What is NAD+? Follow the electron handoff

What is NAD+ and what does it do in the body?

NAD+ stands for nicotinamide adenine dinucleotide. It's a coenzyme that carries electrons during energy metabolism and serves as a substrate for enzymes involved in processes such as DNA repair.

One molecule, two states

Follow an electron handoff. As enzymes break down nutrients, NAD+ accepts electrons and becomes NADH. NADH can later hand those electrons on. In mitochondria, electron transfer helps drive the machinery cells use to make ATP, which powers many kinds of cellular work. Once NADH gives up the electrons, it can return to the NAD+ form and take part in another handoff.

The plus sign marks the oxidized form in this pair. The H marks the reduced form. If you see both on a chart, think of two states of a carrier moving through a series of reactions. See the review of NAD+ metabolism. You can also compare NAD+, NADH, NMN and NR.

NAD+ has another job

Some enzymes consume NAD+ as a substrate. For example, enzymes in the PARP family use it to create chemical signals involved in responding to DNA damage. The electron handoff and the repair signal are two different uses of the same molecule. Cells also have pathways that make and replenish NAD+.

Why the word “energy” gets confusing

In a cell biology paper, energy might mean ATP production or another step in metabolism. In everyday conversation, it might mean whether you feel more alert after lunch. A supplement or spray claim about how you feel needs human research that measures how people feel or perform. Cellular chemistry explains why the question is worth asking in the first place. See how researchers could test energy and focus.