What are the effects if you take NAD every day?

NMN (nicotinamide mononucleotide) is the most extensively studied NAD precursor in supplement form. In a randomised, double-blind, placebo-controlled trial with 80 healthy middle-aged adults, daily intake of 300 to 900 mg NMN for 60 days significantly increased NAD concentrations in the blood at all doses. NAD levels were highest at 600 and 900 mg per day. The evidence that this supplement produces this basic effect is therefore fairly well established for this dose and duration.

On the physical side, participants in all NMN groups showed a significant improvement in a six-minute walk test compared with placebo, already after 30 days and even more clearly after 60 days. Those taking 600 or 900 mg per day also reported a measurably better perceived health on a validated questionnaire (SF-36). NMN had no demonstrable effect on insulin resistance in this trial. In short: for physical endurance and wellbeing there are positive signals from one well-designed trial, but for metabolic effects such as blood sugar regulation the picture is less promising.

A smaller open-label study with 11 healthy Japanese men taking 250 mg NMN per day for eight weeks confirmed the rise in NAD in blood cells. In three participants with excessive post-meal insulin secretion, the insulin response appeared to decrease somewhat, but with such a small group this amounts to no more than a cautious indication.

For a specific patient group, namely people with chronic fatigue syndrome (ME/CFS), there is moderate support for a combination of CoQ10 (200 mg) plus NADH (20 mg, a directly related form of NAD) for 12 weeks: cognitive fatigue decreased significantly and quality of life improved. This applies explicitly to ME/CFS patients and not to healthy individuals.

On safety there are two sides. On the one hand, NMN up to 900 mg per day was well tolerated in the 60-day trial: no side effects or abnormal laboratory values. On the other hand, there is a theoretical concern from laboratory research: if NMN accumulates in tissues and is not converted to NAD quickly enough, it can activate an enzyme (SARM1) involved in the breakdown of nerve fibres. Whether this poses a problem with normal supplement use in humans is unknown. Long-term safety in humans has not yet been sufficiently studied. Furthermore, in smokers taking nicotinic acid (another NAD precursor), a dose-dependent increase in a marker of possible DNA instability was found, without any reduction in smoking-related DNA damage. The clinical significance of this is unclear, but it illustrates that more NAD precursor does not always have a neutral outcome.

Finally, there is an important practical point: people respond very differently to the same NMN dose. The degree of NAD increase within the same dosing group varied by a factor of three to more than ten. A fixed standard dose therefore does not work equally well for everyone; measuring NAD in the blood can help determine the right amount for each individual. Current studies cover a maximum of 60 to 90 days in relatively small groups, so we still know little about what daily intake does over the long term.