Pills, IV drips, and shots
What NAD+ studies found in blood, muscle, and walking
Walking farther is easy to picture. Start with changes people could notice, then read the blood findings. You'll also see why shots and drips remain unproved.
What NAD+ may change, and what remains unclear
Walking farther or rising from a chair is easy to picture. Some pill studies found gains in those tasks, along with higher NAD+ blood levels. NAD+ is a small substance that each cell makes and uses for power, and it isn't a drug or a single product on a shelf.
On many bottle labels, NAD+ means NMN or NR. Those short names stand for two materials related to niacin; after they enter the body, each can become NAD+. Studies checked the pills with blood tests and simple tasks such as walking. You can read those findings here; they are not a dose chosen for you.
How NAD+ helps a cell draw power from food
Your cells break food down in a chain of small steps. NAD+ carries electrons between those steps, which helps a cell release usable power [5]. Electrons are tiny parts of atoms that carry an electric charge. The cell prepares the same NAD+ to carry them again.
Some proteins use NAD+ while mending DNA or calming harmful swelling inside tissue [5]. Food gives the body material to replace what those proteins use. The balance changes during each day. One blood test can't show what is happening in every organ.
A 2021 review found that NAD+ often declines with age in humans, mice, worms, and yeast [5]. In one mouse test, scientists removed a protein that uses much NAD+. Those mice lost less NAD+ as they aged than other mice [2]. A result in mice can't tell us whether a person would feel better.
What NAD+ pills changed in people
The strongest work in people tested pills made from NMN or NR. Among adults carrying extra weight who were otherwise healthy, NR raised the NAD+ blood level. The gains were 22%, 51%, and 142% after 100, 300, and 1000 mg/day for eight weeks [4]. Side effects were equally common with placebo, the pill that contained no NR.
Another study tested NMN at 300, 600, and 900 mg/day for 60 days. Blood NAD+ rose in every group on days 30 and 60 [3]. People also walked farther, and 600 mg/day had the best combined rating for blood, walking, body-age, and safety. No safety problem appeared at any amount in that study.
Changes a person might feel are less certain: after ten weeks at 250 mg/day, insulin helped the women's muscles take in more sugar [1]. Neither body weight nor the past-months sugar test changed. A 2024 review of ten studies and 437 people found better walking and chair rises [15]. A 2025 review still found too little proof of clear gains in health or daily life [14].
How niacin gives the body material for NAD+
Niacin supplies vitamin material for making NAD+. Niacinamide, also called nicotinamide, is a vitamin closely related to niacin. NR and NMN are two other starting materials for NAD+. None is finished NAD+ when swallowed.
The body changes NR twice before it becomes NAD+, while NMN needs one change. Very little whole NAD+ gets through the gut because its size and charge hold it back [8]. NR and NMN enter more easily. Research on either starting material isn't research on swallowed NAD+.
What NAD+ helps cells keep doing
NAD+ helps cells release power from food [5]. Cells also draw on the NAD+ supply to repair DNA and help hold swelling down. One small substance takes part in each of these separate jobs.
What an NAD+ supplement has and hasn't shown
Most NAD+ supplement studies gave people pills made from NMN or NR, and either form raised the NAD+ blood level [4][1]. These pills aren't approved drugs, and gains in strength or health have varied. One broad review found too little sound proof of clear health gains [14].
What a higher NAD+ blood number cannot prove
In several sound studies, both kinds of pills raised blood NAD+ [4][3]. A raised blood reading cannot tell you whether you will feel better. The number also cannot show what changed inside each organ, and studies have a much harder time answering that question.
Some studies found better insulin use in muscle or farther walking [1][15]. Those findings give researchers a reason to keep looking, and they don't settle whether health improves for years. A 2025 review found too little proof of lasting help in health or daily life [14].
What NAD+ is, and how it differs from a peptide
Scientists use NAD+ for the form that is ready to pick up electrons [5]. An electron is a tiny part of an atom with an electric charge. After giving the electrons away, NAD+ changes form and a cell can prepare it again.
A peptide links amino acids in a chain; these are the basic materials in proteins [5]. NAD+ is put together another way, with two joined sections that carry electrons. Every living cell makes NAD+ for its own use. The name does not describe a drug or a disease.
Where each NAD+ question is answered
No clinic or shop runs this guide. Start with NAD+ and metabolism for findings about blood, muscle, and walking. Read IV NAD+ therapy for drips, shots, and their risks. Each page says whether a study tested people, mice, or cells kept in a dish.
The dose page lists only amounts used in studies, and those amounts aren't personal advice. Each claim number leads to the full paper in the study references. The guide favors no brand and sells nothing.