Health Claims

If people with long-COVID take a supplement called nicotinamide riboside for 10 weeks, those who see bigger boosts in a molecule called NAD+ also tend to report better sleep — which might mean NAD+ plays a role in how we sleep.

Taking 2000 mg of nicotinamide riboside every day might be hard for people with long-COVID because more than half stopped taking it within 20 weeks, mostly because they felt worse or got sick again.

Taking 2000 mg of nicotinamide riboside every day for 10 weeks might help people with long-COVID feel a little better in terms of thinking clearly, feeling less tired, sleeping better, and feeling less down.

Taking a supplement called nicotinamide riboside every day for up to 20 weeks doesn't seem to help improve thinking skills in adults who are still dealing with long-term effects from COVID-19.

Taking 2000 mg of a supplement called nicotinamide riboside every day for 5 to 10 weeks can boost energy-related molecules in the blood by more than double in people still dealing with long-term effects of COVID.

Taking NMN supplements probably won't help improve blood sugar or cholesterol levels in most middle-aged or older people who are already fairly healthy.

Taking NMN by mouth boosts a molecule called NAD+ in your blood, but after 12 weeks, it doesn’t seem to help with blood sugar or cholesterol levels — at least in healthy adults.

Taking NMN for up to 3 months might slightly lower insulin resistance, but the effect is so small it probably doesn’t matter—and it goes away if you ignore certain studies.

Taking NMN pills every day for up to 12 weeks doesn’t seem to change weight, blood pressure, or liver health in middle-aged or older people.

Taking NMN supplements for up to 3 months doesn’t seem to help improve blood sugar or cholesterol levels in healthy older adults.

Your body can make an important molecule called NAD+ in more than one way — not just from one specific building block, but also from others like nicotinamide riboside.

In yeast, a substance called nicotinamide riboside can be used to make an important molecule called NAD+, and it does so through a different route than the one scientists used to think was the only way.

In mice, a vitamin-like substance called nicotinamide and its cousin NR get sent into bile after being injected, travel to the gut, get changed into another form by gut bacteria, and then help the liver make an important energy molecule—cutting off the bile stops this process.

In mice, when they take NMN or NR supplements by mouth, their muscles don’t turn these directly into NAD+—instead, the body first breaks them down into a form called nicotinamide and rebuilds them through a specific recycling process.

In mice, a specific biological pathway called Preiss-Handler is the main way the liver makes an important molecule called NAD+ after giving NMN or NR, because when scientists turned off a key part of that pathway, NAD+ didn’t go up anymore.

When mice get NMN or NR through an IV, their bodies quickly break it down, send it to the gut, where gut bacteria turn part of it into another form that gets recycled back to the liver to make an important energy molecule—so the gut-liver loop is key, even with injections.

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.

In mice, about a third of the energy molecules made by gut bacteria in the colon come from breaking down certain plant fibers from food.

In mice, the body absorbs vitamin B3 (nicotinic acid) early in the gut, so gut bacteria farther down don’t get much of it — scientists saw almost no labeled B3 ending up in those bacteria’s cells.

Your gut bacteria can turn a form of vitamin B3 from your body into another version that gets reused to make important energy molecules, especially when your body’s usual recycling system isn’t working well.

In mice, a nutrient made by the body called nicotinamide travels to the gut and becomes the main building block that gut microbes use to make an important molecule called NAD—most of it in the small intestine. This shows the microbes rely heavily on the host's nutrients to survive.

Taking NMN or NR supplements probably won't help older adults keep their muscle strength or size, even if they're healthy or take it for up to six months.

Taking 1000 mg of NMN every day for a month doesn’t help older adults with obesity get stronger in chest or leg presses, and might actually make their thigh muscles smaller compared to taking a fake pill.