You sleep as much as you used to. Still, your energy runs out at three in the afternoon, and a hard week takes longer to recover from. Part of the explanation sits in your cells, and that part can be addressed.
Every cell in your body contains a molecule called NAD. It is needed to convert the food you eat into energy, and for several of the processes that keep cells running over time. The problem is that levels decline with age.
In short
What is NAD?
NAD stands for nicotinamide adenine dinucleotide. The name is complicated. The function is simpler.
NAD is a coenzyme, a molecule other enzymes need to do their job. Its most important task is helping cells convert food into usable energy. NAD⁺ is also used by enzymes that handle cell signaling, stress response and DNA repair, such as the sirtuins that have drawn so much attention in aging research.
As we age, many of the systems that keep cells running change: energy metabolism, repair, and how the body handles cellular stress. NAD is involved in all three. That is why researchers have spent the past decade investigating whether NAD levels can be influenced in humans.
Can NAD be raised? Yes.
The body makes NAD⁺ from building blocks called precursors. The best studied in humans is NR, nicotinamide riboside.
In a randomized, double-blind, placebo-controlled study, participants took 100, 300 or 1,000 mg of NR a day. After two weeks, blood NAD⁺ had increased in every group.
Dose-dependent
Sustained
Measurable
Source: Conze et al., Scientific Reports, 2019. Randomized, double-blind, placebo-controlled.
Why isn’t more NR enough?
Most NAD supplements do one thing: top up, with NR or NMN. But the body also breaks NAD⁺ down. The enzyme CD38 becomes more active with age and consumes NAD⁺ faster than the top-up can replace it.
Think of NAD as water in a bucket. Pouring in more doesn’t help if the bucket leaks.
So Nexus does four things at once, with seven active ingredients in one capsule.
Raise
Protect
Activate
Sustain
When will you notice something?
Blood NAD⁺ is measurable after two weeks. But NAD is not a stimulant where an immediate feeling is the proof. Here is how our customers describe it:
Most notice stamina and alertness first. This is where the difference starts to show in everyday life.
Focus that lasts through the afternoon. Fewer days needed to recover.
After three months the body has had time to adapt. Many notice a difference in how their skin looks and feels. This is where we measure.
Customers who tried stopping.
The best test of a supplement is taking it away. Several of our customers have done exactly that.
“Felt more alert and sharper in the head after about 3 weeks. Tried a month without, and after about 3 weeks I felt a drop in well-being and energy. Now I’m into my second month and have kept the focus and clarity.”
“Noticed a change in my training and energy levels fairly quickly. Then a two-month break to rule out placebo. In short: there was a clear difference on and off Nexus.”
“Over several years I have both taken Nexus regularly and compared how I feel without it. Nexus is the one supplement I can’t be without. The effect comes gradually.”
Four questions before you decide.
Are there side effects?
NR has been studied in several controlled human trials and was well tolerated at the doses studied, including in middle-aged and older adults. Stick to two capsules a day. If you are pregnant, breastfeeding, have a medical condition or take medication, consult your healthcare provider first.
Is there research behind it?
Yes. Over 10,000 scientific papers on NAD have been published in the past five years. The studies we rely on are listed at the bottom of the page. Ingredients are tested at external laboratories, including Intertek, and test reports are available on request.
Am I locked into anything?
No. No binding period, no notice period. Pause or cancel your subscription whenever you like, at no cost.
What if I don’t notice a difference?
Then get in touch after 90 days and we refund you. No questions, no returns. We take the risk, because we know most people notice a difference once the body has had time.
Best in test.
Best in test among NAD+ supplements.
Testproffs 2026Best premium. “Broad NR formula with clearly declared ingredient amounts.”
Kostnord 2026
Conze D, Brenner C, Kruger CL. Safety and Metabolism of Long-term Administration of NIAGEN (Nicotinamide Riboside Chloride) in a Randomized, Double-Blind, Placebo-controlled Clinical Trial of Healthy Overweight Adults. Scientific Reports. 2019;9:9772.
Martens CR et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nature Communications. 2018;9:1286.
Migaud ME, Ziegler M, Baur JA. Regulation of and challenges in targeting NAD+ metabolism. Nature Reviews Molecular Cell Biology. 2024;25:822–840.
Kellenberger E et al. Flavonoids as inhibitors of human CD38. Bioorganic & Medicinal Chemistry Letters. 2011;21(13):3939–3942.
ᵃ Ongoing observational study based on 503 customer reviews collected after 3 months of use. ᵇ Repurchase rate calculated across the entire customer base, excluding new customers from the past 30 days. Niacinamide, vitamin B6, B12 and folate contribute to normal energy metabolism and the reduction of tiredness and fatigue.
