What Are NAD+ Supplements Made Of? The Science of Precursors

December 3, 2025 •

4 min read

According to scientific research, the large NAD+ molecule cannot be effectively absorbed directly when taken orally, making direct supplementation ineffective. This is why what are NAD+ supplements made of are precursor compounds, such as various forms of vitamin B3, which the body can efficiently convert into NAD+.

Quick Summary

NAD+ supplements utilize precursor molecules, predominantly forms of vitamin B3 like nicotinamide mononucleotide (NMN), nicotinamide riboside (NR), nicotinamide, and niacin, to increase cellular NAD+ levels. Because NAD+ itself is poorly absorbed orally, these smaller compounds serve as building blocks for the body's natural synthesis pathways.

Key Points

Precursors, Not NAD+: NAD+ supplements are made of precursor molecules, primarily forms of vitamin B3, because the NAD+ molecule itself is too large for effective oral absorption.
Two Primary Ingredients: Nicotinamide Riboside (NR) and Nicotinamide Mononucleotide (NMN) are the two most common and efficient precursors used to raise cellular NAD+ levels.
Forms of Vitamin B3: Other vitamin B3 variants like nicotinamide (NAM) and niacin (NA) also function as NAD+ precursors but have different metabolic pathways and potential side effects, such as flushing with niacin.
Supporting Compounds: Many supplements include additional ingredients like resveratrol or pterostilbene to further support cellular functions and activate sirtuins.
Multiple Synthesis Pathways: The body can create NAD+ from various precursors using several metabolic routes, including the highly efficient salvage pathway used by NR and NMN.

Understanding the Core Ingredients

Most NAD+ supplements do not contain the NAD+ molecule itself. Instead, they provide the raw materials or "precursors" that the body uses to synthesize NAD+ through a process called the salvage pathway. These precursors are all related to vitamin B3 and include Nicotinamide Riboside (NR), Nicotinamide Mononucleotide (NMN), nicotinamide (NAM), and niacin (nicotinic acid or NA).

Nicotinamide Riboside (NR)

Nicotinamide Riboside (NR), frequently marketed under brand names like Niagen®, is a highly popular and well-researched NAD+ precursor. As a form of vitamin B3, NR is efficiently absorbed and converted into NMN by enzymes called nicotinamide riboside kinases (NRKs) before finally becoming NAD+. A key advantage of NR over some other forms of vitamin B3 is that it does not cause the uncomfortable flushing sensation. Its small size allows for broader cellular uptake, and numerous human trials have confirmed its ability to boost NAD+ levels safely and effectively.

Nicotinamide Mononucleotide (NMN)

Nicotinamide Mononucleotide (NMN) is another direct and potent precursor that sits one step closer to NAD+ in the salvage pathway than NR. The conversion of NMN to NAD+ is catalyzed by the NMN adenylyltransferase (NMNAT) enzyme. Historically, some believed NMN was too large to enter cells directly, but the discovery of a specific transporter (Slc12a8) has provided a clearer picture of its efficient cellular uptake. Several clinical studies have also shown NMN to be effective at raising NAD+ levels.

Other Precursors from the Vitamin B3 Family

While NR and NMN are the most prominent, other forms of vitamin B3 are also used as NAD+ precursors:

Nicotinamide (NAM): Also known as niacinamide, this is the most abundant form of vitamin B3 in the salvage pathway. It does not cause flushing. However, research suggests that high doses of NAM can inhibit sirtuin enzymes, which are important for cellular health and require NAD+ to function.
Niacin (Nicotinic Acid or NA): This traditional form of vitamin B3 follows a different pathway called the Preiss-Handler pathway. While effective, it commonly causes a skin flushing effect at high doses, making it less popular for NAD+ boosting.

The Role of Tryptophan

The body can also synthesize NAD+ from the amino acid tryptophan, which is found in protein-rich foods. This is known as the de novo pathway and is far less efficient than the salvage pathway precursors like NR and NMN. It requires multiple enzymatic steps, and a significant amount of tryptophan is needed to produce the same amount of NAD+ as a small dose of vitamin B3. For this reason, supplements do not typically rely on tryptophan to boost NAD+.

Comparison of Major NAD+ Precursors


Feature	Nicotinamide Mononucleotide (NMN)	Nicotinamide Riboside (NR)	Nicotinamide (NAM)	Niacin (NA)
Molecular Structure	Contains a phosphate group, making it slightly larger than NR.	Consists of nicotinamide and ribose, without the phosphate group.	Basic form of vitamin B3, simple structure.	Another basic form of vitamin B3, simple structure.
Absorption	Absorbed via a specific transporter (Slc12a8) and potentially via conversion to NR.	Readily absorbed by cells.	Absorbed via passive diffusion.	Absorbed and enters the Preiss-Handler pathway.
Side Effects	Generally well-tolerated with few side effects reported.	Well-tolerated with minimal side effects.	Does not cause flushing but may inhibit sirtuins at high doses.	Often causes uncomfortable skin flushing.
Pathway	Directly converted to NAD+ in one step via the salvage pathway.	Converted to NMN first, then to NAD+ via the salvage pathway.	Recycled back to NMN and then NAD+ via the salvage pathway.	Converted through the Preiss-Handler pathway in multiple steps.
Research Status	Extensive preclinical and growing human clinical data; some recent regulatory considerations impacting availability.	Significant body of research, including numerous human clinical trials.	Well-established but limited in direct NAD+ boosting studies compared to NR/NMN.	Long history, primarily used for cholesterol, with known side effects.

Accessory and Stabilizing Ingredients

Besides the main precursors, NAD+ supplements often contain other ingredients to enhance efficacy, stability, or absorption:

Polyphenols: Compounds like resveratrol, pterostilbene, bio-quercetin, and fisetin are sometimes added. These are believed to act as sirtuin activators, working synergistically with increased NAD+ levels to promote cellular health.
Magnesium: Magnesium is a cofactor for enzymes involved in the NAD+ synthesis pathway, so its inclusion can support efficient conversion.
Stabilizers and Fillers: To ensure shelf-stability and proper capsule formation, manufacturers use excipients. Examples include microcrystalline cellulose, vegetable magnesium stearate, and hydroxypropyl methylcellulose (for vegetarian capsules).

Why Use Precursors Instead of NAD+?

As previously mentioned, oral NAD+ supplements are not made of the NAD+ molecule itself because of its poor bioavailability. The molecule is too large to easily cross cellular membranes, requiring it to be broken down into smaller components for transport into the cell. These smaller, more stable precursors, like NR and NMN, are far more effective at entering cells, where the body can then convert them back into functional NAD+. This natural process leverages the body's existing cellular machinery to increase NAD+ levels efficiently.

Conclusion

In summary, NAD+ supplements rely on a variety of precursor molecules, predominantly different forms of vitamin B3, rather than the NAD+ molecule itself. The most common and direct precursors are Nicotinamide Mononucleotide (NMN) and Nicotinamide Riboside (NR), both of which are highly efficient building blocks for cellular NAD+ production. Other forms like nicotinamide and niacin are also utilized, though they have different pathways and potential side effects. Many supplements may also include accessory compounds like polyphenols to enhance their effect. Understanding the composition of these supplements allows consumers to make informed choices based on the science of how these key ingredients function to support cellular health.

Learn more about the complex metabolism of NAD+ and its precursors from this authoritative source from the National Institutes of Health.

Frequently Asked Questions

You cannot effectively supplement with NAD+ directly because it is a very large molecule that is poorly absorbed orally. The body must break it down into smaller precursor molecules to absorb and utilize it, which is why supplements provide these building blocks instead.

NMN and NR are both potent NAD+ precursors derived from vitamin B3. The main difference lies in their molecular structure—NMN has an extra phosphate group. NMN is the more direct precursor, requiring one less conversion step than NR to become NAD+ inside the cell.

No, while nicotinamide (niacinamide) and niacin (nicotinic acid) are also forms of vitamin B3 and NAD+ precursors, they are chemically distinct from NMN and NR. Niacin often causes flushing, and nicotinamide can inhibit sirtuins, issues not associated with NMN and NR.

Besides the main precursors, some supplements include complementary ingredients such as polyphenols (e.g., resveratrol, pterostilbene), magnesium, and other B vitamins. These are added to enhance absorption, stability, or provide synergistic benefits.

The body can synthesize NAD+ from the amino acid tryptophan, but this process is very inefficient and requires multiple steps. Precursor supplements like NMN and NR use the salvage pathway, which is a much more direct and efficient route to boosting NAD+ levels.

The main precursors, especially NR and NMN, have been studied in numerous human trials and are generally considered safe and well-tolerated. However, it's always recommended to consult a healthcare provider before starting any new dietary supplement.

Differences in cost can arise from the specific precursors used, ingredient purity, brand reputation, and the inclusion of other ingredients like polyphenols. NMN and NR, for instance, are generally more expensive to produce than traditional forms of vitamin B3.