Nicotinamide adenine dinucleotide (NAD+) is made inside living cells through several linked biosynthesis routes that convert vitamin precursors and amino acids into the active coenzyme. The body uses three primary pathways to do this: the de novo pathway, the Preiss-Handler pathway, and the salvage pathway. Each route starts from a different raw material, which means cells can keep a steady NAD+ supply even when one source runs low. This article explains where NAD+ comes from, both inside the cell and from the diet, and how laboratory precursors such as nicotinamide riboside and NMN are synthesized for research.
Key Takeaways
- NAD+ is built from two nucleotides, one carrying an adenine base and one carrying nicotinamide, joined through their phosphate groups.
- Three pathways make it: de novo (from tryptophan), Preiss-Handler (from nicotinic acid), and salvage (recycling nicotinamide).
- The salvage pathway is the most used route, with the enzyme NAMPT catalysing the rate-limiting step.
- The liver is the central hub, but every cell with mitochondria can make its own NAD+.
- Dietary niacin, nicotinamide and tryptophan supply the raw materials; NAD+ levels decline with age as NAMPT activity falls.
What NAD+ Is Made From in the Body
NAD+ is a dinucleotide, meaning it is assembled from two nucleotides joined by their phosphate groups. One half contains an adenosine diphosphate base; the other contains nicotinamide attached to ribose sugars. The building blocks come from an amino acid (tryptophan) and from B3 vitamins (nicotinic acid and nicotinamide). Because the molecule is constantly consumed and rebuilt, the body treats these components as a recyclable pool rather than a fixed store, which keeps energy metabolism and DNA-repair enzymes supplied around the clock.
The Three Biosynthesis Pathways That Make NAD+
Research on NAD+ metabolism describes three dedicated routes that feed into the same final coenzyme:
- The de novo pathway: converts the amino acid tryptophan into NAD+ through the multi-step kynurenine pathway, passing through quinolinic acid before reaching the finished molecule. This route operates mainly in the liver.
- The Preiss-Handler pathway: starts from nicotinic acid (a form of niacin) and converts it through intermediates such as nicotinic acid mononucleotide (NAMN) and nicotinic acid adenine dinucleotide (NAAD) before a final amidation step yields NAD+.
- The salvage pathway: the most efficient and most frequently used source. It recaptures nicotinamide released when NAD+ consuming enzymes break the molecule down, then regenerates fresh NAD+.
How NAD+ Is Made From Vitamin B3 and Niacin
Vitamin B3 is the umbrella term for nicotinic acid and nicotinamide, the two forms that feed NAD+ synthesis most directly. Nicotinic acid enters the Preiss-Handler pathway, where it is converted to NAMN, then to NAAD, and finally amidated into NAD+. This is why niacin-rich foods are so closely tied to the body's capacity to build the coenzyme. The metabolism of NAD+ depends on a reliable intake of these precursors to keep the pathway running.
How NAD+ Is Made From Nicotinamide
Nicotinamide is both a dietary source and the main by-product of NAD+ consuming enzymes such as sirtuins and PARPs. In the salvage pathway it is converted to nicotinamide mononucleotide (NMN) by the enzyme NAMPT, the rate-limiting step of the whole route. NMN is then adenylated by NMNAT enzymes to regenerate NAD+. This recycling loop is why the salvage pathway is the dominant day-to-day source of the coenzyme.
How NAD+ Is Made From Tryptophan
When dietary niacin is scarce, the body can build NAD+ from scratch using the essential amino acid tryptophan. Tryptophan is first converted to N-formylkynurenine and travels down the kynurenine pathway through roughly eight enzymatic steps to form quinolinic acid, which is then converted toward the finished coenzyme. Protein-rich foods are the foundational substrate for this de novo route.
Where NAD+ Is Made Inside the Body
NAD+ production is localised to match each tissue's energy demands rather than being centralised in one organ:
- The liver is the primary hub for systemic biosynthesis, processing dietary precursors and distributing them to other tissues.
- Every cell with mitochondria can produce its own supply to fuel the electron transport chain.
- High-energy tissues such as the heart, brain and skeletal muscle show significant localised synthesis.
- Within the cell, synthesis takes place across several compartments: the cytoplasm (supporting glycolysis), the mitochondrial matrix (supporting the citric-acid cycle), and the nucleus (supplying DNA-repair enzymes).
Where NAD+ Comes From in Energy Metabolism
Beyond being synthesized, NAD+ is continuously regenerated during the reactions that release energy from food. Understanding these steps answers the common question of where the oxidised form keeps coming from:
- Glycolysis: NAD+ acts as an electron acceptor, becoming NADH as glucose is broken down to pyruvate.
- Pyruvate oxidation: pyruvate entering the mitochondria reduces more NAD+ to NADH as it is converted to acetyl-CoA.
- The Krebs (citric-acid) cycle: several steps strip electrons onto NAD+, generating NADH that carries them onward.
- Cellular respiration: at Complex I of the electron transport chain, NADH is re-oxidised back to NAD+, restoring the pool so the earlier steps can keep running.
This redox cycling means the same molecules of NAD+ are used, spent and restored thousands of times, which is why the balance between biosynthesis and consumption matters as much as the total amount made.
Natural and Dietary Sources of NAD+
The body relies on nutrition to supply the precursors it cannot invent from nothing. Niacin-rich foods are the main dietary route: poultry, beef and fish are strong sources of nicotinamide, while brown rice and whole grains provide nicotinic acid. Dairy products and cow's milk carry trace amounts of precursors. Plant foods such as broccoli, cabbage, avocado and edamame contain small amounts of NMN precursors. The gut microbiome also contributes, as certain bacteria synthesize B-vitamins and precursors that add to the systemic NAD+ pool.
How Aging and Lifestyle Affect NAD+ Production
NAD+ synthesis is not constant across a lifespan. As people age, NAMPT activity tends to fall while consumption rises, so the salvage pathway recycles less efficiently and total levels drift down. This decline is a well-documented feature of the ageing process. Lifestyle inputs push in the other direction: a nutrient-dense diet supplies B3 vitamins and amino acids, and exercise such as high-intensity interval training stimulates NAMPT expression and mitochondrial biogenesis, both of which support the machinery that makes NAD+.
How NAD+ Precursors and Research Compounds Are Made
In research and clinical-nutrition settings, scientists use chemically synthesized precursors designed to bypass metabolic bottlenecks in the pathways above. The most prominent are nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN), both intermediates that can prime the salvage pathway directly. These are manufactured as defined-purity compounds for laboratory study. At Peptides Please, all products, including our NAD+ research material, are supplied strictly for research use only and are not for human or animal use.
Researchers sourcing study-grade material can review the full NAD+ research range or go straight to the NAD+ 500mg vial. For related reading, see our guides on the difference between NAD+ and NADH and NAD+ in food sources.
Frequently Asked Questions
What is NAD+ made from?
NAD+ is made from two nucleotides, one carrying an adenine base and one carrying nicotinamide, joined by their phosphate groups. The raw materials come from the amino acid tryptophan and from the B3 vitamins nicotinic acid and nicotinamide.
What are the three pathways that make NAD+?
The de novo pathway builds NAD+ from tryptophan, the Preiss-Handler pathway builds it from nicotinic acid, and the salvage pathway recycles nicotinamide back into the coenzyme. The salvage route is the most frequently used.
Does the body produce its own NAD+?
Yes. Every cell with mitochondria can synthesize NAD+, and the liver acts as the central hub that processes dietary precursors and distributes them to other tissues.
Which enzyme controls how much NAD+ is made?
NAMPT catalyses the rate-limiting step of the salvage pathway, converting nicotinamide to NMN. Because the salvage pathway is the dominant source, NAMPT activity strongly influences overall NAD+ output, and it tends to decline with age.
How are NAD+ precursors made for research?
Precursors such as nicotinamide riboside and NMN are chemically synthesized as defined-purity compounds in certified facilities and verified by third-party testing. They are intended for laboratory research only, not for human or animal use.
Source Research-Grade NAD+ at Peptides Please
Peptides Please supplies research-grade compounds at high purity, verified by independent third-party laboratory testing, with shipping across the USA and Canada. Explore the NAD+ research collection to order study material for your work.
