NAD+ Precursor
NAD+ precursors are molecules that can be converted into NAD+, a vital coenzyme found in all living cells, crucial for energy production, cellular repair, and longevity. Taking NAD+ directly is generally considered inefficient due to its inability to enter cells directly due to its large size and polar nature, making it unable to cross the cell membrane effectively. Thus, NAD+ precursors like NMN, NR, and NA, which are smaller and can enter cells more easily, are used to increase cellular NAD+ levels, as they can be converted into NAD+ once inside the cells. These precursors are therefore preferred for supplementation to boost NAD+ levels efficiently within the body.
| Precursor | Nicotinamide Mononucleotide (NMN) | Nicotinamide Riboside (NR) | Nicotinamide (NAM) | Nicotinic Acid (NA) |
|---|---|---|---|---|
| Description | A vital NAD+ precursor involved in the biosynthesis of NAD+. NMN enters cells via specific transporters. | A significant precursor that is converted into NMN before participating in NAD+ synthesis. NR can enter cells through unique transporters. | A form of vitamin B3 and a precursor of NAD+, contributing to its synthesis through the salvage pathway. | Another form of vitamin B3 serving as a precursor of NAD+. |
| Pathway | N/A | N/A | Salvage Pathway | Preiss-Handler Pathway |
| Conversion Process | Converted directly to NAD+ through a series of enzymatic reactions. | Phosphorylated to NMN by the enzyme NR kinase, then converted to NAD+. | Converted to NMN by the enzyme nicotinamide phosphoribosyltransferase (NAMPT), then to NAD+. | Converted to NAD+ via a series of enzymatic reactions: NA → NAMN → NAAD → NAD+. |