slows ageing in a person. The walk-distance and weight findings are short, small, and in some cases funder-tied. A blood NAD rise is not a clinical result.

The evidence, charted

Key studies & citations

• Human2021
  Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women

  NMN improved one thing in one narrow group of people, and left everything else alone. The women taking part were past menopause, carried extra weight and had blood sugar creeping towards diabetes. Half took NMN daily for ten weeks, half took a dummy pill, and nobody involved knew which. Muscle became more responsive to insulin in the NMN group. Nothing else the researchers measured changed. This was a small study in one kind of person, so it says nothing about men, or about anyone healthy.

  10-week RCT in overweight or obese postmenopausal women with prediabetes: 250 mg/day NMN increased muscle insulin sensitivity and insulin signaling versus placebo; other metabolic outcomes did not change.

  PMID 33888596 Science
• Human2023
  The efficacy and safety of beta-nicotinamide mononucleotide (NMN) supplementation in healthy middle-aged adults: a randomized, multicenter, double-blind, placebo-controlled, dose-dependent clinical trial

  NMN raised NAD in the blood and added a little to how far people could walk, and did nothing for blood sugar handling. Eighty healthy middle aged adults took one of three daily doses or a dummy for two months, and nobody involved knew which. Walking distance in six minutes improved modestly. Insulin resistance did not budge. Most people took it without trouble. Two months is short, walking distance is easy to improve, and nobody was followed long enough to see whether anything lasted.

  60-day RCT in 80 adults: 300 to 900 mg/day raised blood NAD and modestly improved six-minute walk distance; well tolerated; HOMA-IR unchanged.

  PMID 36482258 GeroScience
• Animal2016
  Long-term administration of nicotinamide mononucleotide mitigates age-associated physiological decline in mice

  12 months of oral NMN in ageing mice improved insulin sensitivity, energy metabolism, physical activity and eye function without obvious toxicity.

  PMID 28068222 Cell Metabolism
• Human2023
  Effects of nicotinamide mononucleotide on older patients with diabetes and impaired physical performance: a prospective, placebo-controlled, double-blind study

  In the people who most look like a longevity customer, NMN did not move function. 14 older men with diabetes and weak grip or slow walking took 250 mg a day, or a dummy, for 24 weeks. Grip and walking speed did not separate. The study was funded by Teijin. 14 people is tiny, and a null in a tiny study is still the only function result in that group.

  14 older men with diabetes and impaired physical performance, mean age 81.1, randomised to NMN 250 mg/day or placebo for 24 weeks. Grip-strength change 1.25 kg versus -0.44 kg, walking speed 0.033 versus 0.014 m/s, neither significant. Funded by Teijin Ltd.

  PMID 36443648 Geriatrics and Gerontology International
• Human2023
  Nicotinamide adenine dinucleotide augmentation in overweight or obese middle-aged and older adults: a physiologic study

  A high dose NMN tablet raised blood NAD and moved weight and lipids, and left muscle function alone. 30 overweight or obese adults took MIB-626, 1000 mg twice a day, or a dummy, for 28 days. Weight fell 1.9 kg. Diastolic pressure and LDL fell too. Strength, tiredness, aerobic capacity and stair power did not. Insulin sensitivity did not. The maker funded it.

  30 overweight or obese adults aged 45 and over randomised 2:1 to MIB-626 (microcrystalline NMN) 1000 mg twice daily or placebo for 28 days. Weight -1.9 kg, diastolic BP -7.01 mmHg, LDL -18.73 mg/dL versus placebo. Muscle strength, fatigability, aerobic capacity and stair-climbing power did not differ. Insulin sensitivity unchanged. Funder: Metro International Biotech.

  PMID 36740954 Journal of Clinical Endocrinology and Metabolism

What users report

Self-reported experiences, not evidence. Nothing below was measured under controlled conditions, and reports like these cannot separate a real effect from placebo, from the training or diet change that accompanied it, or from what the product actually contained. They are here because knowing what people describe, including what goes wrong, is worth reading alongside the studies.

• The long-running experience threads are dominated by people reporting nothing. Accounts of taking a gram daily for months, of pushing to two grams for a stretch, and of cycling through high, low and no doses while finding nothing that correlates, appear repeatedly and are written by people who wanted it to do something.
• Where people do report a change, it is energy, strength or endurance in training, and the ones reporting it most often are taking it sublingually rather than swallowing it. Whether the sublingual route makes any difference is one of the longest-running arguments in the discussion and is not settled by anyone.
• Doses described range widely, from a few hundred milligrams once a day to several hundred taken repeatedly through the day, and there is no consensus pattern. People adjust up and down largely by feel.
• The negative reported most often is sleep. Taking it later in the day is repeatedly described as producing enough stimulation to prevent sleep or to cause waking in the early hours, and insomnia appearing after several consecutive days shows up as a distinct pattern.
• Worsening tinnitus is raised as a specific complaint by a subset of users, across both NMN and nicotinamide riboside, and is disputed within the same threads.
• Product authenticity is a persistent theme. People describe testing that found a product containing a small fraction of the NMN claimed, describe a flushing reaction and conclude they were sold niacin, and argue that in-house purity certificates with no named laboratory are worthless. Third party HPLC or mass spectrometry testing is treated as the only way to know, and the price a vendor charges is used by some as a rough sanity check.
• Placebo scepticism runs throughout. Longer-standing members regularly point out that the people who report benefit are the people who bought it expecting benefit, and that objection is made by people who take it themselves.

Sources: The NMN personal experience threads, the sublingual route thread, supplier and purity threads, and the NAD+ subforum generally on LongeCity, found by site-restricted search, September 2026. Nothing above is attributed to any specific post and no post is reproduced.