Treating human cells with NMN triples NAD+ levels and increases the activity of AMPK — an enzyme that turns on sugar and fat metabolism in response to low energy.
Increasing nicotinamide adenine dinucleotide (NAD+) levels has promising anti-aging capabilities due to its fundamental role in cellular health. Likewise, AMPK, which is usually activated in response to low energy levels (including caloric restriction) is a fundamental molecule that promotes processes associated with longevity. Research has shown that taking the supplement nicotinamide mononucleotide (NMN) nearly doubles NAD+ in humans. Improvements in metabolic parameters like insulin sensitivity in prediabetic women and muscle oxygen utilization in long-distance runners have also been correlated with increasing NAD+ levels. Yet, dissecting a more precise cellular mechanism by which increasing NAD+ levels confer these benefits has yet to be done.
Published in the Journal of Biomedical Research and Environmental Sciences, Yamamoto and colleagues from Wellness-One Co., Ltd in Japan demonstrate that treating human MCF-7 breast cancer cells with 1 mg/mL NMN in culture raises AMP-activated protein kinase (AMPK) activity over 1,200%. What’s more, NMN treatment raised intracellular NAD+ levels three-fold. These findings suggest that by increasing NAD+ levels, NMN could boost the longevity-associated processes activated by AMPK, including enhanced mitochondrial health and autophagy — the cellular debris disposal system. This study also provides more evidence that supplementing with NAD+ precursors like NMN may drive cell energy production to alleviate faltering energy levels during aging.
To test the effects of administering NMN on AMPK activity, Yamamoto and colleagues treated MCF-7 human breast cancer cells with 1 mg/kg in culture and measured AMPK activity. Over the course of 24 hours, the researchers found that AMPK activity increased an astounding 1230.5% after one hour, 506.5% after 12 hours, and 849.2% after 24 hours compared to cells without treatment. These findings suggest that NMN treatment has a profound effect on amplifying AMPK activity, suggesting the promotion of processes like mitochondrial production and autophagy, both shown to have anti-aging effects.
AMPK has recently garnered substantial attention in aging research. For example, AMPK has been found to regulate cellular energy balance, protect mitochondrial function, and facilitate a cell debris-cleaning process called autophagy. Perhaps most interestingly, by enhancing mitochondrial function, AMPK acts as a molecular energy switch for the production of the cell energy molecule adenosine triphosphate (ATP) when ATP levels fall. Faltering AMPK activity with age has been linked to reduced energy levels in older adults. Therefore, increasing AMPK activity could mitigate age-related disease and promote longevity.
Yamamoto and colleagues tested the effects of treating cancer cells with NMN on intracellular NAD+ levels. The research team found that NMN more than tripled NAD+ levels within the MCF-7 cells. These results recapitulate previous findings showing that NMN effectively boosts NAD+ levels by substantial amounts in human cells.
By enhancing the activity of the cell energy-regulating AMPK, NMN may promote cellular rejuvenation as breast cancer cells age. Possibly the biggest issue with the study, though, was that Yamamoto and colleagues used the MCF-7 breast cancer cell lineage that may have already had low AMPK activation and faltering NAD+ levels. There are numerous alternative cell lines that do not come from diseased tissues like breast cancer that Yamamoto and colleagues could have used, such as vascular cells (endothelial cells). The use of the breast cancer cells may be seen as a major limitation of the study since little is known about how diseased tissue like cancer affects AMPK activity and NAD+ levels.
Analyzing NMN’s Impact on Blood ATP Levels in HumansFuture studies examining the efficacy of NMN against aging could look at blood plasma ATP levels to find out whether taking NMN boosts cell energy. The recommended dose of NMN lies somewhere between 250 mg to 500 mg per day, so a dose-dependency analysis could test the effects of different daily doses of NMN. This experiment could span over the course of a few months to find out whether NMN not only potentially boosts AMPK activity and NAD+ levels but also results in higher ATP production.