NAD+: The Tiny Helper First Found in Yeast Juice

In 1906, two scientists were studying yeast juice. Yeast are tiny living cells that turn sugar into alcohol and bubbles. The team pushed the juice through a very fine filter and split it in two.

Alone, neither part could turn sugar into alcohol. Mixed back together, the bubbles came back. A tiny helper had slipped through the filter. Today we call it NAD+, and every cell in your body uses it.

What it is

NAD+ is not a peptide. A peptide is a short chain of amino acids, like a short bead bracelet. New to this? Start with what a peptide is.

NAD+ is a coenzyme instead. That is a small helper that enzymes need to do their jobs. Enzymes are the cell's tiny workers, and hundreds of them use NAD+.

Your cells build NAD+ from forms of vitamin B3 in food. They can also make it from tryptophan, an amino acid found in protein. Two of its building blocks have short, well-known names: NR and NMN.

In 1929, studies of how yeast juice breaks down sugar, including this helper, earned a Nobel Prize in Chemistry. NAD+ belongs on a peptide site because it sits at the heart of cell energy and aging research.

What it does in the body

Your cells get energy by slowly breaking down food. NAD+ helps carry that energy to where it is needed.

Think of NAD+ as a honeybee. As food breaks down, it picks up a load of electrons. These are tiny charged specks that hold energy. Once loaded, it gets a new name: NADH.

It flies the load to the mitochondria, the cell's power plants. There it drops off the electrons, which help make the cell's fuel. Then it heads back, empty, for more.

NAD+ has a second job, too. Some proteins use it up as they work. One group helps fix damaged DNA. Another group, called sirtuins, helps keep some genes switched off. Sirtuins need NAD+ to work.

What scientists have found

In cells: Yeast gave scientists another big clue. In 2000, a team put yeast cells on a low-calorie diet. The cells lived much longer.

But the bonus vanished in yeast missing a key sirtuin gene. It also vanished in yeast missing a gene they use to make NAD+. So the longer life seemed to need both.

In animals: In lab worms, flies and rodents, NAD+ levels drop with age. The drop ranges from about 10% to 65%, depending on the organ and the age.

In a 2016 study, mice got NMN, a building block of NAD+, for a full year. They gained less weight with age, even though they ate a bit more. Their bodies handled insulin better, and their eyes and bones held up better. The team saw no obvious harmful effects.

In people: Lower NAD+ also tends to go along with older age in people.

In small trials, healthy volunteers took NR or NMN. Their NAD+ levels rose, and the building blocks appeared safe. Effects on other health measures have been mixed so far.

What about NAD+ itself? In a 2019 pilot study, eight healthy men got NAD+ by a slow drip into a vein. Three more got a salt-water drip instead. For the first two hours, blood NAD+ did not change, as the body cleared it fast. By the end of six hours, it had climbed well above where it started. No side effects were seen during the drip.