• Dr Sajad Zalzala

What is NAD+ and NADH?

If you recall the Krebs Cycle from high school science class, you may remember one of its key components: NAD. What you may have missed (especially if it has been some time since high school) is the importance of NAD as we age. In fact, many do not recall nor realize the importance of NAD in so many functions of the human body until much later in life.

As you read on to learn the basics of the NAD and NADH definition, keep in mind the following three points:

  1. NAD refers to both NAD+ and NADH

  2. NAD is important in energy production and powers your longevity genes

  3. NAD levels naturally decrease as you age—but there are resources to help!

What is NAD+

NAD stands for nicotinamide adenine dinucleotide and is often referred to as NAD or NAD+. Simply stated, NAD is a vital coenzyme naturally produced by the body and found in every single cell. NAD+ is involved in hundreds of metabolic processes—the most important of which is cellular repair. NAD levels decline with age, as well as when the body undergoes metabolic stress, such as upon exposure to a virus.

Specifically, NAD comes in two forms: NAD+ and NADH. These two forms are chemically very similar, but they are not exactly the same. Sometimes, NAD Plus or NAD+ is referred to as just NAD (as above) but that plus sign is actually quite important as NAD really refers to the two forms as a collective.

Below, we break down the differences between NAD+ and NADH, as well as detail how the two forms work together in our bodies.

What NAD+ Does

NAD has two general sets of reactions in the human body. First, NAD+ helps to convert the nutrients we ingest into energy, which is then utilized in cellular metabolism. Secondly, NAD works as a molecule to help proteins regulate other cellular functions.

What is NADH

The NADH definition is as follows: nicotinamide adenine dinucleotide (NAD) + hydrogen (H)

How does this compare to NAD+? Simply put, NAD+ and NADH exist as what is termed a “redox couple.” NAD+ is the oxidized version and NADH is the reduced version.


In the body, NAD+ and NADH do different things. In the medical field, the jury is still out as to whether the ratio of NAD+ to NADH is more important or, on the flip side, if the amount of NAD+ is what we should be focusing on.

As research tests the above, here’s what we do know:

Our bodies have a limited supply of NAD+ that dwindles with age. As stated, NAD+ is fundamental for many biological processes to occur, and NAD+ is also necessary in order for sirtuins—a group of proteins—to ensure our metabolism stays healthy and cells can produce energy.

We also know that the ratio of NAD+ to NADH is what dictates whether our cells can effectively produce ATP or adenosine triphosphate. ATP is commonly referred to as the “energy currency” of the cell. When NAD+ is converted—or reduced—to NADH, ATP is created. This occurs in both the glycolysis and infamous Krebs cycles we learned in high school science class.

At the same time ATP is created, NADH is being oxidized within the electron transport chain to NAD+. As NADH loses its H+ electron, that H+ is utilized to fuel the mitochondria of the cell, creating more ATP. While all three processes—glycolysis, the Kreb’s cycle, and the electron transport chain—create ATP, the majority of ATP is created in the electron transport chain.

Because of the way in which the NAD+ and NADH molecules are utilized within these cycles in the body, and as NAD+ naturally declines as we age, our ratio is pushed even further into decline because NADH actually increases! Eventually, we develop an imbalance in our NAD+ to NADH ratio. In turn, that resulting imbalance ratio affects how well our cells are actually able to utilize the NAD+ we do have left.

As more research is completed, the importance of keeping the NAD+ to NADH ratio in balance will become even more clear—but, for now, we do know that increasing the amount of NAD+ available in our bodies is incredibly important when it comes to slowing the process of aging and age-related diseases.

In future blog posts, we will provide helpful information and opinions on the best NAD+ and NADH supplements to further fuel your longevity. We will also discuss the various ways you can boost NAD+ levels (such as with NAD+ Patches, NMN supplements, and nadh supplements) and the pros and cons of each.

Stay tuned!

Dr. Z


If you are interested in a prescription product, AgelessRx will assist in setting up a visit for you with a licensed physician, who will evaluate whether or not you are an appropriate candidate for the prescription product. If appropriate, may write you a prescription for the product which you can fill at the pharmacy of your choice.