The anti-aging field is evolving rapidly, with a constant stream of promising supplements—rapamycin, metformin, taurine, to name a few. But if we’re talking about "longevity staples," NMN (nicotinamide mononucleotide) is definitely on the list.
As is well-known, the decline in NAD+ (nicotinamide adenine dinucleotide) levels in the human body is a key factor in aging. As a precursor to NAD+, NMN helps boost NAD+ levels and has demonstrated excellent anti-aging effects in numerous studies.
Current research on NMN focuses not only on dosage but also on delivery systems—i.e., how to use NMN for maximum effectiveness. Below is a summary of different NMN usage methods, so we can explore which one stands out as the top choice for extending lifespan.
To ensure ingested NMN delivers optimal results, the administration method is crucial. Proper delivery maximizes NMN’s bioavailability—meaning more active NMN reaches the bloodstream, enhancing the supplement’s effectiveness and bringing more anti-aging benefits to users.
Starting with the most common form, let’s examine the potential bioavailability of 5 key NMN administration methods and determine which is most effective.
01 Capsules: The Mainstream, Beginner-Friendly Choice for Stable Anti-Aging
When it comes to NMN delivery, capsules are the most prominent option. They not only mask NMN’s unpleasant taste but also prevent oral absorption of the supplement—making them convenient and well-accepted by users. Capsules are among the most common NMN supplement forms on the market and the only delivery method repeatedly tested in human clinical trials.
Numerous studies have shown that NMN capsules effectively increase blood NAD+ levels with high bioavailability. They enable good NMN absorption by the body, making them a reliable, efficient choice.
However, the body’s benefits from NMN capsules do not appear to follow a linear pattern. A human clinical study found that increasing NMN capsule dosage from 300mg to 600mg boosted blood NAD+ levels, but a 900mg dose did not further enhance NAD+ levels.
In other words, NAD+ elevation via capsules is limited—it only works within a certain dosage range, and exceeding that range offers no additional benefits.
Figure Note: Effects of different NMN doses on blood NAD+ levels. (Legend: □ Change from baseline to day 30; □ Change from baseline to day 60; Placebo, n = 20; 300mg NMN, n = 20; 600mg NMN, n = 20; 900mg NMN, n = 20; NS = Not Significant; * = Statistically Significant)
Beyond regular capsules, scientists have also tested enteric-coated capsules to improve NMN absorption. These capsules only dissolve at specific pH levels in the intestines, protecting NMN from gastric acid damage and ensuring it reaches the intestines for absorption.
In general drug trials, enteric-coated capsules typically improve bioavailability. However, further extensive testing is needed to confirm whether they can enhance NMN’s bioavailability.
02 Powder: Simple, Fast, and Easy to Absorb—No Extra "Shell"
NMN powder is essentially NMN without the capsule shell. To take it, simply dissolve the powder in water and drink it.
In many mouse experiments, researchers have used NMN powder: they dissolved it in water and fed it to mice. Results showed that NMN powder effectively increased blood NAD+ levels, proving its effectiveness.
When simulating NMN powder’s bioavailability, scientists made a surprising discovery: gastric acid does not significantly degrade NMN. This means NMN does not require special protection when passing through the stomach.
This finding somewhat undermines the need for enteric-coated capsules mentioned earlier—NMN remains unaffected by the stomach even without such protection.
From this perspective, NMN powder and capsules are quite similar. The only difference is that capsules "wrap" NMN to prevent oral absorption of the powder.
If we had to highlight a distinction, it would be user experience. Without a capsule shell, users taste NMN in its original form. However, powder is easier to swallow than capsules, making it a great option for people with swallowing difficulties.
03 Sublingual Administration/Oral Sprays: Skip the "Long Trip" for Faster Absorption
Whether in tablet or powder form, NMN must travel a long path through the body before finally reaching the bloodstream. This prolonged journey causes drug loss and reduces NMN absorption.
The most straightforward way to improve NMN absorption is to shorten its travel path in the body, allowing it to enter the bloodstream faster.
To achieve this, scientists bypassed the gastrointestinal tract entirely and developed oral sprays, which deliver NMN directly into the bloodstream via absorption through the oral mucosa.
Oral sprays have higher requirements for NMN type: regular NMN is in microcrystalline form, while oral sprays use liposomal NMN—made from natural fats.
Liposomes are bubble-like structures that can mimic bodily structures to transport molecules, "fooling" the body’s regulatory systems. As a result, liposomal NMN has better bioavailability and is more easily absorbed than microcrystalline NMN.
Sprays do have a drawback, though: true to their name, the mist dissipates quickly, leading to short drug retention time and generally low dosage.
To address the short retention issue, scientists upgraded this oral absorption method by developing sublingual NMN (in forms like gels, tablets, and powders).
These forms of NMN are more stable and remain in the mouth longer. Additionally, the oral mucosa under the tongue is more effective at facilitating NMN penetration into the bloodstream than other oral areas—making sublingual administration theoretically more conducive to improving drug absorption.
04 Topical Application: Limited Benefits—Skin Gets the Most Anti-Aging Effects
Capsules, tablets, and sprays all aim to deliver NMN into the body for systemic absorption. Beyond these, NMN can also be used topically: dissolved in an oil-based solution and applied to the skin.
Studies have shown that topical NMN reduces inflammation and skin damage in mouse models of eczema. Another study found that topical NMN increases NAD+ levels in skin cells grown in laboratory cultures.
However, this NAD+ elevation is limited—it does not increase blood NAD+ levels. Most NMN is absorbed by the skin, so the skin benefits the most from anti-aging effects.
In contrast, systemic NMN delivery (via other methods) not only boosts blood NAD+ levels but also increases skin NAD+ levels—offering multiple benefits. This makes the effects of topical NMN seem somewhat insignificant.
05 Injections: "Potent" Direct Delivery—A Small "Injury" for Maximum Effect
All the NMN delivery methods mentioned above ultimately aim to increase blood NAD+. So why not take a more direct approach: inject NMN directly into the bloodstream, bypassing all other intermediate steps?
That’s exactly what a team of Japanese scientists did. In animal experiments, they injected NMN into healthy subjects. Results showed that direct injection increased blood NAD+ levels by 20% and reduced blood lipid levels.
Figure Note: Changes in blood NAD+ levels over time after injection.
By bypassing all potential organ barriers and delivering NMN directly into the bloodstream, injections achieve nearly 100% bioavailability—resulting in remarkably significant effects.
However, injections are invasive (requiring skin penetration), which raises safety concerns. While they may work in animal experiments, large-scale promotion in human clinical practice faces considerable resistance.
Many Western celebrities—including the Kardashian family and Justin Bieber—endorse NAD+ injections, calling them fast and effective. In contrast, Charles Brenner, a pioneer in NR (another NAD+ precursor) research, argues that getting an injection is unnecessary when oral NAD+ supplements are available.
With conflicting opinions in the field, NMN injections as a method to boost NAD+ levels are unlikely to become mainstream until a unified consensus is reached.
Summary
With so many NMN administration methods—capsules, tablets, powders, sprays, injections, and topical application—it’s easy to feel overwhelmed. Each method has unique characteristics, and none is clearly superior to the others.
Until a "super delivery system" emerges to dominate the market, each method will continue to serve its purpose. For users, the key is to choose the method that suits you best—after all, the most suitable option is always the best one.