NAD+ comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-06-07. Where a claim depends on a specific study, the study is described rather than over-claimed.
In redox reactions, NAD+ accepts a hydride ion, which consists of two electrons and one proton. The hydride adds to the nicotinamide ring at a specific carbon, converting NAD+ into NADH. Dehydrogenase enzymes use this step in glycolysis, the citric acid cycle, and fatty acid oxidation. NADH later donates electrons to the mitochondrial electron transport chain, helping to drive ATP synthesis. The balance between NAD+ and NADH reflects the metabolic state of a cell, and shifts in that balance can alter how pathways operate.
Beyond electron transfer, NAD+ serves as a substrate for enzymes that cleave it and attach its ADP-ribose portion to other molecules. This group includes poly(ADP-ribose) polymerases, CD38, and sirtuins. Such reactions consume NAD+ and can influence its availability for metabolism. Cells replenish NAD+ through a salvage pathway that recycles nicotinamide and through routes starting from tryptophan or vitamin B3 forms. How these synthesis and consumption routes are coordinated across tissues remains an active area of study, and compartment-specific concentrations are difficult to measure directly.
NAD+ is commonly measured by high-performance liquid chromatography with ultraviolet detection, often at 254 or 260 nm. Enzymatic cycling assays provide higher sensitivity by coupling NAD+ to a reporter reaction. Mass spectrometry can distinguish NAD+ from close analogues and confirm isotope labeling. Sample preparation usually involves rapid quenching of metabolism to prevent interconversion with NADH. Because NAD+ and NADH differ by one hydride, extraction conditions strongly affect the measured ratio.
In aqueous solution, NAD+ is most stable under mildly acidic to neutral conditions and degrades faster at high pH or elevated temperature. The molecule can hydrolyze at the pyrophosphate bond or undergo nonenzymatic cyclization. Buffers, chelating agents, and cold temperatures slow these losses during analysis. Repeated freeze-thaw cycles are generally avoided because they can promote degradation and concentration changes. Light exposure is also controlled, though NAD+ is less photolabile than some related nucleotides.
Commercial NAD+ is supplied as a solid, often as the free acid or a salt, and purity is verified by chromatographic methods. Laboratories typically store it desiccated at minus 20 degrees Celsius or below. Working solutions are prepared fresh because even sterile aqueous solutions can lose activity over hours to days depending on pH and temperature. Documentation may include a certificate of analysis, an assay value, and a recommended retest date. Researchers should verify identity and purity when results depend on precise cofactor concentrations.
| Property | Value | Notes |
|---|---|---|
| Molar mass | 663.43 g/mol | For the free acid form; salts have higher mass. |
| Appearance | White to off-white powder | Often hygroscopic; may clump on exposure to air. |
| Solubility | Freely soluble in water | Poorly soluble in nonpolar organic solvents. |
| Typical storage | -20 °C, desiccated | Protect from light and moisture; avoid repeated freeze-thaw. |
| Common synonyms | beta-NAD, DPN | DPN stands for diphosphopyridine nucleotide, an older name. |
Purified NAD+ is typically supplied as a white to off-white powder and stored desiccated at low temperature. Airtight containers limit moisture uptake, while protection from light reduces degradation of the nicotinamide ring. Aqueous stock solutions are less stable than solid material and are often aliquoted before freezing. Repeated freeze-thaw cycles can lower integrity, so working portions are kept separate. Purity is commonly checked by ultraviolet absorbance near 260 nm, high-performance liquid chromatography, or mass spectrometry.
Stability studies show that NAD+ can hydrolyze under prolonged heat, extreme pH, or microbial contamination. Phosphate buffers near neutral pH are often used for short-term handling, though exact stability depends on concentration, temperature, and matrix. In biological samples, endogenous enzymes can rapidly degrade NAD+, making cold chain and fast processing important. Analytical reports should state extraction conditions, internal standards, and validation parameters. Without those details, comparisons across studies remain difficult and potentially misleading.
Laboratory measurement of NAD+ often begins with rapid quenching of cell or tissue samples to prevent enzymatic conversion. Acidic or alkaline extraction can precipitate proteins, but the chosen method affects recovery of oxidized and reduced forms. Enzymatic cycling assays provide high sensitivity by amplifying a NAD+-dependent reaction. High-performance liquid chromatography and mass spectrometry offer separation and structural confirmation. Each method has trade-offs in throughput, specificity, and the ability to distinguish NAD+ from close analogues.
Beyond redox chemistry, NAD+ serves as a substrate for enzymes that cleave the molecule and transfer its ADP-ribose moiety or remove acetyl groups. Sirtuins consume NAD+ during deacetylation, poly(ADP-ribose) polymerases use it in DNA damage responses, and CD38 enzymes hydrolyze it to signaling metabolites. These consumption pathways mean that NAD+ availability can influence gene regulation, DNA repair, and calcium signaling. Cellular NAD+ concentrations decline in some tissues with age in animal models, but whether this decline is a cause or consequence of aging in humans remains an active open question.
Nicotinamide adenine dinucleotide, commonly abbreviated NAD+, is a dinucleotide coenzyme built from an adenine nucleotide and a nicotinamide nucleotide joined by a pyrophosphate linkage. Its oxidized form carries a positive charge on the nicotinamide ring, while the reduced form, NADH, carries a hydride equivalent. The molecule participates in hundreds of oxidoreductase reactions, where it accepts or donates electrons and protons. Because it can cycle between oxidized and reduced states without net consumption, NAD+ functions as a reusable electron carrier rather than a fuel molecule.
In glycolysis, the tricarboxylic acid cycle, and fatty acid oxidation, NAD+ is reduced to NADH at specific dehydrogenase steps. NADH then delivers electrons to the mitochondrial electron transport chain, mainly at complex I, supporting oxidative phosphorylation and ATP production. The balance between NAD+ and NADH, often expressed as a ratio, influences metabolic flux and redox homeostasis in different cellular compartments. Cytosolic and mitochondrial pools are connected but not identical, and their ratios can differ substantially because of compartment-specific enzymes and transport systems.
A basic chestnut or "red" horse has a solid copper-reddish coat, with a mane and tail that is close to the same shade as the body coat. Sorrel is a term used by American stock horse registries to describe red horses with manes and tails the same shade or lighter than the body coat color. In these registries, chestnut describes the darker shades of red-based coats.
siRNAs can be incorporated into a RNA-induced transcriptional silencing (RITS) complex. An active RITS complex will trigger the formation of heterochromatin around DNA matching the siRNA, effectively silencing the genes in that region of the DNA.
=== Simple epithelium === Simple epithelium is a single layer of cells with every cell in direct contact with the basement membrane that separates it from the underlying connective tissue. In general, it is found where absorption and filtration occur. The thinness of the epithelial barrier facilitates these processes. In general, epithelial tissues are classified by the number of their layers and by the shape and function of the cells. The basic cell types are squamous, cuboidal, and columnar, classed by their shape.
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When the university partially reopened, Cremer was still temporarily banned from work due to her German citizenship and would secretly visit the university in a delivery truck to continue research. Cremer was allowed to return to her work in late 1945. Prior completed the research demonstrating a novel method for measurements and qualitative and quantitative analysis in 1947. Another student of Cremer's, Roland Müller wrote his dissertation on the analytical possibilities of the gas chromatograph. Cremer was appointed director of the Physical Chemistry Institute at Innsbruck and was made a professor in 1951. Cremer began presenting Prior and Müller's work in 1947 at various scientific meetings. In 1951, three papers on Cremer's work were published in Zeitschrift für Elektrochemie, a lesser known German scientific journal. The scientific community responded to presentations and papers either negatively or not at all. Many believed that older methods were sufficient. In 1952, the British Anthony Trafford James and Archer Porter Martin and in 1953, the Czech J. Janak published reports claiming the invention of gas chromatography. Martin and his partner Richard Laurence Millington Synge won the Nobel Prize for partition chromatography, which is often credited for introducing the use of gas as a mobile phase, in 1952. All were completely ignorant of Cremer's early work. This has been attributed to the fact that Cremer spoke to the wrong people in the wrong places. Austrian analytical and micro chemists did not focus on gases, so the idea did not gain interest.
== Collaborations == Saladino describes himself as an "adventure buddy" of another carnivore diet influencer, Anthony Gustin, founder of online food store Perfect Keto. The pair visited the Hadza people of Tanzania in 2022, promoting them as a dietary model; Saladino said "The Hadza are the closest thing we have to a time machine." According to science writer Dorsa Amir, "the idea that the 'correct' diet is an ancient one is also the backbone of fads like the paleo diet, [and] Saladino's carnivore diet." Saladino is the founder of Heart & Soil, an Austin, Texas-based company producing food supplements. Saladino co-owns it with fellow carnivore diet influencer Brian Johnson, known as Liver King. Heart & Soil sells bottles of encapsulated organ meat-based supplement products and liver pills. He collaborated with California luxury grocery store Erewhon in 2023 on the store's Raw Animal-Based Smoothie, which mixes kefir (fermented milk), along with other ingredients, with beef organs and "Immunomilk" (a product made of freeze-dried cow's colostrum). The raw milk was supplied by California-based Raw Farms, until it switched to pasteurization after tests of its milk turned up positive for H5N1 influenza A virus. Consuming raw animal meat poses a risk of bacterial infection.
== Awards and honours == 1936 Fellow of the Royal Society of Canada 1946 Order of the British Empire 1962 Honorary member of the Canadian Public Health Association (CPHA) 1964 Banting Medal of the American Diabetes Association 1967 Canada Gairdner International Award 1971 Honorary doctor of the University of Toronto 1971 Charles H. Best Prize
The report of this year-long inquiry, published in June 2004, found that the Mariam Appeal was undertaking charitable work (and so ought to have registered with the commission), but did not substantiate allegations that any funds had been misused. It emerged some years later that Galloway had appealed in a letter dated 24 April 2003 to Lord Goldsmith, the Attorney-General, to stop the investigation into the Mariam Appeal. According to a report in The Times, after the letter was released under the Freedom of Information Act, Galloway falsely asserted that the appeal "received no money from Iraq". A further Charity Commission Report published on 7 June 2007 found that the appeal had received funds from Fawaz Zureikat that originated from the Oil-for-Food Programme, and concluded that,
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The previous election in 2023 saw a shift towards progressive parties, with the Move Forward Party winning 151 seats followed by the Thaksin Shinawatra-aligned Pheu Thai Party. The governing coalition of conservative parties only won 15% of the seats, with the Bhumjaithai Party being the only one to increase their numbers. Move Forward initially formed an eight party coalition with Pheu Thai, Thai Sang Thai, Prachachat, Thai Liberal, New Social Power, Thai Ruam Palang and the Fair Party. The coalition had a total of 313 MPs, giving them a majority in the House of Representatives. However, under the transitory provisions of the 2017 constitution, the prime minister was to be chosen by both elected MPs and NCPO-appointed Senators. As such, Move Forward leader Pita Limjaroenrat failed to gain enough votes to become prime minister. The opportunity to form government passed to Pheu Thai who formed a coalition excluding Move Forward that included conservative parties such as Bhumjaithai, and the military-backed Palang Pracharath and United Thai Nation parties. Their candidate, Srettha Thavisin, was elected prime minister on 22 August with the support of most Senators. The 2026 election was the third election under the 2017 constitution, which was implemented under Prime Minister Prayut Chan-o-cha and the National Council for Peace and Order (NCPO) and the first after the expiration of the constitution's five-year transitory provision that gave the Senate voting rights to choose the prime minister in a joint session of parliament.
Laboratory studies indicate that BDNF may play a role in neurogenesis. BDNF can promote protective pathways and inhibit damaging pathways in the NSCs and NPCs that contribute to the brain's neurogenic response by enhancing cell survival. This becomes especially evident following suppression of TrkB activity. TrkB inhibition results in a 2–3 fold increase in cortical precursors displaying EGFP-positive condensed apoptotic nuclei and a 2–4 fold increase in cortical precursors that stained immunopositive for cleaved caspase-3. BDNF can also promote NSC and NPC proliferation through Akt activation and PTEN inactivation. Some studies suggest that BDNF may promote neuronal differentiation. Preliminary research has focused on the possible links between BDNF and depression.
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Dapagliflozin/metformin, sold under the brand name Xigduo Xr among others, is a fixed-dose combination anti-diabetic medication used as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes. It is a combination of dapagliflozin and metformin and is taken by mouth. Dapagliflozin/metformin was approved for use in the European Union in January 2014, in the United States in February 2014, and in Australia in July 2014.
[...] None of the participants to the conflict saw the events of 7–8 August in isolation, nor present them as isolated. How those events are interconnected is essential to determining the story." Fawn and Nalbandov paid attention to the report that during the military exercise "Kavkaz 2008" in the North Caucasus, which concluded in early August, a leaflet entitled "Soldier, know your probable enemy" (describing Georgia), was distributed among the Russian trainees. Fawn and Nalbandov argued: "The Russian military measures were part of a Russian strategy and possibly a genuine belief that Moscow was acting in accordance with, and upholding, international law and norms." Fawn and Nalbandov also argued, "Different events, and different interlinkages, create the story. What is common is that every event is used rhetorically as the ‘start’, which justifies retaliation." The researchers noted that "each military clash led to mutual blame by the belligerent parties: each side accused the other of opening the first salvo and characterized its actions only as a response." The researchers concluded, "The August war did not come out of nowhere. [...] The precise ignition of the war rests on specific timing in the late hours of 7 August and early hours of 8 August, and when and why Russian armor traveled through the Roki tunnel from the Russian Federation into Georgia." In August 2012, Scott C. Monje, senior editor of the Encyclopedia Americana, argued: "Thus, provocations and incidents had become commonplace over the course of several years, and they frequently occurred in the summer.
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It indicates the oxidized form, which has a positive charge on the nicotinamide nitrogen. The reduced partner NADH lacks that charge and carries added electrons. The plus sign is part of the standard abbreviation, not a separate ion.
No. It also serves as a substrate for signaling and DNA-repair enzymes such as sirtuins and PARPs. Those reactions consume NAD+ and connect its availability to cellular regulation. Energy transfer remains its most abundant known role.
NAD+ is the oxidized electron acceptor, while NADH is the reduced electron carrier. They form a reversible redox pair and differ by a hydride ion. Cells maintain different ratios of the two depending on conditions and compartment.
NAD+ and NADH can interconvert quickly after a sample is collected, which can alter the measured ratio. Rapid quenching and cold handling limit enzymatic and chemical changes.