02. What the studies found
NAD+ research found a blood rise, not a cure
You'll get the strongest result first. Next comes the type of person tested and the questions left open.
What the studies in people have shown
The firm result is narrow. NMN or NR pills left more NAD+ in blood.
Both come from a common vitamin. After swallowing either pill ingredient, you may make NAD+ from it.
The studies haven't proved that these pills prevent illness or slow aging. A blood test can't answer those questions for you.
Your body makes proteins, which are working parts inside cells. Some use NAD+ to mend DNA or help your immune system.
Most other findings come from mice or loose cells in lab dishes. Those tests can guide research, but your answer needs a study in people.
What NAD+ helps your cells do
With help from NAD+, a cell can draw energy from food [5]. That power keeps the cell working.
A cell also uses some NAD+ while mending damage [5]. Working proteins need it to repair DNA and help your immune system [5].
Scientists tested loose cells kept in a dish. A protein repaired all the DNA damage it could when NAD+ was present [12].
That wasn't a test in a person. It can't show whether taking more NAD+ repairs DNA inside you.
When DNA is badly damaged, the cell may keep trying to mend it. Those repair jobs can drain the cell's NAD+ [11].
The cell may then lose its energy and die. Scientists study this process in cancer, in swelling, and in damage that can happen when blood returns to part of the body after being cut off for a time.
What lowered NAD+ in older mice
The strongest clue came from mice. Their bodies make a protein that breaks down NAD+.
As the mice aged, that protein worked faster. Mice lacking the protein kept more NAD+, and their cells handled energy better [2].
That's a result in mice, not people. It doesn't prove the same process drives aging in you.
A review also looked at immune cells. They need NAD+ for power, to mend DNA, and to hold swelling down [13].
Another mouse study set off an immune response. During that response, immune cells damaged DNA and used up NAD+ [10].
These findings may explain part of the drop in mice. They haven't proved that taking more would help you.
What differs between NAD+, NMN, and NR
The label can fool you. Pill studies usually don't use NAD+ itself.
Your gut takes in only a small share of the finished NAD+ molecule. Pills may hold NMN, NR, or nicotinamide, another form of the same vitamin [14].
Inside your body, those smaller ingredients become NAD+. NR becomes NMN, and NMN then becomes NAD+ [5].
When you read a study, check what people swallowed. The blood result alone doesn't show that they swallowed NAD+ itself.
What the NR pill ingredient changed
NR is a pill ingredient made from a common vitamin. It has more safety research in people than similar ingredients.
The blood test changed most clearly. Better health wasn't shown.
Adults in one trial carried extra weight and had no other known health problem. The trial lasted eight weeks.
Blood NAD+ rose 22% with 100 mg/day, 51% with 300 mg/day, and 142% with 1000 mg/day. Bad cholesterol didn't rise, and side effects weren't worse than with a placebo, or sugar pill [4].
A second trial studied healthy adults who were middle-aged or older. They took 1000 mg/day for six weeks.
Blood NAD+ stayed about 60% higher. Researchers saw no grave side effects [6].
Large blood vessels looked less stiff, but the study couldn't show that the pill caused the change. Blood pressure also looked lower, yet that result could have happened by chance.
What the NMN pill ingredient changed
NMN is another pill ingredient made from a common vitamin. One trial gave healthy men one pill containing 100, 250, or 500 mg.
The men had no clear bad change. Heart rate, blood pressure, oxygen, sleep, and lab tests stayed much the same [7].
Another trial gave people 300-900 mg/day for 60 days. Compared with the placebo, or sugar-pill, group, all amounts brought a higher NAD+ blood reading [3].
People could walk farther and scored better on questions about daily tasks. They also said they felt better.
A separate score tried to estimate how fast their bodies were aging. It didn't worsen, which was the better result, but that result alone says nothing sure about your health.
The researchers favored 600 mg/day among the tested amounts. Safety checks found no problem at any tested amount.
FDA rules can bar supplement sales when drug testing on an ingredient began first. The FDA says that rule applies to NMN.
That doesn't mean NMN is banned. The sales dispute doesn't change what happened in these trials.
What NAD+ benefits remain unproved
Blood tests give the clearest result. Tests after NMN or NR pills found higher NAD+ in blood [4][6].
Researchers seldom take small pieces of muscle or an organ from people. That blood change alone isn't better health for you.
One study followed women at risk from high blood sugar. For 10 weeks, they took 250 mg/day of NMN [1].
Their muscles pulled sugar from blood more easily when insulin told them to do so. The women might not feel that change.
Their weight and months-long blood sugar reading both stayed steady. In another NMN trial, participants walked farther [3].
That walking result may not fit everyone. A 2025 review found little solid support for wide health gains [14].
Longer life and fewer illnesses still lack proof in people. That's the limit of the studies so far.
What your body does with an NAD pill
Study pills tend to hold NMN or NR because very little NAD+ itself passes your gut [14]. In your body, either ingredient may become NAD+.
Both ingredients raised blood NAD+ in fair trials with people [3][4]. A 2025 review found no solid proof that the rise improves health [14].
What changed after people took NAD pills
People took pill ingredients, and researchers measured NAD+ in blood and samples taken from the body [5]. One study found that muscles pulled sugar from blood more easily [1].
In a second study, participants covered more ground on a walk [3]. Both changes occurred in certain people, so they may not happen to you.
What NAD+ hasn't shown about looking younger
Trials in people haven't found that NAD+ makes anyone look younger. The idea mainly comes from rodents and lower NAD+ in samples from older bodies [5].
That doesn't prove a younger look for you. The review found that people still lack clear proof of broad gains [14].
What NAD studies found about weight loss
Studies in people haven't shown weight loss. In one NMN study, muscles pulled sugar from blood more easily [1].
Weight and the months-long blood sugar reading stayed steady. Some mice lost weight or gained less, but that can't prove you'll lose weight.
What NAD studies found about weight gain
Trials in people haven't reported a gain in weight. In one NMN study, neither weight nor the mix of fat and muscle changed [1].
Older mice gained weight more slowly during long-term NMN use. That doesn't tell you what NMN will do to your weight.
What NAD studies found about having children
Most work on having young used animals. Studies in people haven't found that NAD+ helps a man or woman have a child.
A 2025 review found scant proof that human health improved [14]. Animal work can't settle this question for you.
What NAD studies say about morning or night
No trial in people answers this question. The amount your body makes rises and falls over 24 hours [5].
No study has proved that one time of day beats the other. Your body's daily change doesn't settle the best time for you.