What is NAD+ and why is it important?
The human body stays healthy and strong by metabolizing nutrients into energy. This process is what keeps cells working at peak performance, and therefore what keeps the human body working at its peak performance. NAD+ is a critical compound in driving this process. Because of the important role this chemical plays in bodily metabolism, it is essential that you sustain healthy levels of it throughout your life. This can be a challenge in older adults because the aging process also correlates with a drop-off in the body’s natural ability to produce the compound from its constituent precursors. What is NAD+ exactly? Why is it so important? Where does it come from? And how can you supplement your body’s supply of it?
What is NAD+ and why is it important?
Nicotinamide adenine dinucleotide, or NAD, is an essential cellular coenzyme in all living things. It is made up of two nucleotides that, when combined, help drive each cell’s metabolic processes, including energy production and mitochondrial repair. In short, NAD is a helper molecule that binds to other enzymes in order to produce the reactions that make it possible for the other proteins inside a cell to carry out their proper functions. Poly-ADP-ribose polymerases and sirtuins are the two cellular proteins that require NAD in order to function; without its presence in a cell, the proteins will simply stop working.
Where does NAD come from?
When humans consume foods, the amino acids that those foods contain are broken down and provide the body’s cells with a supply of the precursors, such as nicotinic acid (NA), nicotinamide ribose (NR), and nicotinamide (Nam), that follow separate pathways to form into the compound NAD. NA, NR, and Nam are all versions of vitamin B3, a nutrient that our body gets from processing foods such as beef, eggs, leafy greens, milk, and yeast. Another NAD precursor is tryptophan, which is not a B3 vitamin. Of all of these, NR is the most efficient precursor for the production of NAD, since it has the most direct and effective pathway, known as the unlimited Salvage Pathway, but all three contribute to the NAD levels that your body needs to stay healthy. Tryptophan is the least effective since it has the most complex pathway, known as the De Novo Pathway, which converts it to quinolinic acid.
How do NAD levels in the body’s cells change as we age?
NAD is a finite resource, though: as the body ages, it becomes less efficient at processing those precursors into NAD and the levels of NAD inside the cells gradually shrink. This contributes to the decreasing efficacy of cellular functioning and a slowing of cell proteins metabolization of the energy they need. Between the ages of 40 and 60, the NAD levels in a typical adult drop by up to 50 percent. When you are born, your body carries approximately 10 nanograms of NAD per milligram of protein, but at the age of 40 those levels are close to 2.5 nanograms per milligram of protein.
These declines can be mapped across individual cell types as well. For example, the human brain contains, on average, 0.325 micromoles per gram of NAD at age 20; by 60, the amount has typically dropped to about 0.275 micromoles per gram. And other lifestyle variables that produce physiological stress can also decrease the body’s NAD levels, such as overeating or drinking too much alcohol. This drop-off in NAD levels is one of the leading contributors to our body’s slowing down as we age and many of the resultant medical conditions: when our cells have less energy, they become less active, effective, and reliable.
How can the body’s supply of NAD be supplemented?
Eating a diet rich in the different forms of vitamin B3 can help replenish some of your cells’ NAD supply, but this becomes less effective as the body ages. (No clear evidence yet indicates that other factors, like exercise, can boost NAD levels.) One of the easiest ways to continue to supply the body’s cells with the NAD they need to thrive and function is to take a daily dietary supplement containing key NAD precursors, such as GeroNAD+. A 2017 study found that taking a clinically validated 300 milligram dose of a precursor like GeroNAD+ can, after just eight weeks, increase NAD levels in the cells by an average of 40 to 50 percent. A NAD supplement replenishes the levels of the compound in your cells, promoting cellular repair, helping mitochondria stay healthy, and giving your cells the energy they, and you, need. These supplements work by delivering precursors rather than NAD itself because the NAD compound cannot survive the digestive process intact.
How did scientists learn about NAD?
In 1906, scientists William John Young and Sir Arthur Harden were examining the process of fermentation to understand how yeast is able to metabolize sugar into alcohol and carbon dioxide. Their study led them to discover the NAD compound, a finding of such important that it led Harden, along with fellow fermentation scientist Hans von Euler-Chelpin, to win the Nobel Prize in Chemistry in 1929.
Their work on NAD was further advanced by Otto Heinrich Warburg in the 1930s, who showed that the compound had an even more widespread metabolic function in living cells, beyond just fermentation. And in 1931, chemists C. K. Koehn and Conrad A. Elvehjem found that the NAD precursor nicotinic acid, a form of the vitamin B3, is a mitigator for the fatal disease pellagra—a discovery that eventually led to the practice of fortifying rice, flour, and other grains. In the 1940s and 1950s, scientists such as Jack Preiss, Nobel Prize-winner Arthur Kornberg, and National Medal of Science-winner Philip Handler expanded on this work. Kornberg’s experiments uncovered the enzyme that makes NAD, known as NAD synthetase, and Preiss and Handler determined how nicotinic acid becomes NAD.
The 1960s was a period that transformed scientists’ understanding of NAD, largely through the work of French scientist Pierre Chambon. Through experiments with nuclear extracts from chicken cells, Chambon was able to identify the Poly ADP-ribosylation process, in which NAD breaks down into nicotinamide and ADP-ribose. Then, in the 1990s, MIT biologists found that NAD was also responsible for activating the sirtuin protein in cells, which is responsible for regulating the cell’s homeostasis or internal equilibrium. Finally, in 2004 NR was isolated as the most efficient of the NAD precursors, allowing for the development of NAD dietary supplements, including GeroNAD+.