When you take NR or NMN supplements, your gut bacteria turn them into a form of vitamin B3, which your body then uses to make an important molecule called NAD+ that helps keep your cells healthy.

When mice take NMN or NR supplements by mouth, most of it gets changed into another form—nicotinic acid—by gut bacteria before the body uses it. The liver mostly uses this changed form to make an important molecule called NAD+, and only a little bit gets used directly.

In mice, a supplement called nicotinamide riboside only boosts energy-related molecules if gut bacteria first turn it into a different form—without those bacteria, the supplement doesn’t work.

Taking NR or NMN supplements by mouth seems to boost a key molecule called NAD+ in your blood, which scientists think might be good for aging, but we don’t know yet if it actually makes a real difference to health.

After being given through an IV, NMN and NR end up in your gut through bile, where your gut bacteria turn them into a form of vitamin B3 that your body can use to make an important energy molecule called NAD+.

When you add a vitamin called nicotinamide riboside to gut bacteria in a lab, the bacteria turn it into another helpful compound, and this happens the same way in everyone — no matter their age or health condition.