The full name of NAD+ is nicotinamide adenine dinucleotide (oxidized state). Its main function is an enzyme that communicates between mitochondria and the nucleus. It can repair DNA and activate longevity genes. As age increases, the NAD+ content in the body will decrease significantly. Therefore, if the NAD+ content can be increased through external supplementation, it can play a so-called longevity role. However, NAD+ has a macromolecular structure and cannot break through the cell wall, so direct oral administration is ineffective. NAD+ precursors must be taken or injected to indirectly replenish NAD+ through metabolism.
In 2020, "Nature" magazine took stock of the world's most potential anti-aging substances, and NAD+ and its precursor substances were ranked in the first echelon. NAD+ has a total of five precursor substances, including nicotinic acid, tryptophan, nicotinamide, NR and β-Nicotinamide Mononucleotide (NMN). These substances can all be converted into NAD+ in terms of scientific theory. Among them, NMN is considered to be the best choice for NAD+ supplements.
Why is NMN the best choice for NAD+ supplements? Next, let us distinguish the advantages and disadvantages of the five major precursor substances through three major synthetic pathways.
Three major synthesis pathways:
1. Niacin/NA becomes NAD+ through the Preiss-Handler pathway.
2. Tryptophan/Trp enters the Preiss-Handler pathway through the de novo synthesis pathway and becomes NAD+.
3. Nicotinamide/NAM, nicotinamide mononucleotide/NMN, and nicotinamide ribose/NR become NAD+ through the salvage synthesis pathway.
The pathways for synthesizing NAD+ from tryptophan/Trp and nicotinic acid/NA are tortuous, and the content of synthesized NAD+ is less than 15% of the total;
Nicotinamide/NAM will inhibit the effects of SIRT (longevity gene) and PARP1 (DNA repair), and excessive accumulation of nicotinamide in the body is harmful;
As the precursor of NMN, NR needs to be phosphorylated by NPK1-2 and converted into NMN after entering the body, and then converted from NMN to NAD+. There are no NPK1 and NPK2 enzymes in mitochondria to convert NR into NMN, which means that NR is difficult to play a role in mitochondria.
Nicotinamide mononucleotide/NMN quickly converts NAD+, with a short path, high efficiency, and fast speed, so NMN has become the first choice of the five NAD+ precursors.
*Special note - This article is for informational purposes only and cannot replace a doctor's treatment diagnosis and advice. It should not be regarded as a recommendation or proof of efficacy of the medical products involved. If it involves disease diagnosis, treatment, and rehabilitation, please be sure to go to a professional medical institution to seek professional advice.