NMN vs NAD+: The Science Behind the Hype

Search for NAD+ supplements and you will find NAD+ itself, NMN, NR and a few others, often with confident claims about what each one does. Here is what NAD+ actually is, why the form you take matters, and what the human research does and does not show.

What NAD+ does

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme found in every cell in your body. It plays a central role in turning food into cellular energy, in DNA repair, and in activating sirtuins, a family of proteins studied for their role in healthy ageing.

NAD+ levels decline with age. That much is well established, though the size of the decline varies between tissues and between studies, and it remains an active area of research. What is better understood is that NAD+ can be raised through supplementation, and that is where precursors come in.

Why you cannot simply swallow NAD+

The NAD+ molecule is large and gets broken down during digestion before it reaches your cells. This is why most research has focused on precursors instead: smaller molecules your body absorbs and then converts into NAD+ internally. The two with the strongest human evidence are NMN and NR.

What the human research shows on NMN

In a randomised, double blind, placebo controlled trial of 80 healthy adults aged 40 to 65, NMN significantly increased blood NAD+ after 30 and 60 days compared with both baseline and placebo. Six minute walking distance also improved compared with placebo. (Yi et al., 2023)

In 42 healthy men aged 65 and over taking 250 mg daily for 12 weeks, blood NAD+ and related metabolites rose significantly. Walking speed and left hand grip strength also improved, though the researchers noted these physical performance findings should be confirmed in larger studies. (Igarashi et al., 2022)

In 60 adults aged 65 to 75, NMN raised blood NAD+ over 12 weeks and walking speed was maintained, while it declined in the placebo group. Participants also reported improved sleep quality. (Morifuji et al., 2024)

A 2021 trial in 25 postmenopausal women with prediabetes found a 43% greater NAD+ response than placebo and approximately a 25% improvement in muscle insulin sensitivity after 10 weeks. Notably, other measures including body composition, blood pressure, blood glucose and blood lipids did not significantly change. (Yoshino et al., 2021)

Pooling the evidence, a 2025 meta analysis of 9 randomised trials covering 412 middle aged and older adults found a statistically significant improvement in gait speed, though the pooled effect was modest and the trials varied in dose and duration. (Wang et al., 2025)

That is a fair summary of where NMN sits: a consistent and repeatable effect on blood NAD+, with early and more modest evidence for physical function.

What the human research shows on NR

NR raises NAD+ as well, and the dose response is unusually clear. In 140 healthy adults aged 40 to 60, whole blood NAD+ increased 22% at 100 mg, 51% at 300 mg and 142% at 1,000 mg after just two weeks, with the increases sustained across the study. (Conze et al., 2019)

NR has also been shown to be well tolerated and to raise NAD+ related metabolites in healthy middle aged and older adults (Martens et al., 2018), and to increase NAD+ metabolites specifically in skeletal muscle (Elhassan et al., 2019).

So which one is better?

This is where most articles pick a winner. The honest answer is that NMN and NR both raise NAD+ in humans, they enter the NAD+ pathway at different points, and no head to head trial has established one as superior for everyday use.

That is why Complete Longevity includes both: 500 mg of NMN and 150 mg of NR in each daily serve. It also includes 100 mg of apigenin, which has been studied as an inhibitor of CD38, an enzyme that consumes NAD+. That research is largely preclinical and direct human evidence for isolated apigenin remains limited, so we include it as a complementary ingredient rather than a headline claim.

What to look for in a NAD+ supplement

Third party batch testing, with results you can actually see. Disclosed doses rather than proprietary blends. Manufacturing to a recognised standard such as GMP. Protective packaging, since NAD+ precursors degrade with heat, light and moisture.

What to realistically expect

Every trial above ran for weeks, not days. Raising NAD+ happens relatively quickly, but the downstream measures researchers tracked took 8 to 12 weeks to show. Supplements also work alongside sleep, movement and diet, not instead of them.

If you are taking medication or have a medical condition, speak with your healthcare professional before starting any supplement.

The bottom line

NAD+ itself does not survive digestion. Precursors do. NMN and NR both have human evidence behind them, and they are complementary rather than competing. Look at the dose, look at whether it is disclosed, and look at whether the brand can show you its testing.

Keeper Complete Longevity brings 500 mg of NMN and 150 mg of NR together with 16 other ingredients in one daily serve. Every active ingredient and dose is disclosed, and every batch is independently tested. You can read every study behind the formula on our Clinical Studies page.