NMN increases NAD+ (nicotinamide adenine dinucleotide) levels through specific biochemical pathways. Here's a detailed explanation of how NMN achieves this:
Endogenous Synthesis Pathway
Within cells, NMN can be synthesized endogenously, primarily through a cycle involving nicotinamide (NAM). This pathway starts with NAM, which is converted into NMN by enzymes like nicotinamide phosphoribosyltransferase (NAMPT), a key enzyme in this process. Subsequently, NMN is further converted into NAD+. NAD+ can also be broken down back into NAM, maintaining a balance of NAD+ withi
n the cell.
Exogenous NMN Intake
When exogenous NMN is ingested, it enters cells and participates in the biosynthesis of NAD+ through two main pathways:
NR-NRKs Pathway: Nicotinamide riboside (NR) can be converted into NMN by nicotinamide riboside kinases (NRKs) after entering the cell.
SLC12A8 Transporter Pathway: NMN can directly enter cells via the SLC12A8 transporter.
Role of Enzymes
NMNAT: Nicotinamide mononucleotide adenylyltransferase (NMNAT) enzymes catalyze the final step in the synthesis of NAD+ from NMN.
CD73 and ENTs: In the case of reduced nicotinamide mononucleotide (NMNH), the reduced form of NMN, it can be converted into nicotinamide riboside hydride (NRH) by CD73 dephosphorylation and then enter cells through ENTs to synthesize NADH, although it's unclear if NMNH can be directly transported into cells.
Clinical Evidence
Clinical studies, such as one conducted by researchers at Toyama University in Japan, have shown that daily ingestion of 250 milligrams of NMN significantly increases blood NAD+ levels. Over a 12-week period, participants who took NMN orally showed almost a doubling of their blood NAD+ levels, with no adverse effects on blood lipids, white blood cell counts, liver function markers, body weight, or blood pressure.
Functions of Elevated NAD+ Levels
By increasing NAD+ levels, NMN supports various physiological functions, including:
Enhancing energy production by supporting the production of ATP.
Improving insulin sensitivity and reversing mitochondrial dysfunction, which may contribute to anti-aging effects.
Enhancing DNA repair mechanisms and maintaining genomic stability.
Potentially improving conditions such as Alzheimer's disease and Parkinson's disease by enhancing memory and cell viability in rat models.
In conclusion, NMN increases NAD+ levels through both endogenous synthesis pathways within cells and exogenous intake, with the involvement of key enzymes and clinical evidence supporting its effectiveness in elevating blood NAD+ levels. These elevated NAD+ levels, in turn, support various physiological functions and may have potential benefits for health and longevity.
