Longevity Briefs: Can NMN Supplements Prevent Age-Related Muscle Wasting?

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

Why is this research important: Age related loss of muscle mass (sarcopenia) lowers quality of life among the elderly, increases their risk of falls and bone fractures, and contributes to the development of type II diabetes. This in turn increases the risk of most age-related diseases, including dementia, heart disease and cancer, making sarcopenia a major and often under-appreciated contributor to the ageing process.

NMN, or nicotinamide mononucleotide, is a supplement that boosts levels of NAD+, a molecule that is vital for the health of our cells and is thought to play an important role in the ageing process. NAD+ is needed by the mitochondria (the cell’s power plants) to convert nutrients from food into a form of energy that can be used by the cell. NAD+ is also required for many other important processes in the cell, including the repair of damaged DNA. As we age, levels of NAD+ decline, leading to diseased mitochondria, inflammation and DNA damage, all of which are though to promote ageing. This has made scientists interested in whether NAD+ boosters can reduce various aspects of the ageing process, including sarcopenia.

Recent human trials of the NAD+ booster niacin, aka vitamin B3, have shown promising results. In theory, NMN should work better than niacin because fewer steps are needed to convert it into NAD+, and unlike niacin, NMN doesn’t seem to cause side effects. However, while animal results are promising, few human trials of NMN have been done.

What did the researchers do: In this randomised, double-blind, placebo controlled trial, 42 healthy male participants aged 65 or older were recruited. They were each randomised to receive either a placebo treatment, or to take 250mg of NMN daily for 12 weeks. Researchers collected blood samples and measured various aspects of health and physical function before and after the intervention. These included body mass index (BMI), fat mass, muscle mass, grip strength, gait speed and how quickly participants could stand up from a sitting position.

Unfortunately due to an error by the supplement supplier, data from 11 participants in each group was only valid up until the 6 week mark, because these participants received the wrong supplement at 6 weeks.

Key takeaway(s) from this research: There was no significant difference in muscle mass between those taking NMN and those taking a placebo, however, there was a significant effect on muscle strength. Participants taking NMN experienced, on average, a 10% increase in gait speed and a 6% increase in left grip strength compared with placebo after 12 weeks. Right grip strength and chair stand speed also increased more than in the placebo group, though these changes weren’t statistically significant.

NMN did not significantly improve sensitivity to the hormone insulin (loss of insulin sensitivity drives the development of type II diabetes), nor did it improve blood cholesterol scores. No side effects were reported in the group taking NMN, and blood samples showed that NMN boosted NAD+ levels in their cells.

This study suggests that NMN supplementation can increase muscle strength, but not muscle mass. This is a good thing as muscle strength is what actually matters for quality of life, and is more strongly associated with increased lifespan than muscle mass.

Though NMN didn’t improve insulin sensitivity, this could have been because participants’ insulin sensitivity was normal to begin with. Studies in insulin resistant mice have shown NMN to improve insulin sensitivity, and a recent study found that NMN did increase insulin sensitivity in postmenopausal women with prediabetes. It’s also worth noting that, while an optimal dose for humans hasn’t yet been established, the 250mg dose used in this study is probably at the low end of what is effective and safe in humans. We need larger, longer trials with more diverse participants to confirm the effectiveness of NMN supplementation.