The helper that gets scarcer with age

In every cell there is a helper substance that hardly anything can do without. Over the years it gets scarcer, and not because the body makes less of it.

What NAD is needed for

NAD is not a nutrient in the usual sense. It is a helper that hundreds of processes depend on. It is involved when food is turned into energy, and it is needed when damage to the genetic material is repaired. Without it, both run more slowly.

What the measurements show

Studies on human tissue show a clear decline over the course of life. A study published in 2012 followed this across several age groups.

Not less is made, more is used up

You would expect the body to make less of it with age. In fact, it keeps making it; more of it is simply broken down. An enzyme called CD38 becomes more active over the years and breaks down NAD. In 2016, it was described as a main driver of this decline.

The way back

The body hardly covers its needs by building new NAD. Instead, it recycles: used nicotinamide is collected and fed back into the cycle. Most of the supply runs through this route.

This route has a competitor, though. Another enzyme attaches a small chemical tag to the nicotinamide and in this way removes it from the cycle. The body also needs such tags, which experts call methyl groups, for many other tasks.

So two things are linked that at first glance have nothing to do with each other: the cell's energy supply and the body's supply of these tags. Betaine, also called trimethylglycine, is one of their most important sources in the diet.