NAD⁺ (nicotinamide adenine dinucleotide) !

NAD⁺ picks up electrons in glycolysis and the Krebs cycle and carries them to the mitochondria as NADH. It is made from niacin.

Updated 2026-10-31

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Key facts

It accepts a hydride ion (H⁻) on its nicotinamide ring and becomes NADH.
It is made from niacin (vitamin B3) or from tryptophan (about 60 mg of tryptophan per 1 mg of niacin).
Cytosolic NADH enters the mitochondria through shuttles: malate–aspartate or glycerol-3-phosphate.
NADH absorbs light at 340 nm and NAD⁺ does not: the basis of many lab enzyme assays.

Two nucleotides joined through their phosphates: one with nicotinamide (the working part), one with adenine.

Niacin lack causes pellagra: dermatitis, diarrhea, dementia and, untreated, death.
Hartnup disease and carcinoid syndrome can cause pellagra because they steal tryptophan.

Think of the answer, then tap the question to see it.

Which vitamin is NAD⁺ made from?

Niacin (vitamin B3); it can also be made from tryptophan.

What are the three Ds of pellagra?

Dermatitis, diarrhea and dementia (the fourth is death).

Which glycolysis step reduces NAD⁺ to NADH?

Step 6, glyceraldehyde-3-phosphate dehydrogenase.

Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.

Educational information, not medical advice. For any symptom, see a health professional.

Sources: Nicotinamide adenine dinucleotide (CID 5892) (PubChem, NCBI, 2026) · Public domain; Pellagra: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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