Maintaining Mighty Muscles: Clinical Study Finds NMN Supplement Boosts Muscle Strength and Performance in Older Men

From the obvious, like walking, lifting, and carrying things, to the less-obvious, like breathing, digesting, and keeping your heart beating, we heavily rely on our muscular system to get through our days. Unfortunately, as early as our 30s, our skeletal muscle strength and mass progressively decrease, with many people losing as much as 5% per decade. This drastic reduction in muscle capacity in older adults leads to a decline in quality of life and independence with an increased risk of frailty, falls, fractures, and mortality.   

Paralleling this decline in muscle strength is a drop in NAD+ levels—a molecule known as a coenzyme that helps every cell in our bodies work correctly, including muscle cells. As older people tend to have reductions in NAD+ levels, replenishing this vital coenzyme through its precursors—like NMN (nicotinamide mononucleotide)—may help prevent muscular decline and diminished physical strength. Recent research published in NPJ Aging proved just that. In this study, researchers out of The University of Tokyo show that older men who supplemented with NMN for 12 weeks experienced significant increases in markers of physical strength and performance, adding to the evidence that NMN can support muscular health with age.

Fighting Age-Related Frailty With NMN

Previous studies have found that supplemental NMN is linked to enhanced muscle growth, endurance, and physical performance. In research from 2021, healthy amateur runners that combined NMN with exercise had improvements in several markers of aerobic function, including skeletal muscle oxygen utilization. 

Other research has found that taking NMN in the afternoon improved lower limb motor function in older Japanese adults. And in animal studies, rodents that combined exercise with supplemental NMN exhibited increased blood flow and running endurance, suggesting that boosting NAD+ can support various aspects of physical performance. 

Now, in this study, Igarashi and colleagues show that supplementing with NMN improved certain aspects of muscle strength and performance in healthy older men. The Japan-based research team split 42 healthy older men (aged 65+) to take either 250 mg of NMN or a placebo daily for 12 weeks. 

The men taking NMN had significant increases in blood NMN and NAD+ levels, in addition to several NAD+-related metabolites. This indicates that NMN is effective for raising internal NAD+ levels. The NMN group also had significant improvements in gait speed and grip test with the left hand, indicating partial improvement of muscle strength and performance. Gait speed and grip strength are both known clinical markers of aging, as they are strong predictors of age-related muscle loss. However, there were no changes to skeletal muscle mass, which the authors suggest may be because of the relatively short study duration. 

The research team also measured lower extremity muscle strength with the 30-second chair-stand test, which counts how many times someone can go from sitting in a chair to standing (without using their arms) within a half-minute period. In this study, the men in the NMN group significantly increased their sit-to-stand times from baseline to the sixth week of the study, indicating improved leg strength. 

Lastly, there was a trend toward improvements in hearing ability in the right ear, and Igarashi and colleagues suspect that an enzyme in the sirtuin family may be involved in this enhancement. Sirtuins are so-called “longevity genes” that are dependent on NAD+ and play a role in maintaining healthspan and lifespan. Specifically, the sirtuin SIRT3 is thought to be involved with supporting hearing capabilities, as it protects hair cells in the ear and mediates age-related oxidative stress from harmful reactive oxygen species.

Better, Faster, Stronger With NMN

Although this study was relatively small and had a non-diverse sample of only healthy older Japanese men, the results are promising for using supplemental NMN to support muscle health with age. Future research should employ longer study periods or higher doses of NMN to see if more NMN increases skeletal muscle mass.

As a loss of muscular function impacts not only overall health and mortality but also independence and quality of life, maintaining strength as we grow older should be at the top of the aging population’s mind—and supporting NAD+ levels with NMN may be one way to do so.

The authors conclude in their paper, “​​In this study, we reported that the chronic oral supplementation of 250 mg of NMN per day is safe and a well-tolerated and effective strategy for boosting NAD+ metabolism in healthy older men. In addition, our exploratory analyses of the effects of NMN supplementation on physiological functions suggest NMN improves muscle strength, which is an important clinical indicator of aging.”

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References: 

Das A, Huang GX, Bonkowski MS, et al. Impairment of an Endothelial NAD+-H2S Signaling Network Is a Reversible Cause of Vascular Aging. Cell. 2018;173(1):74-89.e20. doi:10.1016/j.cell.2018.02.008

Igarashi M, Nakagawa-Nagahama Y, Miura M, et al. Chronic nicotinamide mononucleotide supplementation elevates blood nicotinamide adenine dinucleotide levels and alters muscle function in healthy older men. NPJ Aging. 2022;8(1):5. Published 2022 May 1. doi:10.1038/s41514-022-00084-z

Kim M, Seol J, Sato T, Fukamizu Y, Sakurai T, Okura T. Effect of 12-Week Intake of Nicotinamide Mononucleotide on Sleep Quality, Fatigue, and Physical Performance in Older Japanese Adults: A Randomized, Double-Blind Placebo-Controlled Study. Nutrients. 2022;14(4):755. Published 2022 Feb 11. doi:10.3390/nu14040755

Liao B, Zhao Y, Wang D, Zhang X, Hao X, Hu M. Nicotinamide mononucleotide supplementation enhances aerobic capacity in amateur runners: a randomized, double-blind study. J Int Soc Sports Nutr. 2021;18(1):54. Published 2021 Jul 8. doi:10.1186/s12970-021-00442-4