One of the most overlooked signs of good metabolic health is muscle mass. Those with more muscle live longer. It’s one of the strongest predictors of longevity. Muscle is a metabolic organ. If you have good muscle growth in the body, you have good mitochondria numbers too.

A new study looked at NR and its effects on NAD+ and muscle mitochondria. 24 sets of twins were included in the study, both men and women around 40 years of age. They were given increasing doses of NR from 250mg-1000mg over the course of a 5-month study. This is one of the longest studies conducted on NR.

They discovered that participants saw an average 230% increase in NAD+ levels. This rise fuels NAD+ Benefits throughout the body. Moreover, muscle samples showed an increased number of muscle stem cells and more mitochondria.

It turns out that NR and its boost in NAD+ may also be a significant factor in the promotion of mitochondria in muscle. In doing so it may promote muscle mass and add another mechanism to its support for longer lifespan.

There are many ways in which NR supplementation may improve health. But how well does it really work? Let’s explore in more detail.

Many of NR’s potential benefits are based on the theory that it can increase NAD+ levels in the body. A 2024 study published in Magnetic Resonance in Medicine explored this theory.

●  Ten healthy volunteers took part in the study.
●  Participants received magnetic resonance imaging (MRI) brain scans twice: after fasting overnight and four hours after taking 900 mg of NR.
●  They also had two further scans without taking NR.
●  There was a consistent increase in NAD+ concentration after NR supplementation in all participants, which ranged from 7% to 40%.
●  On average, cerebral NAD+ levels were 16% higher after NR supplementation.
●  The scans without NR showed no significant changes in NAD+ levels.

This study suggests NR effectively raises levels of NAD+ in the brain. However, the small study size means further research is needed to confirm this.
A 2019 study published in Cell Reports explored the use of NR supplements for older adults. Subjects included 12 men aged 70–80 who were marginally overweight but otherwise healthy.

They received 1 g per day of NR for 21 days, and the study was placebo-controlled. Researchers found that the protocol:

●  Boosted levels and activity of all molecules related to NAD+
●  Did not change how mitochondria in skeletal muscle produced and used energy
●  Reduced proinflammatory molecules in the blood

This suggests that by improving NAD+ availability in the body, NR may reduce the risk of chronic diseases and decrease inflammation, improving health. However, this sample size was very small, so further research is needed to prove this theory.

There’s good news when it comes to NR — in clinical studies thus far, it was not associated with any severe side effects. This sets it apart from other NAD+ precursors, such as nicotinamide and niacin, which are linked to painful flushing sensations and potentially toxic effects.

A 2019 study published in Scientific Reports, consisting of 140 healthy male and female participants, explored the safety of NR as a long-term supplement. This randomized, double-blind, placebo-controlled study tested the safety and effects of different doses of NR over eight weeks.

No flushing was reported, and no significant differences in adverse events were noted between NR and placebo-treated groups and between groups taking different NR doses. The daily doses tested were 100 mg, 300 mg, and 1,000 mg.