What are the effects if you take NAD every day?
Taking 600-900 mg of a NAD supplement per day raises your NAD levels and provides some benefit for endurance, but long-term safety has not yet been properly studied.
NAD supplements (such as NMN) raise your NAD levels in the blood -- that has been fairly well established. In a randomised, double-blind study of 80 healthy, middle-aged adults, NAD levels rose significantly at all doses from 300 to 900 mg per day after 60 days. Levels were highest at 600 and 900 mg1,2.
In terms of physical effects, participants in all NMN groups performed significantly better on a six-minute walk test than the placebo group, already after 30 days. Those taking 600 or 900 mg also reported a measurably improved sense of health. On blood sugar regulation, the supplement had no demonstrable effect in this study.
A small study of 11 Japanese men taking 250 mg per day confirmed the rise in NAD. In three participants who had excessively high insulin release after meals, that response appeared to decrease slightly, but a group of 11 is too small to draw much from3. For people with chronic fatigue syndrome (ME/CFS), there is moderate support: a combination of CoQ10 (200 mg) and NADH (20 mg) over 12 weeks significantly reduced cognitive fatigue and improved quality of life. This applies specifically to ME/CFS patients only4.
On safety, there are two points. Up to 900 mg per day, NMN was well tolerated in the 60-day study: no side effects or abnormal laboratory values. Laboratory research does reveal a theoretical risk: if the supplement accumulates in tissues and is not converted quickly enough, an enzyme can be activated that breaks down nerve fibres. Whether this occurs in humans during normal use is unknown5. In addition, smokers taking a different NAD precursor showed a dose-dependent increase in a marker for possible DNA instability, without any reduction in smoking-related DNA damage6.
People respond very differently to the same dose: the increase in NAD varied by a factor of three to more than ten within the same dosage group. A single standard dose therefore does not work equally well for everyone. And because all studies lasted a maximum of 60 to 90 days in relatively small groups, we simply do not yet know what daily long-term use does.
All claims are based on two publications from the same study (PMID 36482258 and PMID 38430946, 80 participants), one small open-label study (PMID 38191197, 11 participants), one study in ME/CFS patients (PMID 34444817), one laboratory study on the nerve fibre risk (PMID 36657725), and one older study in smokers using a different NAD precursor (PMID 10030610). The large study is the strongest source, but has a short duration of 60 days and a limited number of participants.
At what age does taking NAD+ supplements make sense?
There is no established age at which NAD+ supplementation becomes worthwhile; studies focus on middle-aged and older adults, but a measurable functional benefit in humans has not yet been demonstrated. Anyone considering starting does so on the most informed basis after middle age, with realistic expectations.
Does NAD+ cause weight gain?
There is no scientific evidence that NAD+ supplements such as NMN or NR cause weight gain. Animal research even suggests the opposite, but this has not yet been confirmed in humans.
Does NAD+ supplementation slow biological ageing?
NAD+ supplements raise your NAD+ levels in the blood, but whether that also means you age biologically more slowly has not been demonstrated in humans at this time. The question is interesting, but firm conclusions cannot yet be drawn; keep an eye on future large-scale research if you are seriously considering this.
Does a NAD infusion (IV drip) make sense?
A NAD infusion has no proven advantage over cheaper oral supplements, and even those show hardly any demonstrable effect in healthy people. Consider an infusion only after consulting your doctor, especially if you have a specific medical condition.
What is NAD+ and what does it do in your body?
NAD+ is an indispensable molecule for energy, DNA repair and cell health, but the question of whether you should actively raise those levels for better health has not yet been answered for humans.
What does NAD+ do for your brain?
NAD+ is biologically crucial for your brain and declines with age, but whether supplementation via NMN or other means genuinely protects humans has not yet been convincingly demonstrated. Wait for the results of larger clinical studies before drawing firm conclusions.