Nicotinamide mononucleotide is a biomolecule that naturally occurs in all living organisms. It consists of a ribo-nucleoside attached to a phosphate group. This molecule is a basic structural unit of RNA. NMN is considered crucial to increase the NAD⁺ levels in the body because it is a direct precursor of NAD⁺.
While we know that NAD-nicotinamide adenine dinucleotide is a critically used coenzyme in normal functioning of cells, it is essential to study how it is synthesized normally from its precursors. The main building blocks used for synthesis of NAD are tryptophan (an amino acid), nicotinamide (Nam), nicotinic acid (NA) also called niacin, nicotinamide riboside (NR) and NMN. All of these molecules are interestingly different forms of vitamin B3.There are many pathways to produce NAD⁺ in our body. Focusing on NMN, it is made from B vitamins in the body by attaching them to sugar phosphate by the enzyme, NAMPT. Another process is based on NR phosphorylation which also results in the formation of NMN.However, the one with the help of NAMPT is the most crucial step in maintaining the level of NAD⁺ as it is a rate limiting step. This essentially means that if the concentration of NAMPT is low, it can cause decreased levels of NMN which ultimately results in lower levels of NAD⁺. The levels of NAD⁺ are naturally maintained by calorie restriction as such a state increases the concentration of NAD⁺ in the cells. It is observed that CR state does not increase considerable concentration of NAD⁺ inside the cells. In this case, NMN or NAD supplements help a significant deal to retain the balance.
There are different reasons for the drain of NAD⁺ on a cellular level. The major contributing factor of them is the repair process of the damaged DNA. As we age, the metabolic stress increases as a result of which the chromosomes become unstable. To maintain them in an optimized state some special enzymes like sirtuins make use of NAD⁺ as a coenzyme on a large scale. This causes depletion of NAD⁺ in the body.In another important cell organelle- mitochondria, NAD⁺ are used in vital energy generation pathways. That is the reason it is critical to maintain the levels of NAD⁺ in the body.The importance of NMN is that it is more readily absorbed in the body than the NAD itself. This maintains the bioavailability of NMN to be converted into NAD⁺ as the need comes. In the end, the presence of NMN is helpful to optimize cellular functions which happen to slow down aging as well as those which prevent the age-related maladies in the long run. Those include diabetes, cancer, neurodegeneration and other immune conditions. Gerontologists are focusing on this wonder molecule as a potential anti aging drug.